Dangers associated with dietary supplements

Numbers can deceive and may tell only part of the story. On the other hand, numbers can also get at the crux of the matter in a more rigorous and comprehensive fashion than anecdotal stories. One goal of this website is to emphasize the key numbers behind medical topics.

The following is an anecdotal story in the New York Times from an article on dietary supplements:

"Christopher, a high school student from Katy, Tex., suffered severe liver damage after using a concentrated green tea extract he bought at a nutrition store as a “fat burning” supplement. The damage was so extensive that he was put on the waiting list for a liver transplant."

This is a scary story. What do the numbers say?

Approximately 20% of drug-related liver damage cases may be the result of taking diet supplements, an increase from 7% a decade ago reflecting the growing popularity of supplements. Experts say that this figure may actually underestimate the true number.

These numbers sound alarming but they need to be placed in the proper context. There are approximately 2000 cases of acute liver failure each year in the U.S., and about 50% are drug-related (Tylenol accounts for about 40% of these). The liver is the organ involved in detoxifying foreign substances like drugs. Thus, there are about 200 cases of drug-related liver failure each year caused by dietary supplements.

On the one hand, 200 is not a big number compared to the 100 million or so adult Americans who take supplements, which represents about half of all adults in the U.S.

"Americans spend an estimated $32 billion on dietary supplements every year, attracted by unproven claims that various pills and powders will help them lose weight, build muscle and fight off everything from colds to chronic illnesses. About half of Americans use dietary supplements, and most of them take more than one product at a time."

On the other hand, liver failure is a very serious (life-threatening) condition, and in most cases, it requires a liver transplant, which is an expensive and dangerous operation. The five-year survival rate for a liver transplant is 80%, and there is a lengthy waiting list for donated livers (depending on the person). From this perspective, 200 is a large number of people to have such a serious medical condition.

A key takeaway message is that dietary supplements are not regulated by the Food and Drug Administration (FDA) in the say way that the FDA regulates medical drugs. In 1994, Congress passed the Dietary Supplement Health and Education Act of 1994 which stated that "The manufacturer of a dietary supplement or dietary ingredient is responsible for ensuring that the product is safe before it is marketed," and that the "FDA is responsible for taking action against any unsafe dietary supplement product after it reaches the market."  In other words, the manufacturer of the supplement is responsible for its safety, and the FDA can act only after reports of adverse reactions. With respect to conventional drugs, the FDA ensures the effectiveness and safety of the drug through clinical trials before the drug is used on the general patient population.

As a doctor quoted in the New York Times article stated:

“It’s really the Wild West,” said Dr. Herbert L. Bonkovsky, the director of the liver, digestive and metabolic disorders laboratory at Carolinas HealthCare System in Charlotte, N.C. “When people buy these dietary supplements, it’s anybody’s guess as to what they’re getting.”

So be careful when you take a dietary supplement.

Figure 1. Dietary supplements are not regulated by the FDA for either efficacy or safety.