The latest recommendations from the Food and Nutrition Board, for the first time, include recommendations that supplements or fortified foods be used to obtain desirable amounts of some nutrients. Research demonstrated that the risk of bearing children with neural tube defects was reduced by folic acid supplementation. This and related research led to the recommendation that women capable of becoming pregnant obtain 400µg of synthetic folic acid daily from either fortified foods or a supplement in addition to consuming food folate from a varied diet (1). It is not known whether lower amounts of synthetic folic acid, or an equivalent amount of folic acid from food would provide a similar protective effect. However, it is known that food folate is not as well absorbed as synthetic folic acid and that to assess folate intake, adjustments must be made for bioavailability. Further research should help clarify this question.
Atrophic gastritis is a condition that reduces the absorption of food-bound vitamin B-12. Because 10–30% of persons older than 50 years have atrophic gastritis, the recommendation for this age group is to obtain vitamin B-12 from supplements or fortified foods.
The new recommendations for calcium, 1300mg for 9–18 year olds, 1000mg for 19–50 year olds, and 1200mg for adults greater than 51 years of age, are considerably greater than previous recommendations (800mg for adults) and average US calcium intakes (approximately 700-800mg). Because there was not adequate research data available to determine an EAR or RDA for calcium, the new calcium recommendations are listed as Adequate Intakes. Although such recommendations can be met with generous consumption of (low fat) dairy products, some people may prefer to meet the recommendations with fortification or supplemental sources of calcium.
Meeting the new AI for vitamin D will likely require supplemental sources of vitamin D for the elderly if they do not drink generous quantities of fortified milk. Individualized dietary assessment and counseling can help identify those who are able to obtain recommended levels of calcium and vitamin D from dietary (and sunlight) sources, and those who may benefit from fortified foods or supplements.
When dietary selection is limited, nutrient supplementation can be useful to meet dietary recommendations. Examples include supplemental vitamin B-12 for strict vegans who eliminate all animal products from the diet; vitamin D for those with limited milk intake and sunlight exposure; calcium supplements and/or calcium fortified foods for those with lactose intolerance or allergies to dairy products; and a multivitamin and mineral supplement for those following severely restricted weight-loss diets (eg, <1200kcal/day).
Iron supplementation during pregnancy is routinely practiced in the United States. Two expert committees have called for more research concerning whether iron supplementation should occur routinely or only on the basis of individual iron status assessment. A Food and Nutrition Board committee recommended further study into the possibility of adverse outcomes at very low or high hemoglobin levels, but concluded that the practice of routine iron supplementation should not be changed without further research, a conclusion confirmed by a more recent expert group.
In many areas the research evidence remains equivocal or incomplete. However, recent recommendations from the Food and Nutrition Board provide a useful indication of unbiased, well-considered scientific judgements from nutrition experts. This current evaluation of the available scientific research does not support the efficacy of supplement doses greater than the RDA for such nutrients as vitamin C, vitamin E, or selenium that are commonly marketed for the prevention of chronic disorders such as heart disease or cancer. Randomized, placebo-controlled trials with vitamin E supplementation have not provided evidence of harm, but neither have they provided consistent evidence of effectiveness in prevention of cancer or cardiovascular disease. As new research becomes available, recommendations must be based on a careful consideration of the total scientific literature.
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