What Makes a Good Multivitamin? And Who Needs One?
In a perfect world, patients would get an adequate amount of essential nutrients from a well-balanced diet. However, for a variety of reasons—including nutritional deficiency, pregnancy, advanced years, and lifestyle—many patients simply are unable to meet these recommended standards and may require dietary supplementation.
This handout commences a series devoted to examining appropriate multivitamin use. We begin with an overview of who should take a multivitamin and the components of a good multi-
vitamin. Subsequent handouts will address specific nutrients, their physiological effects and safety profiles, and special needs populations, including children, women, and the elderly.
What Can a Multivitamin Do?
Research has shown that adequate levels of folate can prevent neural tube disorders in the developing fetus. However, demonstrating that multivitamin supplementation prevents chronic disease has been another matter—made difficult by many contributing confounders, such as diet, family history, and environmental issues.
Clinical trials and observational studies suggest an association between multivitamin use and disease prevention, but no clear causal relationship has been shown. For example, among the nearly 90,000 participants in the Harvard Nurses' Health Study, the women who took multi-vitamins for 15 years reduced their risk of colon cancer by as much as 75%.1 The data also suggest that multivitamins may reduce the risk of breast cancer in certain women. Conversely, results from the National Health and Nutrition Examination Survey found cancer mortality and overall mortality were similar in regular users and nonusers of dietary supplements.2
Who Needs to Take a Multivitamin?
How many of your patients take multivitamins? According to a survey conducted by the American Dietetic Association (ADA), nearly half of Americans consume vitamin and mineral supplements on a daily basis.3
A well-balanced diet can provide adequate levels of most vitamins and minerals as well as fiber and phytochemicals. Often, people who eat a nutritious diet don't need to supplement with a multivitamin. Ironically, many studies have shown that people who have higher intakes of nutrients from food are the very people who are most likely to take a multivitamin.2-4
As reflected in the ADA study, regular vitamin and mineral supplementation increases with age and is associated with more frequent intake of fruit and vegetables.3,5 Multivitamin use also seems to be most prevalent among those who believe their health is affected by diet.6
Try as many patients might, however, only 28% of Americans have made significant adjustments in their eating behavior.3 The vast majority have failed to achieve a healthy, nutritious diet or have made no effort at all. In addition, many people have special dietary concerns and may not be able to get adequate levels of nutrients from the food they eat. These people may include the elderly, children, pregnant women, the physically active, and those with absorption problems or chronic illnesses. In these situations, dietary supplementation may be necessary.
What Constitutes a Good Multivitamin?
Currently, the Food and Nutrition Board of the National Academy of Sciences is evaluating and revising the Recommended Daily Allowances (RDAs). New recommendations, called Dietary Reference Intakes (DRIs), have been established for those nutrients that have undergone this review process.
The chart below reflects the most current data available, using RDAs for those nutrients awaiting DRI review. Consumers should select a multivitamin that contains nutrient levels appropriate for their age and gender.
References
1. Giovannucci E, et al. Multivitamin use, folate, and colon cancer in women in the Nurses' Health Study. Ann Intern Med 1998;129:517-524.
2. Koplan JP, et al. Nutrient intake and supplementation in the United States (NHANES II). Am J Public Health 1986;76:
287-289.
3. The American Dietetic Association. Americans' food and nutrition attitudes and behaviors—American Dietetic Association's Nutrition and You: Trends 2000. Chicago, IL: 2000. Available at: http://www.eatright.org/pr/2000/010300a.html. Accessed October 19, 2000.
4. Kim I, et al. Vitamin and mineral supplement use and mortality in a U.S. cohort. Am J Public Health 1993; 83:546-550.
5. Frank E, et al. Use of vitamin-mineral supplements by female physicians in the United States. Am J Clin Nutr 2000;72:
969-975.
6. Subar AF, Block G. Use of vitamin and mineral supplements: Demographics and the amounts of nutrients consumed; the 1987 Health Interview Study. Am J Epidemiol 1990;132:1091-1101.
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