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General Multivitamin-Mineral Supplements

July 5th, 2005

Should dietetics professionals advise general multivitamin-mineral supplements at modest doses to help meet dietary recommendations? As already indicated, a variety of good foods wisely selected is the basis of a nutritious diet, will meet dietary recommendations for most nutrients, and is the best way to assure a balance of nutrients and healthy food components for which no recommendations have been established. While there is little scientific evidence of benefit to the average person, there is also little evidence of harm from low-dose multivitamin or multivitamin-mineral supplements in amounts that do not exceed 100% of the RDA. The choice of either a multivitamin or highly fortified foods (such as some breakfast cereals) can be used to meet the new recommendations to increase synthetic sources of folic acid for women capable of becoming pregnant and synthetic sources of vitamin B-12 for older adults. Otherwise, recommendations for these groups can be met by using specific supplements providing folic acid or vitamin B-12, respectively.

Low-dose multivitamin-mineral supplements may provide benefit to those with limited dietary intakes. Such low-dose supplements improved indices of immune function and reduced infectious illness in a double-blind placebo-controlled investigation of 96 free-living Canadian elderly men and women. Similar supplements had no benefit in a double-blind placebo-controlled study of muscle weakness and physical frailty of 100 very elderly people in a Boston nursing home. More research in this area should be encouraged.

Professional recommendations to use low-dose multivitamin and mineral supplements should depend on individualized dietary assessments that consider how usual diets can be modified with food, fortification or supplemental sources of nutrients to meet individual needs. People using both highly fortified foods and multivitamins, even without other specific nutrient supplements can easily consume 300% of the RDA for many known nutrients. Some would question whether these high intakes of known nutrients are appropriately balanced with other health promoting components of food, many of which are unidentified. The goal should be to meet the RDA or AI while not exceeding the UL. As indicated by the Food and Nutrition Board, “there is no established benefit for healthy individuals if they consume a nutrient in amounts above the recommended intake (RDA or AI)”.

There is a special need for moderation under certain circumstances. For example, preformed vitamin A should not be taken in the first trimester of pregnancy. For men and postmenopausal women, who generally have adequate iron stores, supplemental iron, without a clinical assessment demonstrating low iron status, has little likelihood of benefit and may be of risk to those with certain genetic characteristics (see section on Toxicities, adverse nutrient interactions, and safety, p.x). In addition to evaluating total intakes for meeting and not greatly exceeding the Recommended Dietary Allowances, dietetics professionals should use the new UL designated by the Food and Nutrition Board to avoid dangerously excessive intakes.

Entry Filed under: Vitamins & Minerals

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