Scientists have found that a gas that smells of rotten eggs is naturally present in the knee joint and may help protect against inflammation, according to new research.

A comparative study of people with rheumatoid arthritis, osteoarthritis and healthy individuals found the “rotten egg” gas, called hydrogen sulfide (H2S), resides in the synovial fluid in the knee joint. Synovial fluid acts as a buffer between the cartilage of the joints and is found in the cavities of the joints.

Compared to the control group of healthy individuals, scientists at the Peninsula Medical School and rheumatologists at the Royal Devon and Exter National Health Service Trust in the U.K. found patients with rheumatoid arthritis had higher concentrations of H2S in their synovial fluid and four times as much in blood samples.

These results, suggesting that H2S may be a natural mediator for controlling inflammation, add to earlier research from the same team that identified a molecule that safely releases low amounts of the “rotten eggs” gas and could lead to a therapeutic option for patients with chronic inflammatory diseases.

The team, whose findings were published in the current issue of the Annals of the New York Academy of Sciences, received a grant of just under $200,000 over three years for further studies.

“By identifying a clear link between levels of H2S in synovial fluid and inflammation we can apply our earlier synthesis of a new molecule to control the delivery of H2S more effectively,” said Dr. Matt Whiteman, from the Peninsula Medical School, who led the study. “We leave the way open for the development of H2S-based therapies that provide the benefits of traditional anti-inflammatory drugs without their unpleasant side effects.”

An estimated 46 million Americans report having some form of arthritis, according the Center for Disease Control and Prevention website.

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