Liver injury due to herbal and dietary supplements

The use of Herbal and Dietary Supplement (HDS) use in the U.S. is suspected to be on the rise. This assertion stems from several epidemiological studies as well as data reflecting supplement sales. Concurrent with this rise in use is an increasing awareness of liver injury resulting from HDS. The literature is rife with case reports of hepatotoxicity attributed to various single or multi-ingredient products.

The U.S. Drug Induced Liver Injury Network (DILIN) was funded by the National Institutes of Health starting in 2003 to better understand the causes of liver injury from drugs and HDS. Although the DILIN is not population-based, there are centers in many major metropolitan areas around the country, thus giving a reasonably good sampling of the population. The DILIN's early findings indicated that HDS are the second most common types of agents to cause liver injury, after antimicrobials. In the DILIN's most recent publication of its experience with liver injury from HDS, products used for the purposes of bodybuilding and muscle enhancement are the most common types of supplements implicated in liver injury. The injury resulting from those products is characteristic, with prolonged jaundice and pruritus being typical. On the other hand, injury resulting from non-bodybuilding products, such as those used for weight loss among other reasons, tends to be of a different pattern and more commonly associated with the need for liver transplantation than even injury resulting from prescription medications.

Many challenges face those who aim to better understand the hepatotoxicity that results from some HDS. First, supplements tend to be complex mixtures that can vary in their composition over time and from batch to batch. Moreover, some products may contain undeclared ingredients or contaminants. These factors confound the quest to find the culprit ingredient. Second, it is unclear if consumers' behavior may predispose them to injury. These behaviors may include the conditions under which they are used, such as extreme fasting, and the amount used. The combination of various products or concomitant use of conventional medications may also affect toxicity profile. Third, host factors and genetics may play a role in hepatotoxicity as is the case for some medications. Finally, the current direction of research must inform regulation that will give the public greater assurance of safety.