The Regulation of Dietary Supplements
One hundred years ago, the dietary supplement industry was very different from today. Production and processing were not standardized, sanitation was questionable (manufacturers had little understanding of bacterial/microbial control and refrigeration was primitive), and distribution was unregulated. The twentieth century brought many changes in how dietary supplements were handled and transported, and several laws sought to improve supplement manufacturing practices.
The U.S. government has long concerned itself with regulation of the substances Americans consume. In the early 1900s, what we now consider to be dietary supplements were regulated as foods. While they are still technically considered foods today, dietary supplements are now regulated by the Dietary Supplement Health and Education Act (DSHEA) under the FDA.
Do Dietary Supplements Provide a Benefit?
While characteristics such as age and geographic location are related to dietary supplement use, the most striking characteristic about dietary supplement users is that they make health and nutrition a top priority. Therefore, it is important to consider whether people who take dietary supplements benefit from them and whether those people who might benefit from dietary supplements take them.
To consider these questions, I created two diets for a hypothetical 50-year-old woman who is 5 feet 6 inches tall, weighs 150 pounds (body mass index of 24.2; a body mass index of 25 is overweight and 30 is obese), is moderately active, and has a daily energy expenditure of approximately 2110 calories. Diets 1 and 2 are similar from the standpoint of total calories, and both diets comprise one snack and three meals, including dinner at a restaurant. Although I do not recommend evaluating a person’s nutrient intake based on one day’s diet (and people who occasionally consume poor-quality diets may compensate with variety over time), I am doing this for the purpose of illustration.
Both diets are compared with regard to the percent daily value (%DV) and the tolerable upper limit (UL). The %DV is calculated using the nutrient per serving of food compared with the reference daily intake for that nutrient established by the Food and Drug Administration.
The UL is the highest level of a nutrient consumed in one day that is likely to pose no risk of adverse effects. Whether intake of vitamins and minerals above 100 percent of the %DV provides additional benefit is questionable, but exceeding the UL may cause harm. There are no equivalent levels set for other substances such as those found in herbal and botanical dietary supplements. Due to inadequate research and scientific consensus, I cannot comment on their contribution to these diets.
Both diets 1 and 2 meet or exceed established goals for calories, protein, and fat, and both are low in calcium. Diet 1 is low in many nutrients, including fat-soluble vitamins (vitamins A, E, K, and likely D); the B vitamins (thiamine, riboflavin, folate, and vitamins B6 and B12); several antioxidants (vitamin C and selenium); and minerals (potassium, iron, magnesium, zinc, and copper). A person consuming this diet would therefore be a good candidate for daily supplementation with a multivitamin and/or specialized supplements such as calcium with vitamin D, B-complex vitamins, and antioxidants. However, a person who relies heavily on convenience and prepared foods (as in diet 1) is less oriented to healthful eating and may therefore be less likely to consume these supplements.
Diet 2 exceeds nutrient recommendations for vitamins A, C, and K, the B vitamins, iron, magnesium, zinc, and selenium, and consumption of several nutrients is above the UL. Most worrisome is vitamin A, a fat-soluble vitamin that is stored in the body rather than excreted when consumed in excess, which may be associated with adverse effects. If an individual consuming this diet were to take a dietary supplement (for example, multivitamin or single-nutrient supplements), other nutrient levels could easily exceed potentially harmful levels. A person consuming diet 2, which is composed of whole grains (some fortified), colorful fruits and vegetables, and sources of mono- and polyunsaturated fats (nuts, olive oil, and salmon), makes healthful food choices and is therefore more likely to use dietary supplements.
Many people who take dietary supplements are not lacking nutrients, according to U.S. government recommendations, and little scientific evidence suggests that consuming more than the recommended amounts of some nutrients improves health.
Taking dietary supplements to fill a dietary gap, however, is beneficial. Several populations may need dietary supplementation to meet their nutrient goals. The elderly, who require fewer calories as they age, still need to consume high levels of nutrients. One Boston study found that many elderly people did not meet their nutrient needs from diet alone, and a study of the older-old in Georgia found that dietary supplement users and nonusers did not get enough of some nutrients from diet alone. Recent data also suggest that most Americans, especially women and teenage girls, are not consuming adequate amounts of vitamin D.
Experts say a varied, healthful diet is the best way to meet nutritional needs, and consumption of dietary supplements cannot make up for a poor diet. When taken by people who need them, however, dietary supplements can improve nutritional status.