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Despite efforts, limited efficacy exists for dietary supplements
Supplement-drug interactions and supplement side effects are an issue.
It is estimated that more than 100 million Americans regularly consume dietary supplements, including vitamins, minerals or herbs, at an annual cost of more than $20 billion.
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Dietary supplement users tend to be older, women, white, affluent and educated. A 2006 survey of AARP members revealed that of respondents who admitted taking dietary supplements and seeing a physician, only 22% indicated that they discussed supplement use with their physician. Of those who did not discuss their supplement use, 42% indicated that the doctor never asked, 30% indicated that they didn’t know they should, 19% felt that there was not enough time during the office visit, 17% didn’t think that the doctor knew the topic and 12% were afraid that the doctor would have been dismissive or told them not to take the supplements.
With such widespread and usually undisclosed use, understanding the evidence related to product content, efficacy and safety is important.
Lately, many U.S. consumer goods, including toys, pet food, toothpaste and most recently drugs, have been plagued with recalls due to hazardous ingredients. Dietary supplements are regulated by the FDA as a food, not a drug. Therefore, unlike drugs, there is no required oversight of the product ingredients or manufacturing processes.
In 2001, the United States Pharmacopeia (USP), a nongovernmental, nonprofit organization, launched a verification program for dietary supplements. Although this program is not mandatory, there are some companies that utilize this program, meaning their products have been rigorously tested and meet the USP standards for integrity (the product contains the ingredients in the specified amount listed on the label), and for purity. Importantly, this verification program also certifies that the product will be broken down appropriately by the body for adequate absorption and that the factory created the product utilizing good manufacturing processes. These products will have the “USP verified dietary supplement” seal displayed on the product label. Products bearing the USP verified mark have been available since the beginning of 2003 and can be found in most major drug, food, and discount retailer stores and selected health food stores. There are nine companies participating in the USP product verification program according to the USP website: Berkley & Jensen, TruNature, Kirkland Signature, Q-Gel, Equaline, Nature Made, NutriPlus, YourLife and Sunmark.
Although USP-verified products may be pricier than store brands, patients who insist on taking dietary supplements should be encouraged to purchase products that have undergone content verification under the USP verification program.
The USP verification program does not certify product efficacy or test product safety. Dietary supplement products are allowed to include claims on the label related to health; nutrient content (ie, “fortified, high, rich in, excellent source of, good source of, and high potency”); and structure-function (ie, “calcium builds strong bones”). However, the label must also contain the disclaimer, “This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.”
More than a decade ago, the National Institutes of Health created the Office of Dietary Supplements as part of a congressional law. Since then, this NIH office has spent more than $113 million to fulfill its mission “to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results and educating the public to foster an enhanced quality of life and health for the U.S. population.”
Despite the creation of this NIH office and its considerable budget over the last decade, there are only limited efficacy data supporting routine use of dietary supplements, and perhaps more importantly, there are supplement-drug interactions and supplement side effects that should limit its use in some patient populations, particularly those with cardiovascular disease.
Rhonda Cooper-DeHoff, PharmD, is a Research Assistant Professor at the University of Florida College of Medicine in Gainesville.