sign in sign up
<<
Home , Human nutrition, Nutrition

Trends in & 14 (2003) 191–209

2. Genetically modified food classical deficiencies, although over-consump- crops and their tion is a problem for some. Also in relatively wealthy countries there is, in general, good access to affordable medical care to meet needs and most consumers contribution to in rich countries have access to a relatively inexpensive supply of safe and healthy food. In these settings, the possibility that might reduce the price of food or make food more beneficial to health is a rela- tively minor concern. Rather, public debate about and genetically modified (GMFs) appears to have focused on the potential for harm to either the environ- ment or health without a clear definition of benefit to the consumer. a The situation, of course, is quite different in poor Howarth E. Bouis *, Bruce countries where and ill health are frequent. M. Chassyb and James Poor consumers typically spend 70% of their incomes c on food, and diets consist primarily of staple foods, O. Ochanda which lack the , and, very likely, other food components necessary to sustain good health and minimise the risk of adult onset -related chronic . In addition, low incomes typically preclude the poor from access to adequate health care. aInternational Research Institute, 2033 K There are three broad ways that biotechnology may Street, NW, Washington DC 20006 USA (fax: +1-202- benefit consumers in developing countries. First, bio- 467-4439; e-mail: [email protected]) technology offers a powerful, new tool to improve crop bBiotechnology Center, University of Illinois at productivity, both by making conventional breeding Urbana-Champaign, 238 NSRC, 1101 West Peabody faster and more efficient and, more controversially, by Drive, Urbana, IL 61801, USA the insertion of novel genes in a crop species, by use of cDeparment of , College of Biological & transgenic methods. This includes the ability to bring Physical , University of Nairobi, PO Box new lands with unfavourable growing environments, 30197 Nairobi, Kenya such as those with high saline , under production. Second, pesticide applications may be reduced through adoption of Bt-containing crops (i.e. crops with resistance owing to the introduction of the Bacillus 2.1. Introduction thuringiensis (Bt) gene encoding an insect-specific This chapter discusses the potential of biotechnology toxin). Reducing pesticide use can improve the health of to improve the health and nutrition of consumers in farmers, in addition to lowering input costs. Third, developing countries. In the relatively wealthy countries transgenic methods may be used to improve the micro- of Europe, North America and elsewhere, consumers nutrient content and/or of commonly spend perhaps 10% of their income on food. For the eaten foods in developing countries. most part consumers in developed countries are free of The first pathway, that is improving crop productiv- ity, is associated with an often-asked question—Does feeding the world depend on the use of biotechnol- * Corresponding author. ogy?—The answer largely depends on perceptions of the

0924-2244/03/$ - see front matter # 2003 Published by Elsevier Ltd. doi:10.1016/S0924-2244(03)00073-6 192 H.E. Bouis et al. / Trends in & Technology 14 (2003) 191–209 current situation. Countries around the world are declining; in some cases they have been increasing over already using most of the arable land available for the past 30 years. . As continue to grow, increasing Because of poor dietary quality and consequent the supply of food to meet future world food needs will malnutrition, some people, especially depend on increasing yields. This, in turn, requires children and their mothers who have higher require- investments in agricultural research to increase the yield ments for vitamins and minerals, have higher mortality, potentials of specific food crops as well as fish and live- become sick more often, have their cognitive abilities stock production. compromised for a lifetime, and are less productive Conventional breeding of has been especially members of the workforce than might otherwise have successful over the past three decades. Through research been the case. Their quality of and aggregate eco- and extension efforts associated with the ‘Green Revo- nomic growth are unnecessarily compromised. To make lution’, the rate of increase of production of , , matters worse, the adverse synergy between under- and in developing countries has outpaced popu- nutrition and infection results in nutrition requirements lation growth and other factors associated with above those that characterise the needs of well-nour- increased demand (for example higher ished populations. incomes), such that the inflation-adjusted prices of rice In developing countries demand for non-staple foods and wheat fell by 30–40% between 1970 and 1997 is growing faster than demand for cereals, as ever-richer (World Bank, 1990–1999).1 purchase more non-staple foods than cer- World supplies and prices of cereals are inter-con- eals, with consequent pressure on non- prices nected through international trade. Advances in con- to increase. In addition, increasing the productivity of ventional breeding in Australia, Europe, and North non-staple foods through agricultural research (and so America have also contributed to falling prices. lowering prices) is much more expensive than increasing Continued low prices of cereals are likely as long as the productivity of staple foods, because of the far lar- investments in agricultural research continue, although ger number of non-staple foods involved. a worrisome trend is that funds for public research in From this perspective, then, the world is already fail- agriculture have been declining (Rosegrant, Paisner, ing to provide an adequate supply of non-staple foods Meijer, & Witcover, 2001). for a large proportion of its , and prospects It is often said that there is enough food in the world are somewhat bleak for short- to medium-term to feed everyone. Except for some pockets of extreme improvements. Biotechnology affords a powerful new poverty and dislocations owing to natural disasters and tool to help increase the supply of food produced in the civil strife, this is largely the case for cereals. Cereals world and redress, in part, situations characterised by (and and tubers) provide the cheapest sources poor dietary quality. of to meet requirements for poor populations. Chapter 3 discusses ways, including reduced use of The availability of affordable staple foods prevents pesticides (i.e. the second pathway, above), in which explicit , as defined narrowly in terms of energy biotechnology can provide breakthroughs in improving requirements. the productivity of crops. However, it is well beyond the However, a range of non-staple foods, such as scope of this special issue to speculate on the rate of and fish products, , pulses, and , are growth of world food supplies with and without the use foods rich in bioavailable vitamins and minerals or of biotechnology. and possibly other food components, A third pathway through which biotechnology can which are necessary for good health and a productive improve the nutrition and health of consumers in life. As discussed in more detail below, micronutrient developing countries is through increasing the undernutrition is widespread in poor countries, affecting and content and bioavailability of staples and more than one-half of the population in the developing other foods and/or reducing allergens, an approach world. This situation is due primarily to diets of low which is focused on in this chapter. It must be empha- nutritional quality. The poor want to eat larger sised that none of the products discussed in this chapter amounts of non-staple foods, and most often these has been introduced commercially, though they are in foods are available in local markets. However, such various stages of research and development. Thus, non-staple foods are simply too expensive to be eaten by importantly, both the efficacy and effectiveness of this the poor in large quantities owing to a combination of pathway requires documentation. high prices and low purchasing power. The inflation- Although it is obviously important to provide an adjusted prices of non-staple foods have not been account of the range of specific efforts being developed to improve the nutritional content and health-enhancing properties of particular foods, it is also necessary to 1 World Bank: Commodity Markets and the Developing Countries; place these activities in the context of alternative inter- Global Commodity Markets. ventions (i.e. interventions that do not involve the use of H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 193 biotechnology) that might solve these malnutrition and It is only relatively recently that working health problems in other ways. This is accomplished by in developing countries have demonstrated conclusively (i) examining the relative costs of nutrient supple- that, during times of relative economic and political mentation and commercial nutrient fortification pro- stability, many children and adults, particularly women grams that are already being implemented to reduce in their child-bearing years, suffer more from a lack of micronutrient malnutrition and (ii) examining the recent essential vitamins and minerals in their diets than from history of attempts to improve the micronutrient con- a lack of . People, for the most part, are not tent of staple food crops—efforts that have involved aware that their diets lack such trace and so do use both of biotechnology and conventional plant not associate these deficiencies with listlessness, poor breeding. Recent developments in efforts to breed - eyesight, impaired cognitive development and physical and beta-carotene-dense are described in this growth, more frequent and severe bouts of illness, and chapter as a concrete example, illustrating several key high mortality. For this reason, the general problem of generic issues associated with the use of biotechnology poor dietary quality has been dubbed ‘hidden hunger’. to breed for characteristics that have direct benefits for It is useful to summarise very briefly the scale and consumers. consequences of micronutrient malnutrition in develop- It is important to keep in mind that the final, sus- ing countries. It is estimated that over 3 billion people in tainable solution to micronutrient malnutrition in developing countries are iron-deficient (Administrative developing countries is a substantial improvement in Committee on Co-ordination, Subcommittee on Nutri- dietary quality by higher consumption of pulses, fruits, tion, & International Food Policy Research Institute, vegetables, fish, and animal products, which the poor 2000). The problem for women and children is more need and already desire, but cannot presently afford. severe because of their greater physiological need for Realisation of this goal of high quality diets will require iron. In poor countries, more than half of pregnant (i) substantial investments by farmers, private busi- women and more than 40% of non-pregnant women nesses and public agencies to build the infrastructure to and preschool children are anaemic. Iron deficiencies produce and bring to market the requisite supply of during childhood impair physical growth, mental devel- non-staple foods, (ii) sound government policies to sti- opment and learning capacity. In adults, iron deficiency mulate agricultural and economic growth, (iii) con- reduces the capacity to do physical labour. Severe iron siderable increases in the incomes of the poor during the deficiency is a leading contributor to death among course of economic development over many decades, or women during childbirth, owing to low haemoglobin (iv) other strategies (e.g. subsidies) designed to enhance levels in the light of physiological blood loss. the accessibility of these products to wider populations. Globally, about 3 million children of preschool age Meanwhile breeding staple foods that are dense in have visible eye damage owing to a defi- minerals and vitamins can provide a low-cost, sustain- ciency. Annually, an estimated 250 000–500 000 pre- able, although as yet unproven strategy for reducing school children go blind from this deficiency and about existing levels of specific micronutrient undernutrition. two-thirds of these children die within months of going Sections 2.2–2.5 (below) discuss, in some detail, iron- blind. Estimates of the subclinical prevalence of vitamin and beta-carotene-dense rice, as an example of the A deficiency range from 100 to 250 million. A number development of a GMFcrop of potential importance in of clinical trials in developing countries have shown that developing countries. Section 2.6 describes the potential vitamin A supplementation, as capsules distributed of transgene to enhance nutritional and biannually in high doses, as weekly distributed low quality factors of food crops in general; this is impor- doses (consistent with levels attainable through food) or tant in both developing and developed countries, as a fortified product in diets can reduce mortality rates though perhaps has more immediate relevance in the among preschool children on average by 23% (Beaton latter. et al., 1993). Deficiencies in several other micronutrients, in parti- cular , may also be widespread, with equally serious 2.2. Potential contribution of GM technology: a consequences for health. However, because for some of case study on breeding of iron- and beta-carotene- these micronutrients, specific indicators are lacking to dense rices to help alleviate malnutrition screen for deficiencies, they have not received as much attention as iron, vitamin A and deficiencies. The World Bank (1994) estimates that at the levels of 2.2.1. Background to the problem of micronutrient micronutrient malnutrition existing in , 5% malnutrition in poor countries, its economic costs of gross national product is lost each year due to defi- and costs of present interventions to address the ciencies in the intakes of just three nutrients, namely problem iron, vitamin A and iodine. For each 50 million in 194 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 population, this translates into an economic loss of US nutritious varieties can be developed and their adop- $1 billion per year. tion by farmers can be initiated, such a strategy is sus- Some general cost calculations can be made for inter- tainable once breeding has been completed, and seeds ventions to relieve iron and vitamin A deficiencies by have been disseminated and adopted by farmers. Bio- supplementation and fortification in South Asia, which fortification has the potential to provide coverage for has a total population of roughly 1.25 billion people. remote rural populations, which supplementation and The costs of vitamin A pills themselves are low: an fortification programs may not reach, and it inherently often-quoted cost of vitamin A supplementation, which targets the poor who consume high levels of staple includes the costs of delivery, is US $0.50 per person per foods and little else. year (i.e. US $0.25 per capsule; World Bank, 1994). If However, efficacy and effectiveness trials and other one in every 12.5 people in South Asia were to receive studies have yet to be undertaken to determine both the supplements (i.e. 100 million people in total), this would degree to which nutritionally dense varieties can cost US $50 million per year, or US $500 million over improve micronutrient status and whether there are 10 years. An often-quoted cost of iron fortification is unintended negative effects. For example, untargeted US $0.12 per person per year (World Bank, 1994). If a approaches designed to increase bioavailable dietary particular food vehicle fortified with iron were to iron substantially must be considered with care. The reach 33% of the total (but untargeted) population in documented risks of iron deficiency must be weighed South Asia (i.e. 412 million people), the total cost against the potential for genetically determined would, again, be US $50 million annually, or US increased risks of toxicity from iron overload, given the $500 million over 10 years. In absolute terms, these relatively common occurrence of heterozygosity for nutrient-specific interventions may seem to be large haemachromatosis. Thus ‘permanent’ changes in the amounts of money, but they are very worthwhile food supply, which result in long term ‘high’ intakes of investments and actually represent quite small percen- iron should be considered in the light of the incomple- tages of the total economic activity of the South Asian tely described consequences of relevant polymorphisms economies. in genes that appear to play roles in the regulation of The Micronutrient Initiative (MI)2 estimates that 1 iron . Such risks have been studied most billion vitamin A pills have been distributed worldwide adequately in developed countries (Merryweather- since the inception of vitamin A distribution pro- Clarke, Pointon, Sherman, & Robson, 1997). grammes up to the end of 2000 and that 500 million However, according to an expert group convened to supplements are now given out annually. consider micronutrient supplementation and fortifica- A conservative estimate of the annual, recurrent cost tion with iron, iron overload disorders and haemochro- of global vitamin A supplementation programmes is, matosis are rare, even in those populations of European therefore, US $125 million. Assuming that 75% of the origin most susceptible to them; therefore, the use of world’s need for vitamin A is met, recurrent annual fortification and supplementation as estimated costs to meet all worldwide needs would be interventions for preventing and controlling iron defi- about US $165 million, or $1.65 billion over a 10-year ciency should not be constrained (UNICEF/UNU/ period. WHO/MI, 1999). It is safe to assume that the same Although benefit–cost ratios are quite high, supple- conclusions would apply to biofortification. If bioforti- mentation and fortification programmes must be sus- fication eventually were to replace supplementation in tained at more or less the same level of funding year some areas, there is the possibility that biofortification after year in any given country. If investments are not might lessen risks of overdosing, such as that recently sustained, benefits of course disappear. reported in , where toxicity associated with a mass Investments in research and dis- distribution of a vitamin A concentrate to children was semination are far lower (see Section 2.3.2) and thought, possibly, to have been the result of a changed potentially long lasting. Benefits of agricultural delivery routine (Sharma, 2001). research at a central location can be leveraged throughout the world and across time. Breeding for staple plants with high bioavailable micronutrient 2.2.2. Improving the nutrient content and content in their seeds, hereinafter referred to as ‘bio- bioavailability of minerals and vitamins in staple food fortification’, treats the underlying cause of micro- crops through biofortification nutrient undernutrition. Although plant breeding can involve relatively long lead times of 8–10 years before Breeding strategies

2 A Decade of Progress, a Lifetime of Hope: The Micronutrient There are three breeding sub-strategies that may be Initiative, 1990–2000, available [July 2003] at http://www.micronu- applied individually or in various combinations. These trient.org/frame_HTML/decade.pdf. are (i) reducing the level of antinutrients in food staples, H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 195 which inhibit the bioavailability of minerals and vita- A related strategy is to increase the level of phytase. mins, (ii) increasing the levels of nutrients and com- Phytase can break down phytates, thus increasing bioa- pounds that promote the bioavailability of minerals and vailability of minerals. Phytases have been used suc- vitamins, and (iii) increasing the mineral and vitamin cessfully in animal feeds (Nelson, Shieh, Wodzinski, & content. Experience with increasing the mineral and Ware, 1971; Rimbach & Pallauf, 1993; Yi, Kornegay, & vitamin content of rice is discussed in some detail in Veit, 1996). Phytase is present in the endosperm of rice, Section 2.2.3. for example, but is destroyed when rice is boiled for . Heat-stable phytase may be introduced in food Reducing antinutrients staples through genetic transformation (Holm, Kris- tiansen, & Pedersen, 2002). A breeding strategy of lowering the level of anti- nutrients, such as phytic acid, which binds in , has often been suggested as a way to increase the Increasing levels of compounds that improve bioavailability of minerals already consumed. absorption and utilisation of nutrients Phytin is the primary storage form of in most mature seeds and and is an important Certain amino acids, such as , enhance iron compound required for early seed germination and and/or zinc bioavailability (Hallberg, 1981). These seedling growth (Welch, 1986; Wise, 1995). Phytin plays amino acids occur in many staple foods but their con- an important role in determining mineral reserves of centrations are lower than those found in meat pro- seeds and thus contributes to the viability and vigour of ducts. A modest increase in the concentrations of the seedling produced (Welch, 1993). these amino acids in plant foods may have positive Graham and Welch (1996) argue that selecting for effects on iron and/or zinc bioavailability in . seed and grain crops with substantially lower phytin Iron and zinc occur only in micromolar amounts in content could have an unacceptable effect on produc- plant foods, so only micromolar increases in the tion, especially in regions of the world where there are amounts of these amino acids may be required to soils of low phosphorus status and/or poor micro- compensate for the negative effects of antinutrients on nutrient . Such attempts to lower the anti- iron and zinc bioavailability. These amino acids are nor- nutrient content of seeds and grains significantly require mal constituents of plants, so relatively small increases in a major shift in seed or grain composition. Because their concentrations in plant tissues should not have most of the antinutrients known to occur in seeds and adverse consequences on plant growth (Graham & grains are major organic constituents of these organs, Welch, 1996). they may play beneficial roles in plant growth and may However, when manipulating content, have other unidentified roles in human health. There- the net effects on the resultant product’s fore, Graham and Welch argue against a breeding quality should also be considered. The three most strategy that attempts to increase iron bioavailability by common measures of are protein effi- reducing antinutrient content. Antinutrients may also ciency ratios, biological value and net protein utilisa- reduce absorption of potentially toxic trace minerals tion. These measures are expressed as quotients of such as cadmium and other heavy metals (McLaughlin, retained (a constituent of protein) divided by Parker, & Clarke, 1999). the total intake of protein nitrogen. Among the However, Raboy (1996) has developed low phytic determinants of protein quality are amino acid pattern, acid (or lpa) mutant varieties of maize, rice, and barley. absolute levels of protein intake and physiological The phytic acid content of lpa seeds is reduced by 50– requirements for essential amino acids. Essential amino 80% compared with non-mutant seeds. The total acids are those that must be provided pre-formed amount of phosphorus remains the same—phytic acid is because of an inability for their de novo synthesis. replaced by inorganic phosphorus, which does not bind The higher the quality of a specific protein, the a range of trace minerals.3 These typically more efficiently it is utilised and the less is needed have little observable effect on other seed or plant to meet protein requirements. Thus changes in pro- characteristics. These mutants are presently being tested tein content or amino acid pattern of the resultant for agronomic performance and effects on micro- protein mix can have significant effects on the effi- nutrient status in humans. ciency of protein utilisation to meet nutritional requirements. An additional possibility is that as intakes of beta- carotene (converted to vitamin A after ) are 3 When such mutants are used as animal feeds, this also avoids increased, the utilisation of absorbed iron may be pro- what has become a serious problem— of unu- moted and vice-versa. That is, there are possible syner- tilised phytic acid. gies between increasing intakes of these two nutrients 196 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209

(Garcia-Casal et al., 1998). There is already consider- ably be necessary to encourage consumers to switch to able evidence for synergism between vitamin A and zinc more nutritious varieties. However, if these nutrition intakes (Smith, 1996). programs are successful, the yellow-orange colour will mark the more nutritious varieties from the Feasibility less nutritious, and a disadvantage will have been turned into an advantage (Hagenimana & Low, 2000). Will famers adopt nutrient-rich varieties?. Impact on is a particular concern of agriculturalists, 2.2.3. Increasing micronutrient content in rice whose first priority may be to raise the yield potential of plants rather than to address pro- Conventional breeding In a survey of traditional and modern varieties of rice, blems. If yield and profitability are compromised by Graham, Senadhira, Beebe, Iglesias, and Ortiz-Mon- breeding for nutrient content, farmers will not want to asterio (1999) reported that iron density in unmilled rice adopt nutritionally enhanced cultivars. However, rela- varied from 7 to 24 mg/kg (ppm) and zinc density from tively recent research has shown that mineral-dense 16 to 58 mg/kg. Nearly all the widely grown green seeds assist plants in resisting and other envir- revolution varieties were similar, at about 12 and 22 mg/ onmental stresses (Graham, Welch, & Bouis, 2001; kg for iron and zinc, respectively. The best lines dis- Welch & Graham 1999). More seedlings survive and covered in the survey of the existing germplasm collec- initial growth is more rapid. Ultimately, yields are tion were, therefore, twice as high in iron and 1.5 times higher, particularly in trace mineral ‘deficient’ soils in as high in zinc as the most widely grown varieties. These arid regions.4 ratios, therefore, are benchmarks for iron and zinc den- sity, which seem to be reasonably attainable using con- Will breeding for micronutrient-dense seeds change the ventional breeding. processing or consumer characteristics of staple foods?. High iron and to a lesser extent high zinc concentra- Mineral micronutrients comprise a tiny fraction of the tions were subsequently shown to be linked to the trait physical mass of a seed; for example, 5–10 mg/kg (ppm) of aromaticity. Most aromatic rices, such as jasmine in milled rice, and as much as 100 mg/kg in micro- and basmati types, are high in both iron and zinc, and nutrient-dense bean seeds. It is not known whether such generally in most minerals (Graham, Senadhira, & small amounts will alter the appearance, taste, texture, Ortiz-Monasterio, 1997; Graham et al., 1999; Senadhira or quality of foods. The dissemination strategy & Graham, 1999). A promising aromatic variety, desig- for trace minerals, then, would be to include the nated IR68-144, already being tested at the Interna- mineral-density trait in as many varietal releases as tional Rice Research Institute (IRRI) owing to its possible, in order to benefit a high proportion of the superior agronomic and consumer characteristics, was found to be high in iron (Gregorio, 2002). population, without having to rely on behavioural Expression of micronutrient-density traits has been change as a condition for success. This would be much tested over a wide range of environments and, although the same approach as adding fluoride to drinking the environmental effect itself is strong, the genotype in developed countries. As with the example of fluoride, effect is consistent across environments (implying that information on increased nutrient content would be the genotype-environment interaction is not serious), a made publicly available. finding that is sufficient to encourage a breeding effort. However, increasing levels of beta-carotene will turn Environmental factors considered by one or more crop varieties from white or light colours of yellow to dark programs include acid soils, alkaline soils, saline soils, yellow and orange. Often white varieties are much pre- acid-sulphate soils, iron-deficient soils, time of planting, ferred by consumers (e.g. milled rice, wheat flour, maize, field site, season, nitrogen fertilisation, phosphorus fer- cassava). Major programs will prob- tilisation, status, elevation and drought stress (Graham et al., 2001). 4 Biofortification will not deplete soils of trace minerals. Sufficient trace minerals are present in most soils for thousands of crops. Transgenic methods Some soils are labelled ‘trace mineral-deficient’ because the prop- erties of these soils are such that the trace minerals are chemically bound and so unavailable to the plant. Roots of trace mineral Increasing iron. Ferritin is an iron-storage protein efficient lines release compounds into the , which chemically found in , plants, and bacteria. The ferritin gene unbind the trace minerals in the soils and make them available to has been isolated and sequenced in plants, including the plant. Thus, a strategy of breeding for trace mineral efficient soybean, French bean, pea, and maize. Recent studies lines makes use of an untapped and abundant in the soil. This is a very different situation from depletion of macronutrients show that ferritin is used by both plants and animals as in the soil, such as nitrogen and phosphorus (Graham & Welch, the storage form of iron (Theil, Burton, & Beard, 1997); 1996). H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 197 orally administered ferritin, in non-transgenic foods Introducing a gene which codes for heat-stable phytase. (Beard, Burton, & Theil, 1996), and in transgenically- The level of phytase, which breaks down phytic acid, is derived ferritin-rich rice (Murray-Kolb et al.,2002) normally low in milled rice. Several studies have already can provide a source of iron for treatment of anaemia in demonstrated the usefulness of adding phytase to the rats. rice diets of poultry (e.g. Adrizal & Sell, 1996; Farrell & Martin, 1998; Martin, Nolan, Nitsan, & Farrell, 1998; Human studies with extrinsically radiolabelled animal Munaro, Lopez, Lopez, & Rutz, 1996; Teichman, Lopez, ferritin have indicated that, when added to a , iron &Lopez,1998). The phytase that does exist in rice seeds from ferritin is only about half as well absorbed as iron will hydrolyse the phytic acid present at lower pH levels, if from vegetables (Martinez-Torres, Renzi, & Layrisse, seeds are left to soak until germination in water. However, 1976; Taylor, Martinez-Torres, Romano, & Layrisse, boiling destroys the phytases that occur naturally in rice. 1986) and iron as ferrous sulphate (Skikne, Fonzo, Lynch, & Cook, 1997). However, a recent study has In one study, an amino acid was changed in the pro- shown that intrinsically radiolabelled iron in soybeans is tein sequence to make the phytase heat stable (Pasa- highly bioavailable (27%) to iron-deficient women montes, Haiker, Wyss, Tessier, & Van Loon, 1997). The (Murray-Kolb, Welch, Theil, & Beard, 2003). About phytase was active under the pH conditions of 50% of the iron in the soybeans was ferritin; the and degraded phytic acid in a very short time, during remaining iron, ferric phytate, is not thought to be model in vitro digestion. highly bioavailable. Lucca, Hurrell, and Potrykus (2001) reported the Goto, Yoshihara, Shigemoto, Toki, and Takaiwa introduction into rice of a transgene for this particular (1999) report improving the iron content of rice by heat-stable phytase from Aspergillus fumigatus; the transferring the entire coding sequence of the soybean transgene increased the level of phytase activity by 130- ferritin gene into a Japonica rice. The introduced ferri- fold. Unfortunately after expressing the gene in the tin gene was expressed under the control of a rice seed- grain, the phytase was no longer stable to heat and lost storage protein glutelin promoter, to mediate the accu- its activity on boiling. mulation of iron specifically in the grain. The transgenic A new approach is now under investigation in which seeds stored up to three times more iron than normal the A. fumigatus phytase gene would break down phy- seeds. Iron levels in the whole (unmilled) seeds of tate during seed maturation [when pH levels (6–7) the transformants varied from 13 to 38 mg/kg (ppm); would be conducive to phytase activity]. Fusing the pooled mean values were 23 mg/kg for transformants globulin promoter to the phytase gene, which tests have and 11 mg/kg for non-transformants. The average shown is expressed only in the endosperm of rice, which iron content in the endosperm was 3.4 mg/kg in the is consumed after milling, should prevent seed germina- transformant and 1.6 mg/kg in the non-transformant. tion being compromised (after harvesting and replanting) This underscores the importance of determining where owing to low phosphorus content. The hope is that the in endosperm the iron (and other trace minerals) are phosphorus in the outer layers of the seed (which is milled deposited and how mineral levels are affected by milling. away for consumption but not for planting) would remain Trace minerals cannot be synthesised by plants and unaffected (Lucca, Hurrell, & Potrykus, 2002). must be transported from the soil, through the plant and to the seed. Several processes and genes may be Increasing levels of compounds that improve absorption involved. The authors speculate that the amount of and utilisation of nutrients. Levels of , which is an iron accumulation is restricted by transport of iron to important, essential and limiting amino acid in rice and the ferritin , rather than simply by levels which might promote the uptake of trace minerals, can of ferritin protein. Thus, it may be possible to store lar- be improved by transgenic methods (Datta & Bouis, ger amounts of iron in the ferritin molecule by co-inte- 2000). Introduction of two bacterial genes, expressing grating the ferritin gene and the iron reductase-like DHSPS (dihydrodipicolinic acid synthase) and AK transporter gene. Robinson, Procter, Connolly, and (aspartokinase) , encoded by the Corynebacter- Guerinot (1999) report a newly discovered ferric-chelate ium dapA gene and a mutant Escherichia coli lysC gene, reductase gene, which allows plants to absorb more has enhanced lysine levels about five-fold in canola and iron from the soil, thus introducing the possibility of soybean seeds (Falco et al., 1995). widening the scope of rice varieties with high iron uptake. A doubling of the iron content in rice using a ferritin Adding beta-carotene. Beta-carotene, a precursor of gene derived from Phaseolus vulgare has been reported vitamin A, does not occur naturally in the endosperm of (Gura, 1999). Metallothionine was also expressed in the rice. Ye et al. (2000) have reported generating transgenic rice grain, increasing the cysteine content seven-fold. plants that produce grain with yellow-coloured endo- 198 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 sperm. Biochemical analysis confirmed that the colour women who would cross above the threshold of 12 g/dl represents beta-carotene (provitamin A). The reported haemoglobin as a result of consuming biofortified rice. level of beta-carotene in one gram of the dry, uncooked Women who remained below this threshold presumably transformed rice (Golden Rice) is 1.6 mg. Research is pre- would also derive some benefit from a 50% increase in sently underway to increase the level of beta-carotene in iron intakes. transformed rice, with promising ‘proof of concept’ results Biofortified varieties may reach undernourished in model systems (Beyer & Potrykus, 2001). people for a cost of only US $0.02–0.03 per person per year (Hunt, 2002), compared with a cost of US According to Ye et al. (2000), psy (cloned from Nar- $0.12 for commercial iron fortification (see Section cissus pseudonarcissus; Schledz et al., 1996), cryt1 2.2.1) and costs exceeding US $3.00 per person for (cloned from Erwinia uredovora; Misawa et al., 1993), iron supplements (World Bank, 1994). In the study and the lyc gene have been introduced into the rice, by Bhargava et al. (2001), the effect of iron supple- driven by the endosperm specific glutelin promoter ments in reducing anaemia levels was estimated to be (Gt1). Crt1 was fused to the transit peptide (tp) three times as strong as that of biofortified rice. sequence by the pea Rubisco small subunit (Misawa et Given that, per person reached, the cost of iron sup- al., 1993). The insertion of a multiple gene cassette is a plements is more than 100 times the cost of biofortified remarkable accomplishment, considering that most rice (i.e. US $3.00 compared with

2.5. Knowledge gaps in breeding for iron- and 2.5.3. Relative efficiency of transgenic and beta-carotene-dense rice conventional breeding methodologies Much experience has been accumulated with con- 2.5.1. The genotype factors that optimally determine ventional breeding and it continues to become more bioavailability efficient, in part owing to new techniques developed Determining the bioavailability to humans of micro- through the use of biotechnology. Yet, clearly the nutrients in plant foods depends on a myriad of factors, capability to move genes across species holds great which interact to determine the ultimate bioavailability potential, as demonstrated by the examples presented of a particular micronutrient to an individual, eating a above for rice, to accomplish goals that cannot be mixed diet, within a given environment (Fairweather- attained with conventional breeding. As experience is Tait & Hurrell, 1996; Welch, 2002). These factors gained with biotechnology, development of transgenic include the combination of nutrients, antinutrients, and varieties will become more efficient and cost-effective. absorption enhancers present in the nutrient enhanced It is difficult if not impossible to determine how rice and the meal in which it is eaten. Because of this investments should best be allocated between con- complexity, the data obtained using in vitro systems, ventional breeding, which will give benefits now, and animal models and test meals are always ambiguous transgenic methods, which will generate future benefits. (House, 1999; Van Campen & Glahn, 1999). Only data obtained on reducing the prevalence of micronutrient deficiencies, using feeding trials in test populations 2.5.4. Food and nutrient intakes stratified by country, under free living conditions, can delineate the actual urban-rural areas, and socioeconomic class efficacy of using micronutrient-enriched varieties of A rigorous ex ante evaluation of the benefits of bio- plant foods as an intervention tool. However, it is fortification requires the following: impractical to test, in this way, the bioavailability of selected micronutrients, in the numerous genotypes of . data on micronutrient status for various categories staple plant foods that can be generated in plant of individuals (e.g. by age, gender, income class, breeding programs (Graham et al., 2001; Graham & geographical location), matched with Welch, 1996). The ultimate proof of the biofortification . detailed knowledge of their food intakes and strategy will lie in effectiveness studies undertaken in . a reliably estimated empirical relationship, which areas where nutritionally improved varieties will be ‘explains’ observed micronutrient status as a func- introduced. tion of accurately measured levels of nutrients and other compounds in the diets.

2.5.2. Consumer acceptance A first attempt at such a study is described above There are various potential barriers to the adoption, (Section 2.3.2); however mismeasurement of food for example, of Golden Rice. intakes and nutrient content probably leads to an underestimation of the benefit of dietary quality on . It is yellow in colour, whereas Asian consumers micronutrient status. who stand to benefit the most from its introduc- tion are used to eating white rice. 2.5.5. Unintended effects . There may be consumer acceptance issues, poten- When several nutrients are lacking in diets and a sin- tially related to safety, ethics and localisation of gle nutrient is added in significant quantities, it is the decision-making process in agricultural devel- unclear what the nutritional outcome will be, in the light opment and associated processes. of important interactions among nutrients, which are . There may be concerns that technological solu- not fully understood. It will be important to check that tions used in isolation will exclude alternative there are no negative, unintended consequences of add- approaches, including for example, failure to har- ing one or a few nutrients to the diet or of altering the ness technology to social policy. levels of other compounds in foods.

Whether public initiatives can 2.6. Other potential contributions of GM crops address all of these concerns is open to question. Examples of successes in programs encouraging con- Sections 2.2–2.5 have sought to place the effort to sumers to switch from white to yellow or orange vari- breed for transgenic iron- and beta- carotene-dense rice 202 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209

Table 2.1. Genetic modification intended to enhance the nutritive value of food crops Nutritive component Target crop Targeted gene product References

Fats and oils Soybean Omega-3- (Kinney, 1996) Canola Stearidonic acid (SDA) (Voelker, 1997; Ivy, Beremond, & Thomas, 1998; Jalani, Cheah, Rajanaidu, & Darus, 1997) Sunflower Docosahexaenoic (Knutzon, 2000)

Protein Rice Beta-phaseolin (Zheng, Sumi, Tanaka, & Murai, 1995) Soybean enriched (Kim, Kamiya, Sato, Utsumi, & Kito, 1990) glycinin Sweet Essential amini acid (Katsube et al., 1999) rich protein

Carbohydrate Potato Amylose and amylopectin (Visser et al., 1991) structure/ratio Cassava Amylose and amylopectin (Visser et al., 1997) structure/ratio Banana Amylose and amylopectin (Schwall et al., 2000) structure/ratio

Carotenoids and Fruits and Beta-carotene (Hauptman, Eschenfeldt, English, & Brinkhaus, 1997) vegetables Soybean Alpha- (Romer et al., 2000)

Table 2.2. Genetic modification intended to enhance the quality of food crops and foods Improved quality Target crop Targeted gene product References

Delayed ripening Fruits Reduced ethylene production (Theolgis & Sato, 2000) Vegetables Maintain cytokinin levels (Gan & Amasino, 1995; Amasino & Gan, 1996)

Enhanced appearance Fruits and Inhibit oxidase; (Bachem et al., 1994; Murata et al., 2000; Coetzer, vegetables inhibit browning Corsini, Love, Pavek, & Turner, 2001) Potatoes Inhibit UDP- pyrophosphorylase; (Secor, Borovkov, McClean, & Sowokinos, 1997 Inhibit breakdown

Extended functionality Wheat Protein modification of high molecular (Shewry, Tatham, Barro, Barcelo, & Lazzeri, 1995; weight glutenins; flour functionality. Blechl & Anderson, 1996; Barro et al., 1997; Shewry & Tatham, 1997; Vasil & Anderson, 1997) Potato Starch modification (amylose/amylopectin (Visser et al., 1991; Visser, Suurs, Steeneken, & ratios) Jacobson, 1997; Heyer, Lloyd & Kossmann, 1999) Maize Arrowroot

Enhanced sweetness Tomatoes Monellin (Pennarubia, Kim, Giovannoni, Kim, & Fischer, 1992) Lettuce Potato Cucumber Thaumatin (Scwacka et al., 1999)

Fats and oils Canola Increased stearic acid (Facciotti, Bertain, & Yuan, 1999) Cottonseed Increased stearic acid (Lui, Singh, & Green, 2000) Soybean Increased oleic acid (Lui & Brown, 1996) Canola Increased oleic acid (Mazur, Krebbers, & Tingey, 1999) H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 203 in the context of the need for such interventions in food products, such as margarines, containing phytos- developing countries, the likelihood of success, alter- terols or phytostanols have appeared on the market in native interventions, and costs and benefits. Europe and the USA to help lower elevated Various attempts to enhance the nutritional or poten- levels. The sources of these compounds include pine tree tial health benefits of crops or food ingredients, in other resin and soybeans. The content of phytosterols in oil- ways, have also been reported. A detailed analysis of seeds has been enhanced by genetic modification (Ven- other biotechnology-related research to improve the katramesh, 2000). Such an improvement could increase nutritional and health enhancing effects of food of rele- the availability of this new functional component so it vance to developed as well as developing countries is not could be included in more foods. given herein, although an overview of several of these It is easy to understand the consumer appeal of func- activities is presented below. The requirements for the tional foods that are claimed to prevent . For development and assessment of such GMFs will be simi- example, glucoraphanin, a glucosinolate found in Bras- lar to those discussed above for GM rice. Possible genetic sica vegetables, is hypothesised to have cancer-prevent- modification interventions of relevance to nutritional and ing effects in humans. It has been shown to induce quality factors are outlined in Tables 2.1 and 2.2. detoxification enzymes in the liver although it is unclear if that is the mechanism by which it could prevent can- 2.6.1. Enhancing nutritional value cer. Glucoraphanin is not present in foods in high con- Strategies similar to those described above for Golden centrations and it is found in foods, such as broccoli, Rice have been employed to develop other crops with that are not particularly popular with some consumers. enhanced macro- or micronutrient content. Some of Research is now being directed at increasing levels of these modified crops are listed in Table 2.1; however, glucoraphanin in certain vegetables. What effect this none of them has reached the stage of commercialisa- will have on the overall safety, flavour or acceptability tion, so it is uncertain what drawbacks or risks might be of food will be the subject of much investigation if such associated with each. plants are developed. are a class of compounds, including iso- 2.6.2. Non-nutritive active components flavones, anthocyanins, rutin, quercitin, and kaemp- There is considerable private sector and consumer ferol, that are synthesized from via interest in ‘functional foods’, that is foods with special chalcone synthase and chalcone isomerase. They are health benefits not associated with nutrients. This sec- present in fruits, vegetables, nuts and seeds. Flavonoids tion gives a brief insight into how biotechnology may be have strong activity; both short- and long- used to produce healthier foods. It should be empha- term effects in humans of elevated consumption have sised, however, that these new varieties are the subject yet to be demonstrated. It is hypothesised, but has not of research that is in its earliest stages. Much funda- yet been proved, that the health benefits associated with mental research needs to be done to substantiate the diets rich in fruits and vegetables may derive, in part at proposed health benefits and associated risks, prior to least, from intake of components such as flavonoids. It the development of products with enhanced phyto- has been difficult to convince consumers in some cul- chemical content. tures, particularly children, to eat recommended quan- It is now widely recognised that plants contain many tities of fruits and vegetables. An alternative may be to physiologically active components that have no classi- help increase the intake of components such as flavo- cally defined nutritional role, but may have positive or noids by enhancing their levels in fruits and vegetables, adverse effects on human health. Much as is the case through biotechnology. Recently, the gene for soybean with carotenoids and , consumers seem isoflavone synthase has been expressed in the laboratory ready to seek out and use new foods for which some model plant, Arabidopsis thaliana; the transformant or expectation has been described. Many of non-leguminous plant produced the -derived these are viewed as a ‘natural’ means to ensure good isoflavone, genestein (Jung et al., 2000). Also the gene health. For the present, there are only a few food com- encoding chalcone isomerase has been isolated from ponents that sound evidence links positively to health petunia and inserted into tomato (Muir et al., 2001). outcomes, as is the case, for example, for some phytos- Paste processed from the transformed tomatoes con- terols (discussed below. Nonetheless, the pathways by tained up to 1.9 mg flavonols per gram dry weight, a 21- which some of these compounds are synthesised are fold increase compared with wild controls. Further- being elucidated so that ultimately their levels can be more, there was no negative effect on the plants and no manipulated. This has given rise to the new field called undesirable flavours developed in the paste product. ‘nutritional ’ or ‘metabolic engineering’ (Del- It is widely assumed that consumers will readily laPenna, 1999, 2001). accept functional foods, as people will perceive there is a Plant phytosterols, such as beta-sitosterol, were once benefit to health associated with such products. How- used as cholesterol-lowering drugs. Recently, functional ever, some psychological factors are important determi- 204 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 nants of food choices, and there are inter-individual and fact, the very first product of biotechnology to be cross-cultural differences in attitudes. For example, approved as a food was designed to enhance freshness. consumer research has demonstrated that, very gen- Softening of tomatoes can be delayed by insertion into erally, older Americans are more positive towards tomatoes of an antisense mRNA that inhibits synthesis ‘functional foods’ than are younger Europeans. Con- of an enzyme, polygalacturonase, that breaks down sumers are more tolerant of the enrichment or fortifica- pectin. The resulting ‘Flavr SavrTM’ tomato was sold tion of foods with substances that they already contain as whole fresh in supermarkets while a similar than enrichment of foods with novel substances. Indivi- tomato was used in processed tomato products in the dual differences in barriers to dietary change have also UK (Roller & Harlander, 1998). The products have been identified. These include: ‘food neophobia’; the been withdrawn from the market because they were extent to which people are fatalistic about developing unprofitable. disease and do not adopt dietary strategies to prevent illness; and cultural factors that determine . Other barriers to dietary change include factors like 2.6.4. Removing allergens and antinutrients ‘optimistic biases’, in which people rate their own risk of The primary food allergens in a plant are frequently developing illnesses as less than people with whom they major . One approach to reducing allergenicity compare themselves. Such psychological barriers have is to knock out the of the offending pro- been shown to influence the extent to which individuals tein. A second approach is to modify the structure of adopt healthy behaviours (such as healthy food choi- the offending protein so that it no longer contains the ces), in line with recommendations (Frewer, Scholderer, epitopes responsible for the undesirable immune & Lambert, in press). responses that result in allergic signs and symptoms. In order to succeed, the development and use of The first approach has been applied to rice. The content functional foods should be based on documented effi- of the major allergenic protein in rice has been success- cacy and should take account of diverse needs and fully reduced; however, it is not known if this results in requirements of different populations and demographic decreased allergenicity in humans (Tada et al., 1996). groups, as well as cultural factors that determine Peanut allergen (Bannon, Shin, Maleki, Kopper, & food choices. In broad terms, simply providing infor- Burks, 1999) and potato allergen (Alibhai et al., 2000; mation about health benefits is unlikely to be an Astwood, Alibhai, Lee, Fuchs, & Sampson, 2000) have influential strategy for changing well-established con- been modified by protein engineering to remove epi- sumer behaviours. topes associated with allergenicty. A more general method of disarming potential food allergens is also being tested (Buchanan et al., 1997). Thioredoxin is a 2.6.3. Improving quality traits regulatory disulfide protein that is widely distributed in Biotechnology offers the possibility to produce grains, . It has been found to reduce disulfide bonds in fruits and vegetables that retain their fresh appearance allergens, and the reduced allergens are less allergenic. longer and have a longer useful shelf life than non- Research is underway to determine if insertion of a gene modified products. Other targets for modification for thioredoxin biosynthesis into wheat will reduce its include alterations in flavour, taste, texture and viscos- allergenicity without interfering with the functionality ity. Changes can be directed at alteration of the expres- of the wheat proteins. sion of a key enzyme or introduction of a new protein Members of the Brassica family, such as , or enzymatic activity. For example, antisense RNA has Brussels sprouts and broccoli, rapeseed and mustard frequently been employed to block the synthesis of key contain a family of compounds called glucosinolates. enzymes. Some examples, representative of the scope of Glucosinolates can be hydrolysed to bitter tasting and the modifications that have been reported, are presented potentially toxic isothiocyanates. Extensive plant in Table 2.2. breeding was required to produce varieties of rapeseed For example, fresh fruits and vegetables are relatively and mustard with greatly reduced levels of glucosino- perishable commodities that have limited shelf . lates. The meal remaining after oil extraction from these Moreover, fresh produce and fruits must often be varieties can be used in animal feed. Glucosinolates are picked in a green or unripened state in order to allow part of the plant’s defence system against insect pests time for shipping, marketing and, ultimately, ripening and pathogens. Attempts are now being made to prior to sale. Plant breeders have sought for many develop plants that have high glucosinolate levels in years, with only limited success, to develop varieties that and seedpods but much reduced levels in the oil- have delayed ripening and extended shelf lives. The seeds (Vageeshbabu & Chopra, 1997). introduction of molecular breeding techniques has Solanine and chaconine are naturally occurring gly- allowed the targeting and modification of pathways coalkaloid toxins that are found in potatoes and other involved in ripening and senescence in certain crops. In solanaceous plants. While toxic to humans, the com- H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 205 pounds are destroyed by cooking. It has been reported this chapter will be segregated during cultivation and that insertion of an invertase gene from yeast into offered for sale to consumers, based on their enhanced potato reduces the glycoalkaloid content (Engel, Blaas, nutritional or quality characteristics. Gabriel, & Beckman, 1996). The exact mechanism for Any type of crop whose nutritional composition has this inhibition is not known and further seeks to been altered, whether by traditional or biotechnological establish if the effect is caused by metabolic interference means, must be shown to be stably maintained; fur- with the moieties needed for biosynthesis of gly- thermore the crop should not interfere with or nega- coalkaloids. It is also possible to use antisense RNA to tively impact on other cropping systems or the block synthesis of a gene that codes for a key enzyme in environment. It will also be important to monitor the glycoalkaloid synthesis. nutritional status of populations that have adopted new Fumonisin is a mycotoxin that is produced by the fun- nutritionally enhanced crops. gus Fursarium. It accumulates in maize that has become Also, any type of crop whose nutritional composition infected at the site of damage by such as the Eur- has been altered, whether by traditional or biotechno- opean corn borer. Although the fumonisin content of logical means, should pose no unique environmental or maize is approximately proportional to the level of insect food risk. The most significant challenge will be to pre- damage, the temperature and humidity of storage can dict changes in the dietary intake of specific nutrients affect the level of mycotoxin accumulation. Levels of when these products are introduced into the market- fumonisin in grain should be carefully controlled since place. It may be inadvisable to market products that fumonisin B1 is a possible human carcinogen (IARC, contain elevated levels of nutrients that could be toxic 2002). It has been linked to oesophageal cancer in humans to the 99th percentile of consumers. National food con- who consume high levels of fumonisin-contaminated sumption surveys may be useful in changes maize. Fumonisin causes liver cancer in rats (Gelderblom, in dietary intake. Abel, et al.,2001) and liver and kidney damage in non- human primates (Gelderbom, Seier, et al.,2001); it is also known to be acutely toxic to livestock. De-esterase genes 2.8. Conclusions have been transferred from yeast into maize for the pur- The following lessons may be drawn concerning the pose of detoxifying fumonisin (Duvick, 2001). potential usefulness of biotechnology in helping to pro- As Bt-maize is resistant to attack by insect pests, vide more nutritious foods in developing countries. levels of fumonisin in Bt-maize are consistently greatly reduced over levels observed in its conventional coun- . To be of value plant breeding has to be demon- terpart (Cahagnier & Melcion, 2000; Dowd, 2000; strated to be safe (see below) and more cost-effec- Munkvold, Hellmich, & Rice 1999). In a 3-year study tive than alternative interventions already in place conducted in northern Italy, where fumonisin con- to reduce micronutrient undernutrition. Such cost- tamination of corn is a major problem, fumonisin levels effectiveness is anticipated, in large measure in Bt corn were greatly reduced compared with tradi- because of the far-reaching impacts of plant tional hybrids (Pietri & Piva, 2000). Reductions in the breeding. A relatively small, fixed, initial invest- fumonisin content of maize represent a significant ment in research could benefit the health of mil- enhancement in food and feed safety and will also lions of poor people in developing countries all reduce post-harvest losses associated with the destruc- over the world, and at the same time could tion of contaminated grain improve agricultural productivity on lands that are presently among the least productive. Nutrient- dense varieties of crops can be developed for a 2.7. Standards for food use fraction of the recurrent estimated annual costs of Many of the potential GM products that are descri- supplementation programmes in developing coun- bed herein have altered macro- or micronutrient com- tries (for example US $1.65 billion for vitamin A position. Modifications are intended to enhance supplementation programmes) and can reach far nutritional value or alter the quality characteristics of more people, as the benefits can be extended across the food. These new plant varieties contain altered con- countries and time. tents of macronutrients, micronutrients or non-nutritive . There should be aspects of the breeding strategy compounds of special interest that are ordinarily con- for which biotechnology is superior to conven- sumed in the human diet. tional breeding techniques. For rice, this is the case These new crops are intended for distinct uses. Pro- for adding beta-carotene-related and heat-stable ducts such as Golden Rice are intended to replace or phytase genes. In the long run, as more is under- partially replace a commodity crop, in regions where stood about the factors driving translocation of populations consuming rice are at risk of vitamin A minerals in plants, biotechnology may also be a deficiency. Many of the plant developments described in more efficient way to increase trace mineral density. 206 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209

. Where biotechnology is superior to conventional its most important contribution to reducing malnutri- plant breeding, it must be recognised that the same tion. However, this will require several decades to be conditions as that apply to products developed via realised, informed government policies, and a relatively conventional plant breeding, must also be met, as large investment in agricultural research and other follows: public and on-farm infrastructure. In conceptualising solutions for a range of nutritional  there should be no serious, negative agronomic deficiencies, interdisciplinary communication between consequences associated with the characteristic plant scientists and human nutrition scientists holds being added; great potential. Human nutritionists need to be  any noticeable changes in the colour, taste, informed, for example, about the extent to which the texture, cooking qualities, and other features vitamin and mineral density of specific foods, as well as associated with the characteristic being added compounds that promote and inhibit their bioavail- should be acceptable to the consumer; ability, can be modified through plant breeding. Plant  the characteristic being added should result in a breeders need to be aware of both the major influence measurable improvement in the nutritional sta- that agricultural research may have had on nutrient tus of the malnourished, target population; and utilisation in the past (e.g. the bioavailability of trace  there should be no unacceptable nutritional minerals in modern varieties versus bioavailability in effects. traditional varieties), and the potential of plant breeding for future improvements in nutrition and health. The conditions, relating to safety, acceptability and efficacy, in particular, have yet to be firmly established. Nutritionally improved transgenic foods have not been fully developed and tested for their potential to improve 2.9. References micronutrient status, even using in vitro techniques and Administrative Committee on Coordination, Subcommittee on animal models, let alone in human subjects with micro- Nutrition, & International Food Policy Research Institute. (2000). nutrient deficiencies. Fourth report on the world nutrition situation. Geneva: United Definitive proof of the benefit of nutritionally Nations. improved, transgenic foods obviously depends on fur- Adrizal, P. E. P., & Sell, J. L. (1996). Utilization of defatted rice bran ther development, release and eventual impact evalua- by broiler chickens. Poultry Science, 75, 1012–1017. Alibhai, M., Astwood, J., Joyce, E., Pershing, J., Sampson, H., & Pur- tion, all of which are many years into the future. , J. (2000). Re-engineering patatin (Sol t 1) protein to eliminate Nevertheless, in the shorter term, lessons learned IgE binding. Journal of Allergy and Clinical , through initial experiences with conventional breeding 105(Suppl.), S79. efforts show just how cost-effective a biofortification Amasino, R., & Gan, S. (1996). Transgenic plants with altered senes- strategy can be. Clearly, the nutritional quality of staple cence characteristics (International Patent Publication No. WO foods can be substantially improved using transgenic 96/29858). Geneva: World Intellectual Property Organization. Astwood, J., Alibhai, M., Lee, T., Fuchs, R., & Sampson, H. (2000). methods compared with what can be accomplished Identification and characterization of IgE binding epitopes of using conventional breeding. Knowledge in the area of patatin, a major food allergen of potato. Journal of Allergy and should expand rapidly in the Clinical Immunology, 105(Suppl.), S184. future and more efficient techniques for producing Bachem, C., Speckmann, G., van der Linde, P., Verheggen, F., Hunt, transgenic plants will be developed. There are poten- M., Steffens, J., & Zabeau, M. (1994). Antisense expression of tially substantial benefits to the poor in developing polyphenol oxidase genes inhibits enzymatic browning in potato tubers. Bio-Technology, 12, 1101–1105. countries in relation to costs. Bannon, G., Shin, D., Maleki, S., Kopper, R., & Burks, A. W. (1999). Characteristics of food, such as appearance, taste, and Tertiary structure and biophysical properties of a major peanut colour, which are important to consumers in both devel- allergen, implications for production of a hypoallergenic protein. oped and developing countries, can also be improved International Archives of Allergy and Immunology, 118, 315–316. through biotechnology; however, such research currently Barro, F., Rooke, L., Bekes, F., Gras, P., Tatham, Fido, R., Lazzeri, P., probably benefits wealthy consumers in developed coun- Shewry, P., & Barcelo, P. (1997). Transformation of wheat with high molecular weight subunit genes results in improved func- tries more than poor consumers in developing countries. tional properties. Nature Biotechnology, 15, 1295–1299. Ultimately, good nutrition depends on adequate Beard, J. L., Burton, J. W., & Theil, E. C. (1996). Purified ferritin and intakes of a range of nutrients and other compounds, in soybean meal can be sources of iron for treating iron deficiency combinations and levels that are not yet completely in rats. Journal of Nutrition, 126, 154–160. understood. Thus, the best and final solution to elim- Beaton, G. H., Martorell, R., Aronson, K. J., Edminston, B., McCabe, inating undernutrition as a public health problem in G., Ross, A. C., & Harvey, B. (1993). Effectiveness of vitamin A supplementation in the control of young child morbidity and developing countries is to provide increased consump- mortality in developing countries (ACC/SCN State of the Arts tion of a range of non-staple foods. By reducing the cost Series, Nutrition and Policy Discussion Paper No 13). Geneva, of producing food, biotechnology will, perhaps, make Switzerland: Administrative Committee on Coordination, Sub- H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 207

committee on Nutrition Available [Dec 2002] from; http:// Facciotti, M., Bertain, P., & Yuan, L. (1999). Improved stearate phe- www.unsystem.org/scn/. notype in transgenic canola expressing a modified acylacyl car- Beyer, P., & Potrykus, I. (2001). Golden rice: proof of concept and rier protein thioesterase. Nature Biotechnology, 17, 593–597. beyond. Seeds of Health, 1, 2 and 10. Fairweather-Tait, S., & Hurrell, R. F. (1996). Bioavailability of minerals Beyer, P., Salim, A.-B., Xudong, Y., Lucca, P., Schaub, P., Welsch, R., and trace elements. Nurition Research Reviews, 9, 295–324. & Potrykus, I. (2002). ‘‘Golden Rice’’: introducing the B-carotene Falco, S. C., Guida, T., Locke, M., Mauvais, J., Sanders, C., Ward, R. biosynthesis pathway into rice endosperm by genetic engineer- T., & Webber, P. (1995). Transgenic canola and soybeans seeds ing to defeat vitamin A-deficiency. Journal of Nutrition, with increased lysine. Bio-Technology, 13, 577–582. 132(Suppl.), 506S–510S. Farrell, D. J., & Martin, E. A. (1998). Strategies to improve the Bhargava, A., Bouis, H., & Scrimshaw, N. (2001). Dietary intakes and nutritive value of rice bran in poultry diets. III. The addition of socioeconomic factors are associated with the haemoglobin inorganic phosphorus and a phytase to duck diets. British Poul- concentration of Bangladeshi women. Journal of Nutrition, 131, try Science, 39, 601–611. 758–764. Frewer, L., Scholderer, J., & Lambert, N. (in press). Consumer Blechl, A., & Anderson, O. (1996). Expression of a novel high- acceptance of functional foods: issue for the future. British Food molecular-weight glutenin subunit gene in transgenic wheat. Journal. Nature Biotechnology, 14, 875–879. Gan, S., & Amasino, R. (1995). Inhibition of senescence by Bouis, H., se la Brie` re, L., Guitierrez, K., Hallman, N., Hassan, O., autoregaulation production of cytokinin. Science, 270, 1986– Hels, W., Quabili, A., Quisumbing, S., Thilsted, Z., Zihad, Z., & 1988. Zohir, S. (1998). Commercial vegetable and polyculture fish pro- Garcia-Casal, M. N., Layrisse, M., Baron, M. A., Arguello, F., Llovera, duction in Bangladesh: impacts on income, household resource D., Ramirez, J., Leets, I., & Tropper, E. (1998). Vitamin A and b- allocation and nutrition. Washington DC: International Food carotene can improve nonheme iron absorption from rice, Policy Research Institute. wheat and corn by humans. Journal of Nutrition, 128, 646–650. Bouis, H., Graham, R., & Welch, R. (2000). The Consultative Group Gelderblom, W. C. A., Seier, J. V., Snijman, P. W., Van Schalkwyk, on International Agricultural Research (CGIAR) Micronutrients D. J., Shephard, G. S., & Marasas, W. F. O. (2001). Toxicity of Project: justification and objectives. Food and Nutrition Bulletin, culture material of Fusarium verticillioides strain MRC 826to 21, 374–381. nonhuman primates. Perspectives, Buchanan, B., Adamidi, C., Lozano, R., Yee, B., Momma, M., 109(Suppl. 2), 267–276. Kobrehel, K., Ermel, R. M., & Frick, O. (1997). Thioredoxin-linked Gelderblom, W. C. A., Abel, S., Smuts, C. M., Marnewick, J., Mar- mitigation of allergic responses to wheat. Proceedings of the asas, W. F. O., Lemner, E. R., & Ramljak, D. (2001). Fumonisin- National of Sciences of the United States of America, 94, induced hepatocarcinogenesis: mechanisms related to cancer 5372–5377. initiation and promotion. Environmental Health Perspectives, Cahagnier, B., & Melcion, D. (2000). Mycotoxines de Fusarium dans 109(Suppl. 2), 291–300. les mais-grains a la recolte: relation entre la presence d’insects Glahn, R. P., Lee, O. A., & Miller, D. D. (1999). In vitro digestion/ (pyrale, sesamie) et la teneur en mycotoxines. In Proceedings of Caco-2 cell culture model to determine optimal ascorbic acid to the 6th international feed production conference, Piacenza, 27–28 Fe ratio in rice cereal. Journal of Food Science, 64, 925–928. November 2000. Goto, F. T., Yoshihara, T., Shigemoto, N., Toki, S., & Takaiwa, F. Coetzer, C., Corsini, D., Love, S., Pavek, J., & Turner, N. (2001). (1999). Iron fortification of rice seed by the soybean Ferritin Control of enzymatic browning in potato (Solanum tuberosum gene. Nature Biotechnology, 17, 282–286. L.) by sense and antisense RNA from tomato polyphenol oxi- Graham, R. D., & Welch, R. M. (1996). Breeding for staple-food crops dase. Journal of Agricultural and Food , 49, 652–657. with high micronutrient density: long-term sustainable agricultural Datta, S., & Bouis, H. E. (2000). Application of biotechnology to solutions to hidden hunger in developing countries (Agricultural improving the nutritional quality of rice. Food and Nutrition Strategies for Micronutrients Working Paper 3). Washington, Bulletin, 21, 451–456. DC: International Food Policy Research Institute. de Pee, S., West, C. E., Permaesih, D., Martuti, S., Muhilal, ?., & Graham, R. D., Senadhira, D., & Ortiz-Monasterio, I. (1997). A Hautvast, J. G. A. J. (1998). Orange fruit is more effective than are strategy for breeding staple-food crops with high micronutrient dark-green, leafy vegetables in increasing serum concentrations density. Soil Science and Plant Nutrition, 43, 1153–1157. of retinol and beta-carotene in schoolchildren in . Graham, R. D., Senadhira, D., Beebe, S. E., Iglesias, C., & Ortiz- American Journal of , 68, 1058–1067. Monasterio, I. (1999). Breeding for micronutrient density in edible DellaPenna, D. (1999). Nutritional genomics: manipulating plant portions of staple food crops: conventional approaches. Field micronutrients to improve human health. Science, 285, 375–379. Crop Research, 60, 57–80. DellaPenna, D. (2001). Plant metabolic engineering. Plant Physiol- Graham, R. D., Welch, R. M., & Bouis, H. E. (2001). Addressing ogy, 125, 160–163. micronutrient malnutrition through enhancing the nutritional Dowd, P. (2000). Indirect reduction of ear moulds and associated quality of staple foods: principles, perspectives and knowledge mycotoxins in Bacillus thuringiensis corn under controlled and gaps. Advances in Agronomy, 70, 77–142. open field conditions: utility and limitations. Journal of Economic Gregorio, G. B. (2002). Progress in breeding for trace minerals in Entomology, 93, 1669–1679. staple crops (Abstract). J. Nutr., 132(special issue), 3. Duvick, J. (2001). Prospects for reducing fumonism contamination Guerinot, M. L. (2000). The green revolution strikes Gold. Science, of maize through. Environmental Health Perspectives, 109(Suppl. 287, 241–243. 2), 337–342. Gura, T. (1999). New genes boost rice nutrients. Science, 285, 994– Engel, K., Blaas, W., Gabriel, B., & Beckman, M. (1996). Modern 995. biotechnology in plant breeding: analysis of glycoalkaloids in Haas, J., del Mundo, A. M., & Beard, J. (2000). A human feeding trial transgenic potatoes. In G. R. Takeoka, R. Teranishi, P. J. Williams, of iron-enhanced rice. Food and Nutrition Bulletin, 21, 440–444. & A. Kobayashi (Eds.), Biotechnology for improved foods and Hagenimana, V., & Low, J. (2000). Potential of orange-fleshed sweet flavours (pp. 249–260). Washington: American Chemical potatoes for raising vitamin A intake in Africa. Food and Nutri- Society. tion Bulletin, 21, 414–418. 208 H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209

Hallberg, L. (1981). Bioavailability of dietary iron in man. Annual Martin, E. A., Nolan, J. C., Nitsan, Z., & Farrell, D. J. (1998). Strategies Review of Nutrition, 1, 123–127. to improve the nutritive value of rice bran in poultry diets. IV. Hauptmann, R., Eschenfeldt, W. H., English, J., & Brinkhaus, F. L. Effects of addition of fish meal and a microbial phytase to (1997). Enhanced carotenoid accumulation in storage organs of duckling diets on bird performance and amino acid digestibility. genetically engineered plants (United States Patent 5,618,988), British Poultry Science, 39, 612–621. Date Filed: 28/10/1994. Washington, DC: United States Patents Martinez-Torres, C., Renzi, M., & Layrisse, M. (1976). Iron absorption and Trademarks Office. by humans for hemosiderin and ferritin, further studies. Journal Heyer, A., Lloyd, J., & Kossmann, J. (1999). Production of modified of Nutrition, 106, 128–135. polymeric . Current Opinion in Biotechnology, 10, Mazur, B., Krebbers, E., & Tingey, S. (1999). Gene discovery and 169–174. product development for grain quality traits. Science, 285(5426), Holm, P. B., Kristiansen, K. N., & Pedersen, H. B. (2002). Transgenic 372–375. approaches in commonly consumed cereals to improve iron McLaughlin, M. J., Parker, D. R., & Clarke, J. M. (1999). Metals and and zinc content and bioavailability. Journal of Nutrition, macronutrients— issues. Field Crop Research, 60, 132(Suppl.), 514–516. 143–163. Horton, S., & Ross, J. (1998). Economic consequences of iron effi- Merryweather-Clarke, A. T., Pointon, J. J., Sherman, J. D., & Robson, ciency. Ottawa, Canada: The Micronutrient Initiative. K. J. (1997). Global prevalence of putative haemochromatosis. House, W. A. (1999). Trace element bioavailability as exemplified Journal of Medical , 34, 275–278. by iron and zinc. Field Crop Research, 60, 115–141. Misawa, N., Yamona, H., Linden, H., de Felipe, M. R., Lucas, M., Hunt, J. M. (2002). Reversing productivity losses from iron defi- Ikenga, H., & Sandmann, G. (1993). Functional expression of the ciency: the economic case. Journal of Nutrition, 132(Suppl 4), Erwinia uredovora biosynthesis gene crtl in transgenic plants 794–801. showing an increase of b-carotene biosynthesis activity and IARC. (2002). IARC Monographs on the evaluation of carcinogenic resistance to the bleaching herbicide Norflurazon. Plant Journal, risks to humans, vol 82, Some traditional herbal medicines, some 4, 833–840. mycotoxins, napthalene and styrene. Lyon, France: International Muir, S., Collins, G., Robinson, S., Hughes, S., Bovy, A., De Vos, C., Agency for Research on Cancer. van Tunen, A., & Verhoeyen, M. (2001). Overexpression of pet- Institute of Medicine, Food and Nutrition Board. (2001). Dietary unia chalcone isomerase in tomato results in fruit containing reference intakes for vitamin a, , arsenic, , increased levels of flavonols. Nature Biotechnology, 19, 470–474. , iodine, iron, , , , silicon, Munaro, F. A., Lopez, J., Lopez, S. E., & Rutz, F. (1996). Effect of and zinc. Washington, DC: National Academy Press. phytase on boiavailability of phosphorus in diets with defattaed Ivy, M. J., Beremond, P. D., & Thomas, T. L. (1998). Strategies for rice bran for broiler chickens. Revista da Sociedade Brasileira de modifying fatty acid composition in transgenic plants. Bio- Zootecnia, 25, 932–943. technology and Genetic Engineering Reviews, 15, 271–288. Munkvold, G., Hellmich, R., & Rice, L. G. (1999). Comparison of Jalani, B. S., Cheah, S. C., Rajanaidu, N., & Darus, A. (1997). fumonisin concentrations in kernels of transgenic Bt maize Improvement of palm oil through breeding and biotechnology. hybrids and nontransgenic hybrids. Plant Disease, 83, 130–138. Journal of American Oil Chemists’ Society, 74, 1451–1455. Murata, M., Haruta, M., Murai, N., Tanikawa, N., Nishimura, M., Jung, W., Yu, O., Lau, S., O’Keefe, D., Odell, J., Fader, G., & McGo- Homma, S., & Itoh, Y. (2000). Transgenic apple (Mal- nigle, B. (2000). Identification and expression of isoflavone syn- usÂdomestica) shoot showing low browning potential. Journal of thase, the key enzyme for biosynthesis of isoflavones in Agricultural and , 48, 5243–5248. . Nature Biotechnology, 18, 208–212. Murray-Kolb, L. E., Takaiwa, F., Goto, F., Yoshihara, T., Theil, E. C., & Katsube, T., Kurisaka, N., Ogawa, M., Maruyama, N., Ohtsuka, R., Beard, J. L. (2002). Transgenic rice as a source of iron for iron- Utsumi, S., & Takaiwa, F. (1999). Accumulation of soybean gly- depleted rats. Journal of Nutrition, 132, 957–960. cinin and its assembly with glutelins in rice. Plant , Murray-Kolb, L. E., Welch, R., Theil, E. C., & Beard, J. L. (2003). 120, 1063–1073. Women with low iron stores absorb iron form soybeans. Amer- Kim, C. S., Kamiya, S., Sato, T., Utsumi, S., & Kito, M. (1990). ican Journal of Clinical Nutrition, 77, 180–184. Improvement of nutritional-value and functional-properties of Nelson, T. S., Shieh, T. R., Wodzinski, R. J., & Ware, J. H. (1971). soybean glycinin by protein engineering. Protein Engineering, 3, Effects of supplemental phytase on the utilization of phytate 725–731. phosphorus by chicks. Journal of Nutrition, 101, 1289–1294. Kinney, A. J. (1996). Designer oils for better nutrition. Nature Bio- Pasamontes, L., Haiker, M., Wyss, M., Tessier, M., & van Loon, A. P. technology, 14, 946. (1997). Gene , purification and characterization of a heat- Knutzon, D. (2000). Polyunsaturated fatty acids in plants (Interna- stable phytase from the fungus Aspergillus fumigatus. Applied tional Patent Publication No. WO 99/64614, Date Filed: 6/10/ and Environmental , 63, 1696–1700. 1999). Geneva: World Intellectual Property Organization. Pennarubia, L., Kim, R., Giovannoni, J., Kim, S., & Fischer, R. (1992). Lucca, P., Hurrell, R., & Potrykus, I. (2001). Genetic engineering Production of the sweet protein monoellin in transgenic plants. approaches to improve the bioavailability and the level of iron Bio-Technology, 10, 561–564. in rice grains. Theoretical and Applied Genetics, 102, 392–397. Pietri, A., & Piva, G. (2000). Occurrence and control of mycotoxins Lucca, P., Hurell, R., & Potrykus, I. (2002). Fighting iron deficiency in maize grown in Italy. In Proceedings of the 6th international with iron-rich rice. Journal of the Amercian College of feed conference, food safety: current situation and perspectives in Nutrition, 21, 184S–190S. the European Community. Piacenza, Italy. 27–28 November, 2000, Lui, K. S., & Brown, E. A. (1996). Enhancing vegetable oil quality (pp. 226–236) through plant breeding and genetic engineering. Food Technol- Raboy, V. (1996). Cereal low phytic mutants: a ‘‘global’’ approach ogy, 50, 67–71. to improving mineral nutritional quality. Micronutrients and Lui, Q., Singh, S., & Green, A. (2000). Genetic modification of cotton Agriculture, 2, 15–16. seed oil using inverted-repeat gene-silencing techniques. In J. Rimbach, G., & Pallauf, J. (1993). Enhancment of zinc utilization L. Harwood, & P. J. Quinn (Eds.), Recent advances in the bio- from phytate-rich soy protein isolate by microbial phytase. chemistry of plant (pp. 927–929). London: Portland Press. Zeitschrift fu¨r Ernahrungswissenschaft, 32, 308–315. H.E. Bouis et al. / Trends in Food Science & Technology 14 (2003) 191–209 209

Robinson, N. J., Procter, C. M., Connolly, M. L., & Guerinot, M. L. Tyssandier, V., Lyan, B., & Borel, P. (2001). Main factors governing (1999). A ferric-chelate reductase for iron uptake from soils. the transfer of caretenoids from emulsion droplets tomi- Nature, 397, 694–697. celles. Biochimica and and Biophysica Acta, 1533, 285–292. Roller, S., & Harlander, S. (1998). Modern food biotechnology: UNICEF/UNU/WHO/MI Technical Workshop (1999). Preventing iron overview of key issues. In S. Roller, & S. Harlander (Eds.), Genetic deficiency in women and children: background and consensus on modification in the —a strategy for food quality key technical issues and resources for advocacy, planning and improvement. London, UK: Blackie Academic and Professional. implementing national programmes. Boston MA: International Romer, S., Fraser, J., Kiano, C., Shipton, C., Misawa, W., Schuch, W., Nutrition Foundation: Ottawa, Canada: The Micronutrient & Bramley, P. (2000). Elevation of the provitamin A content of Initiative transgenic tomato plants. Nature Biotechnology, 18, 666–669. Vageeshbabu, H., & Chopra, V. (1997). Genetic and biotechnologi- Rosegrant, M. W., Paisner, M., Meijer, S., & Witcover, J. (2001). cal approaches for reducing glucosinolates from rapeseed-mus- Global food projections to 2020: emerging trends and alternative tard meal. Journal of Plant Biochemistry and Biotechnology, 6, 53– futures. Washington DC: International Food Policy Research 62. Institute. Van Campen, D. R., & Glahn, R. P. (1999). Micronutrient bioavail- Schledz, M., Al-Babili, S., Lintig, H., Haubruck, S., Rabbani, S., Klei- ability techniques: accuracy, problems and limitations. Field nig, H., & Beyer, P. (1996). Phytoene synthase from Narcissus Crop Research, 60, 93–113. pseudonarcissus: functional expression, galactolipid require- Vasil, I., & Anderson, O. (1997). Genetic engineering of wheat glu- ment, topological distribution in chromoplasts and induction ten. Trends in Plant Science, 2, 292–297. during flowering. Plant Journal, 10, 781–792. Venkatramesh, M. (2000). Transgenic plants containing altered levels Schwall, G., Safford, R., Westcott, R., Jeffcoat, A., Tayal, A., Shi, Y.- of sterol compounds and (International Patent Pub- C., Gidley, M., & Jobling, S. (2000). Production of very-high-amy- lication No. WO 00/61771, Date Filed: 19/10/2000). Geneva: lose potato starch by inhibition of SBE A and B. Nature Bio- World Intellectual Property Organization. technology, 18, 551–554. Visser, R., Somhorst, I., Kuipers, G., Ruys, N., Feenstra, W., & Scwacka, M., et al. (1999). Transgenic cucumber plants expressing Jacobsen, E. (1991). Inhibition of the expression of the gene for the thaumatin gene. In Food biotechnology—proceedings of an granule-bound starch synthase in potato by antisense con- international symposium, Zakopane, Poland. Amsterdam, Neth- structs. Molecular and General Genetics, 225, 289–296. erlands: Elsevier Visser, R., Suurs, L., Steeneken, P., & Jacobsen, E. (1997). Some Secor, G., Borovkov, A. Y., McClean, P. E., & Sowokinos, J. R. (1997). physicochemical properties of amylose-free potato starch. Modulation of sugar content in plants (United States Patent Starch/Staerke, 49, 443–448. 5,646,023) Date Filed: 8/7/1997). Washington DC: United States Voelker, T. (1997). Transgenic manipulation of edible oilseeds. In Patents and Trademarks Office. T. Johns, & J. T. Romeo (Eds.), Functionality of Food Phytochem- Senadhira, D., & Graham, R. D. (1999). Genetic variation in iron and zinc icals (pp. 223–236). New York: Plenum Press. concentrations in brown rice. Micronutrients in Agriculture, 3, 10–12. Welch, R., & Graham, R. (1999). A new paradigm for world agri- Sharma, D. C. (2001). UN vitamin A campaign in India under fire. culture: meeting human needs, productive, sustainable nutri- Lancet, 358(9295), 1791. tious. Field Crop Research, 60, 1–10. Shewry, P., Tatham, A., Barro, F., Barcelo, P., & Lazzeri, P. (1995). Welch, R. M. (1986). Effects of nutrient deficiencies on seed pro- Biotechnology of breadmaking: unraveling and manipulating the duction and quality. Advances in Plant Nutrition, 2, 205–247. multi-protein gluten complex. Bio-Technology, 13, 1185–1190. Welch, R. M. (1993). Zinc concentrations and forms in plants for Shewry, P., & Tatham, A. (1997). Biotechnology of wheat quality. humans and animals. In A. D. Robson (Ed.), Zinc in soils and Journal of the Science of Food and Agriculture, 73, 397–406. plants (pp. 183–195). Kluwer Academic Publishers, Boston MA. Skikne, B., Fonzo, D., Lynch, S. R., & Cook, J. D. (1997). Bovine fer- Welch, R. M., William, A., House, A. H., Beebe, S., Senadhira, D., ritin bioavailabilty in man. European Journal of Clinical Investiga- Gregoria, G., & Cheng, Z. (2000). Testing iron and zinc bioavai- tions, 27, 228–233. labilty in genetically enriched bean (Phaselous Vulgaris L.) and Smith, J.C. (1996). The vitamin A–Zinc connection. In Micro- rice (Oryza Sativa L.) using a rat model. Food and Nutrition Bul- nutrients and agriculture. Washington, DC: Federation of Amer- letin, 21, 428–433. ican Scientists Welch, R. M. (2002). Breeding strategies for biofortified staple plant Tada, Y., Nakase, M., Adachi, T., Nakamura, R., Shimada, H., Taka- foods to reduce micronutrient malnutrition globally. Journal of hashi, M., Fujimura, T., & Matsuda, T. (1996). Reduction of 14-16 Nutrition, 132(Suppl.), 495–499. kDa allergenic proteins in transgenic rice plants by antisense Wise, A. (1995). Phytate and zinc bioavailability. International Jour- gene. FEBSLetters , 391, 341–345. nal of Food Science and Nutrition, 46, 53–63. Taylor, P. G., Martinez-Torres, C., Romano, E. L., & Layrisse, M. World Bank. (1994). Enriching lives: overcoming vitamin and mineral (1986). The effect of cysteine-containing peptides released dur- malnutrition in developing countries (Development in Practice ing meat digestion on iron absorption in humans. American Series). Washington DC: The World Bank. Journal of Clinical Nutrition, 43, 68–71. Ye, X., Al Babili, S., Kloeti, A., Zhang, J., Lucca, P., Beyer, P., & Teichmann, H. F., Lopez, J., & Lopez, S. E. (1998). Effect of phytase Potrykus, I. (2000). Engineering the provitamin A (b-carotene) on the bioavailability of phosphorus in diets with rice bran for biosynthetic pathway into (carotenoid-free) rice endosperm. broilers. Revista Braasileira de Zootechnia, 27, 338–344. Science, 287, 303–305. Theil, E. C., Burton, J. W., & Beard, J. L. (1997). A sustainable solution Yi, Z., Kornegay, E. T., & Veit, H. P. (1996). Supplemental microbial for dietary iron deficiency through plant biotechnology and phytase improves zinc utilization in broilers. Poultry Science, 75, breeding to increase seed ferritin control. European Journal of 540–546. Clinical Nutrition, 21(Suppl. 4), S28–S31. Zheng, A., Sumi, K., Tanaka, K., & Murai, N. (1995). The bean Theologis, A., & Sato, T. (2000). Control of fruit ripening through seed storage protein b-phaseolin is synthesized, processed genetic control of ACC synthase synthesis (United States Patent and accumulated in the vacuolar type-II protein bodies 6,156,956, Date Filed: 2/3/1998). Washington DC: United States of transgenic rice endosperm. Plant Physiology, 109, 777– Patents and Trademark Office. 786.