The answer is yes, according to a presentation at the annual meeting of the American Association for the Study of Liver Diseases. Dr. Victor Navarro said at a press briefing that “herbal supplements are a common cause of liver injury.” He went on to say that “there are lots of products that are difficult to identify what they and what they’re used for.”

In a study of drug-induced liver injuries, it was found that 20% were caused by dietary supplements. Many of these products were sold as bodybuilding supplements or weight-loss supplements. There are two ways in which the products can be dangerous: they may include ingredients that are not listed on their labels, or they may be adulterated with additives on purpose (to support for purpose for which it is being marketed, such as for sexual enhancement).

In the study, people with drug-induced liver damage had used over 300 different dietary supplements. Chemical analysis of these products found some with hepatotoxins such as anabolic steroids or other pharmaceuticals, although the labels did not so indicate. One problem with using such “natural” or “herbal” products is that it is assumed there is nothing harmful in them. “Natural” in most people’s minds equates with “harmless.” But, unlike drugs, these supplements are not regulated or approved by the FDA. The companies that make these products often fail to list all of the ingredients or fail to test for toxicities or other problems that can arise from their use.

Physicians studying the causal relationship between the products and liver injuries found that identifying the problem often led to the product no longer being sold, but they are then replaced with a different product or at least one with changed labels. One positive outcome of the studies, according to Dr. Norah Turreault of the University of California San Francisco, is that “it highlights the fact that these herbal products contain ingredients that are unknown to the patients taking them.” The message to consumers is “don’t assume that a ‘natural’ or ‘herbal’ product can only help you — it can also cause serious damage.”