Weight-loss supplements, as well as various body-building products, have recently been linked to liver damage. Although dietary and herbal supplments are used by roughly 40% of the American population, their side effects aren’t very well known or documented, as their sale and distribution is currently unregulated.

In a recent study by the U.S. Drug-Induced Liver Injury Network, such supplements were found to likely to cause severe damage to the liver. Researchers poured over 109 cases in which someone using these products developed serious health problems. However, despite these findings, it was not confirmed that these supplements actually cause liver damage. Thus far, researchers can only associate the products with the aforementioned side effects.

“There is so little regulation of the many products on the market. We couldn’t possibly begin to figure out which products to target first without doing this research,” explained study leader Dr. Victor Navarro. He added that more research would need to be done in order to learn more about any potential harm they could cause.

Liver injury caused by medication often result in the offending product being removed from the marketplace. However, these studies are considered “preliminary” until they’ve been properly published in a peer-reviewed medical journal.