Dietary Supplements

Posted by Janine Wong MS, RD on November 6, 2012

The Starting Line: 

Which dietary supplements are safe and effective?


A dietary supplement is any product designed to increase a specific component of the diet, including vitamins, minerals, herbs, botanicals, and amino acids. Many substances can be sold over the counter as dietary supplements, even steroids. A recent study by Tscholl, et al concluded that the incidence of supplement use among athletes is high - up to 66% in track and field athletes. Experts from the Academy of Nutrition and Dietetics (formerly the American Dietetic Association), American College of Sports Medicine, and Dietitians of Canada do not recommend routine dietary supplementation for athletes except to correct a vitamin or mineral deficiency.

Unlike drugs, dietary supplements do not have to be proven safe or effective before being sold. A popular example is ephedrine (or ephedra alkaloids) - marketed for weight loss, increased energy, and improved athletic performance. In an FDA funded review by Haller, et al, ephedra alkaloids were found to lead to numerous adverse effects including high blood pressure, heart palpitations, increased heart rate, arrhythmias, heart attack, stroke, transient ischemic attack (mini-stroke), seizure, and sudden death. In 140 cases reviewed, 10 resulted in death, and 13 led to permanent disability. The vast majority of dietary supplements have not undergone this degree of scrutiny, which is usually only triggered by sentinel events such as death and disability. While ephedrine and ephedra alkaloids are not approved as drugs, they are still marketed as dietary supplements, often under botanical names to disguise the ingredient.

When choosing a dietary supplement, your doctor or registered dietitian can help determine if it is actually beneficial to you. Reading supplement labels carefully is not enough to determine if a supplement is safe and effective. Testing of off-the-shelf products by Gurley, et al, has shown over 20% discrepancy between the amount of substance in the product and what is stated on the label, in over half of brands tested. U.S. Pharmacopeia, the National Sanitation Foundation, and are some independent organizations that evaluate the purity of dietary supplements. in particular evaluates for the presence of substances banned in competition. Look for these seals on the label:

Determining the efficacy of a dietary supplement is a much more complicated issue that is usually left to independent researchers. For example, a recent review of peer reviewed studies by Ciocca concluded that supplements containing testosterone precursors or nitric oxide enhancers have failed to show increased muscle mass. To view a synopsis of the research done on individual supplements, visit these websites:

Office of Dietary Supplements, National Institutes of Health

Medline Plus


The Finish Line:

Vitamin and mineral supplements can help complement your diet if you are at risk for deficiency. Be cautious about choosing a supplement by checking up on the safety and effectiveness.  



1. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the American Dietetic Association. March 2009. 109(3);509-527.

2. Ciocca, M. Medication and Supplement Use by Athletes. 2005. Clin Sports Med, 24:719-738.

3. Gurley, B.J., Gardner, S.F., Hubbard, M.A. Content versus label claims in ephedra-containing dietary supplements. Am J Health Syst Pharm 2000;57:963-9.

4. Haller, C.A., Benowitz, N.L. Adverse Cardiovascular and Central Nervous System Events Associated with Dietary Supplements Containing Ephedra Alkaloids. New England Journal of Medicine. 2000. 343:1833-1838.

5. Tscholl, P., Alonso, J.M., Dollé, G., Junge, A., Dvorak, J. The Use of Drugs and Nutritional Supplements in Top-level Track and Field Athletes. American Journal of Sports Medicine. 2010, 38(1):133-140.

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 *Note: This general information is not intended to be a substitute for medical treatment or advice. Always consult a professional before making changes to your health and wellness practices. 

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