Calcium Citrate in Fortified-Food Applications By Gerhard Gerstner, Ph.D. Contributing Editor alcium is a key mineral in the human body, necessary for the normal growth and C development of the skele- ton as well as for teeth, nerve, muscle and enzyme functions. As the body’s calcium absorption capabilities reduce with age, it is vital for older individuals to have a suffi- cient calcium intake. Calcium require- ments vary throughout an individual’s life and for different population groups. However, it is generally evident that a significant proportion of the population in Western countries fails to achieve the recommended calcium intakes. Poor dietary habits are seen to be responsible for this situation, especially when fast- food consumption dominates much of the population’s menu. Various studies, including “The Min- eral Fortification of Foods,” published in 1999 by Leatherhead International in its anhydrous form, as well as cal- Optimal Daily Calcium Intake cium lactate gluconate. Tricalcium citrate (TCC), com- According to NIH Recommendations monly referred to as calcium citrate, is a high-quality calcium source for Calcium (mg/day) food fortification. Its main character- istics are good solubility at low pH, a Infants, up to six months . .400 neutral taste and flavor profile, high Infants, six to 12 months . .600 calcium content and excellent bio- availability. Besides the standard pow- Infants, one to 10 years . .800 der product, TCC is also supplied as Children and young adults, 11 to 24 years . .1,200 to 1,500 a micronized (ultra-fine) granulation Adults, 25 to 65 years . .1,000 that will dissolve even more quickly in acidic applications. Adults, older than 65 years . .1,500 Pregnant and lactating woman . .1,200 to 1,500 Application selection The selection of the appropriate salt for a specific application is usu- ally based on the consideration of a number of properties associated with Ltd., Surrey, UK, showed that a sig- There are several options to avoid the respective product, such as solu- nificant proportion of the population calcium deficiency by increasing the bility, taste, calcium content and bio- groups failed to achieve the calcium daily calcium intake: A balanced diet availability. Economic considerations intakes in Western countries. This with calcium-rich foods, such as milk, are another important factor to review observation is thought to be one of the dairy products and certain vegetables before making a decision. leading factors causing osteoporosis, (broccoli, Chinese cabbage, legumes), Solubility. There are calcium salts and was noted in a 1991 article from would be the best solution. However, with a rather good solubility, includ- the American Journal of Clinical this would require a profound change ing calcium gluconate and calcium Nutrition titled “Calcium Metabolism in dietary habits of Western society. lactate, but their drawback is a low and Calcium Requirements During Another possibility would be con- calcium content. Calcium salts with Skeletal Modeling and Consolidation.” suming food products fortified with high calcium content, on the other hand, As a consequence, national authorities calcium. The third option is the intake are poorly soluble. TCC offers a good all over the world recently have re- of calcium-supplement products. combination: It shows a high calcium considered recommendations in order level and moderate solubility. Solu- to take remedial measures against cal- Common calcium sources bility is strongly influenced by the pH cium deficiency and, accordingly, to There are different calcium sources of the system, since the solubility of reduce the risk of osteoporosis. In this commercially available for use in food calcium salts typically increases with respect, the United States National and dietary supplements: decreasing pH. TCC shows improved Institutes of Health (NIH) has increased • inorganic salts such as calcium solubility at pH values below 4.5, as the amounts of optimal daily calcium carbonate and calcium phosphate; and found in orange juice. intake and defined specific values for • organic salts such as calcium cit- And contrary to other salts, TCC is each population group. For example, rate, calcium lactate, calcium lactate more soluble at low temperatures, which calcium intake should be 1,000 mg/day gluconate and calcium gluconate. can be an advantage for cold food pro- for adults (25 to 65 years of age) and as Other forms of calcium common- cessing. To further increase the solu- much as 1,500 mg/day for seniors (older ly supplied for fortification and sup- bility and ease of dispersion, companies than 65 years) or lactating women. plementation are calcium gluconate such as Jungbunzlauer have developed several types of particularly fine (micronized) TCC grades. Important Characteristics of Common Calcium However, the high solubility of cal- Sources Used in the Food Industry cium salts, such as calcium lactate or calcium gluconate, can also lead to adverse effects. Due to the fact that Product Solubility Taste Calcium with high-soluble salts, more free cal- Content cium ions are in solution and available for reaction than with TCC, complica- Calcium carbonate Very low Soapy, lemony 40% tions in the form of calcium sediments Calcium phosphate Very low Sandy, bland 17% to 38% can develop with time. This is the case if components (e.g. free protein, tar- Calcium citrate (TCC) Moderate Tart, clean 21% trate or phosphate) that give insolu- ble salts with calcium are present in Calcium lactate Good Neutral 13% the product. Thus, although it is pos- Calcium lactate gluconate Very good Neutral 10% to 13% sible to add more calcium lactate than TCC to beverages, higher amounts of Calcium gluconate Good Mild, neutral 9% calcium in the product might be dif- ficult to achieve without control of pH and addition of chelating agents, such as potassium citrate. Taste and mouthfeel. Generally, ic salts, but their application in foods Research Council’s “Recommended high levels of calcium, particularly and beverages remains limited due to Dietary Allowances: 10th edition. A insoluble forms such as carbonates their poor solubility and their influ- Report of the Subcommittee on the and phosphates, tend to produce a ence on taste in the final application. Tenth Edition of the RDA.” Several chalky mouthfeel and may promote However, organic calcium salts remain different factors influence this level, astringency or bitter taste in the fin- an option, with TCC showing by far including which type of salt provides ished product. Calcium lactate may the highest calcium content (21%), the calcium. impart some bitter notes at high con- compared to calcium lactate (13%), Various scientific studies have shown centrations. Calcium carbonate comes calcium lactate gluconate (10% to 13%) that organic calcium salts outperform across as soapy or lemony and has the and calcium gluconate (9%). inorganic calcium sources, such as disadvantage of developing CO2 in Economic considerations. Among calcium carbonate and calcium phos- the stomach. Calcium phosphate has a the organic salts with better solubility phate, with regard to their relative bio- bland flavor, but imparts a gritty mouth- and more neutral taste profiles, TCC availability. Accordingly, the United feel. TCC, calcium lactate gluconate clearly stands out as the most eco- States National Institutes of Health and calcium gluconate are considered nomic option for calcium addition, has recommended calcium citrate for to be the most neutral calcium salts. especially when the price per gram of supplementation, especially for older Since the particle size and solubil- calcium added is calculated for the individuals where absorbability can ity are linked with mouthfeel properties, product to be fortified. be a limiting factor due to reduced companies have developed micronized Bioavailability. Any nutrient’s effec- gastric-acid production. Recently, re- grades that provide a neutral taste pro- tiveness depends on its bioavailability, searchers at the University of Texas, file in final applications with excellent which means how well the human Austin, conducted a meta-analysis of dispersion characteristics. body absorbs and utilizes it. On aver- calcium bioavailability, which evalu- Calcium content. Inorganic salts, age, only about 10% to 30% of calci- ated studies on the bioavailability of such as carbonates and phosphates, um is absorbed from a mixed diet by two of the most common forms of cal- contain more calcium than the organ- healthy adults, according to the National cium supplements, TCC and calcium carbonate. Over 90% of the studies re- salts in plain water. It is concluded that the absorption on nutritional minerals viewed showed greater absorption of these differences have no effect on whereas alternative calcium sources calcium from TCC than calcium car- absorbability in acidic environments significantly interfered with iron. bonate by an average of 22% to 27%. such as the gastric acid in the human The use of TCC is particularly rec- Similarly, calcium phosphate also stomach. Studies with healthy male ommended for acidic applications, such has been shown in scientific studies to volunteers revealed that, compared to as juices and fruit preparations, but display lower bioavailability than TCC. calcium lactogluconate/carbonate and also in various dairy products, such Furthermore, it is not considered to be an calcium phosphate, oral administration as yogurt and cheese. Due to its out- appropriate ingredient for calcium forti- of TCC induced