Saturday, April 12, 2008

Trusting Dietary Supplements, Part 2

The government does not regulate supplements to the extent that it regulates prescription drugs. Supplements in the US are regulated as foods, not as drugs. That means a supplement manufacturer:
  • Does not have to prove a supplement is safe (drug manufacturers do).
  • Does not have to prove a supplement works (drug manufacturers must prove efficacy).
  • Does not have to prove the quality of a supplement (does not have to prove that the content matches that declared on the label).
The FDA does not analyze dietary supplements before they are sold to customers. Who, then, is responsible for the safety, efficacy, and quality of a supplement? The manufacturer. And manufacturers make mistakes:

Echinacea and Truth in Labeling, Archives of Internal Medicine, 2003

In this study, 59 single-herb preparations of Echinacea were analyzed:
  • 6 (10%) contained no measurable Echinacea.
  • Only 31 (52%) contained what was listed on the label.
  • 12 (20%) had no expiration date.
  • Only 4 (7%) met all 4 of the FDA's labeling requirements. 1
  • And when it came to the word "standardized":
    "Claims of standardization by the manufacturer did not indicate that the preparation reliably contained the labeled amount or even the labeled species."
Not only are consumers left to trust that what the label says is in the bottle really is in the bottle, so are researchers. Investigators in clinical trials typically do not conduct independent analysis of the supplements used. Is it any wonder then why supplement trials report conflicting results - even with the best research protocol?

The US Pharmacopeia invites supplement manufacturers to voluntarily comply with testing of samples and to participate in postmarketing product surveillance in return for certification. (See here for some companies that participate.) In the above study, USP weight standards for Echinacea were used by 5 (8%) of the samples. However, "none of those products had content consistent with their labeling."
1 Those would be: 1. Dietary Supplement Statement (suggested dose). 2. Supplement Facts Box. 3. Nutrition Facts. 4. FDA Disclaimer, e.g. "This [claim] has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent disease."

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