from the association Position of the American Dietetic Association: Health Implications of Dietary Fiber ical studies of effectiveness before should consume adequate amounts of ABSTRACT selecting functional fibers in dietetics dietary fiber from a variety of plant It is the position of the American Die- practice. foods. tetic Association that the public should J Am Diet Assoc. 2008;108: consume adequate amounts of dietary 1716-1731. n 2002, the Institute of Medicine fiber from a variety of plant foods. Pop- published a new set of definitions ulations that consume more dietary fi- Ifor dietary fiber (1). The new defi- ber have less chronic disease. In addi- nition suggested that the term dietary tion, intake of dietary fiber has This American Dietetic Associa- fiber would describe the nondigestible beneficial effects on risk factors for de- tion (ADA) position paper uses carbohydrates and lignin that are in- veloping several chronic diseases. Di- ADA’s Evidence Analysis Process trinsic and intact in plants, whereas etary Reference Intakes recommend and information from ADA’s Evi- functional fiber consists of the iso- consumption of 14 g dietary fiber per dence Analysis Library. The use of lated nondigestible carbohydrates 1,000 kcal, or 25 g for adult women and an evidence-based approach pro- that have beneficial physiological ef- 38 g for adult men, based on epidemio- vides important added benefits to fects in human beings. Total fiber logic studies showing protection earlier review methods. The major would then be the sum of dietary fiber against cardiovascular disease. Appro- advantage of the approach is the and functional fiber. Nondigestible priate kinds and amounts of dietary fi- more rigorous standardization of means not digested and absorbed in ber for children, the critically ill, and review criteria, which minimizes the human small intestine. Fibers the very old are unknown. The Dietary the likelihood of reviewer bias and can be fermented in the large intes- Reference Intakes for fiber are based on increases the ease with which dis- tine or can pass through the digestive recommended energy intake, not clini- parate articles may be compared. tract unfermented. There is no bio- For a detailed description of the cal fiber studies. Usual intake of di- chemical assay that reflects dietary methods used in this position paper, etary fiber in the United States is only fiber or functional fiber nutritional access ADA’s Evidence Analysis Pro- 15 g/day. Although solubility of fiber status (eg, blood fiber levels cannot be cess (www.adaevidencelibrary.com/ was thought to determine physiological measured because fiber is not ab- category.cfm?cidϭ7&catϭ0). effect, more recent studies suggest sorbed). No data are available to de- Conclusion Statements are as- other properties of fiber, perhaps fer- termine an Estimated Average Re- signed a grade by an expert work mentability or viscosity are important quirement and thus calculate a parameters. High-fiber diets provide group based on the systematic anal- ysis and evaluation of the support- Recommended Dietary Allowance for bulk, are more satiating, and have been total fiber, so an Adequate Intake (AI) linked to lower body weights. Evidence ing research evidence: Grade IϭGood, Grade IIϭFair, Grade IIIϭ Limited, was instead developed. The AI for fi- that fiber decreases cancer is mixed ber is based on the median fiber in- and further research is needed. Grade IVϭExpert Opinion only, and Grade VϭGrade is not assignable take level observed to achieve the Healthy children and adults can lowest risk of coronary heart disease achieve adequate dietary fiber intakes (because there is no evidence to sup- port or refute the conclusion). Evi- (CHD). A Tolerable Upper Intake by increasing variety in daily food pat- Level was not set for dietary fiber or terns. Dietary messages to increase dence-based information for this functional fiber. consumption of high-fiber foods such as and other topics can be found at the Dietary fiber is part of a plant ma- whole grains, legumes, fruits, and veg- Evidence Analysis Library (www. trix which is largely intact. Nondi- etables should be broadly supported by adaevidencelibrary.com) and sub- gestible plant carbohydrates in foods food and nutrition professionals. Con- scriptions for non-ADA members are usually a mixture of polysaccha- sumers are also turning to fiber supple- can be purchased at the Evidence rides that are integral components of ments and bulk laxatives as additional Analysis Library’s on-line store the plant cell wall or intercellular fiber sources. Few fiber supplements (www.adaevidencelibrary.com/ have been studied for physiological ef- store.cfm). structure. This definition recognizes fectiveness, so the best advice is to con- that the three-dimensional plant ma- sume fiber in foods. Look for physiolog- trix is responsible for some of the physicochemical properties attrib- uted to dietary fiber and that dietary POSITION STATEMENT fiber contains other nutrients nor- 0002-8223/08/10810-0015$34.00/0 It is the position of The American Di- mally found in foods, which are im- doi: 10.1016/j.jada.2008.08.007 etetic Association that the public portant in the potential health ef- 1716 Journal of the AMERICAN DIETETIC ASSOCIATION © 2008 by the American Dietetic Association foods are brought into the diet. Al- Table 1. Dietary Reference Intakes (DRI) for total fibera by life stage group and DRI values though based on limited clinical data, (g/1,000 kcal/d)b a previous fiber recommendation for Adequate Intakec children older than 2 years is to in- Life stage group Men g/1,000 kcal/d Women g/1,000 kcal/d crease dietary fiber intake to an amount equal to or greater than their 0-6 mo NDd ND ND ND age plus 5 g/day and to achieve in- 7-12 mo ND ND ND ND takes of 25 to 35 g/day after age 20 1-3 y 14 19 14 19 years (2). 4-8 y 14 25 14 25 Little clinical data are available for 9-13 y 14 31 14 26 fiber needs in the elderly. Thus, the 14-18 y 14 38 14 26 fiber AI for older adults is also based 19-30 y 14 38 14 25 on 14 g/1,000 kcal. As older adults 31-50 y 14 38 14 25 require less dietary energy than 51-70 y 14 30 14 21 young adults, the AI for fiber con- Ͼ70 y 14 30 14 21 sumption in older adults decreases. Pregnancy All fiber recommendations need to Ͻ18 y NAe NA 14 29 recognize the importance of adequate 19-50 y NA NA 14 28 fluid intake, and caution should be Lactation used when recommending fiber to Ͻ18 y NA NA 14 29 those with gastrointestinal diseases, 19-50 y NA NA 14 29 including constipation. The 2005 US Dietary Guidelines aTotal fiber is the combination of dietary fiber (the edible, nondigestible carbohydrate and lignin components in plant foods) and functional fiber (isolated, extracted, or synthetic fiber that has proven health benefits). recommend high-fiber food such as bValues are example of the total grams per day of total fiber calculated from g/1,000 kcal multiplied by the median whole grains and vegetables and energy intake (kcal/1,000 kcal/day) from the Continuing Survey of Food Intakes by Individuals 1994-1996, 1998. fruits, and fiber intake levels of 14 cIf sufficient scientific evidence is not available to establish an Estimated Average Requirement, and thus calculate a g/1,000 kcal (3). MyPyramid also sup- Recommended Dietary Allowance, an Adequate Intake (AI) is usually developed. For healthy, breastfed infants, the AI is ports this recommendation (4). Nutri- the mean intake. The AI for other life stage and sex groups is believed to cover the needs of all healthy individuals in tion Facts labels use 25 g dietary fiber the group, but a lack of data or uncertainty in the data prevents being able to specify with confidence the percentage of individuals covered by this intake. per day for a 2,000 kcal/day diet or 30 dNDϭnot determined. g/day for a 2,500 kcal/day diet as eNAϭnot applicable. goals for American intake. Dietary fiber intake continues to be less than recommended in the United fects. Cereal brans, which are efits were not used as the basis for the States with usual intakes averaging obtained by grinding, are anatomical AI. only 15 g per day (1). When asked layers of the grain consisting of intact There is no AI for fiber for healthy about their perceptions of their di- cells and substantial amounts of infants aged 0 to 6 months who are etary fiber intake, 73% of individuals starch and protein; they are catego- fed human milk because human milk with a mean fiber intake below 20 g/d rized as dietary fiber sources. does not contain dietary fiber. During think the amount of fiber they con- Dietary Reference Intakes (DRIs) the 7- to 12-month age period, solid sume is “about right” (5). Many pop- for total fiber by life stage group are food intake becomes more significant, ular American foods contain little di- shown in Table 1. The AIs for total and so dietary fiber intake may in- etary fiber. Servings of commonly fiber are based on the intake level crease. However, there are no data on consumed grains, fruits, and vegeta- dietary fiber intake in this age group observed to protect against CHD bles contain only 1 to 3 g dietary fiber and no theoretical reason to establish based on epidemiologic, clinical, and (6)(Table 2). Major sources of dietary an AI. There is also no information to mechanistic data.