Many people take supplements to support joint health but one, sold as a food to help people with arthritic knees, is coming under fire.

Flavocoxid, or Limbrel as it's known on the package, is a prescription medicinal food made of plant roots and bark. It claims to fight inflammation and the pain of osteoarthritis.

Now a new study, just published in the Annals of Internal Medicine, shows that four women out of a study group of 877 developed acute liver damage within three months of starting to use Limbrel. All four stopped taking it, and the liver damaged resolved within weeks.

Unlike drug treatments, medical foods can be marketed without clinical trials proving safety and efficacy. Patients often consider medical foods and supplements to be "natural", so they may not disclose them to their physician.

Play it safe: always talk over your medications, all kinds, with your doctor.

I'm Dr. Cindy Haines of HealthDay TV, with news from today that can lead to healthy tomorrows.