Experts at Ohio State University have identified a type of gut bacteria that reduces the risk of heart disease. The heart health benefits of this bacteria, Eubacterium limosum, were previously unrecognized.
The activity of E. limosum reduces the production of a chemical within the intestines that is linked to clogging of the arteries in a condition known as atherosclerosis. After the chemical is produced, it travels through the bloodstream to the liver where it is converted into a more harmful form.
The researchers linked the beneficial behavior of E. limosum to a specific family of proteins, and this link helps to explain how good gut bacteria positively contribute to human health.
In the gut, good bacteria compete with bad bacteria for the same nutrients. By helping to eliminate the bad microbes, the good bacteria may prevent health problems that can develop as a result of metabolic issues.
More research is needed, but the experts believe there is a lot of potential for E. limosum to be used for therapeutic purposes. Previous studies have already established that the bacteria calms gut inflammation.
“Over the last decade, it has become apparent that bacteria in the human gut influence our health in many ways,” said study senior author Professor Joseph Krzycki. “The organism we studied affects health by preventing a problematic compound from becoming a worse one.”
“It’s too soon to say whether this bacterium could have therapeutic value. But that’s what we’re working toward.”
The chemical linked to clogged arteries is called trimethylamine (TMA). This is produced during metabolism when intestinal microbes – usually the bad type of gut bacteria – interact with certain nutrients from food. One such nutrient is L-carnitine, a chemical compound in meat and fish that is often used as a supplement to improve recovery after exercise.
The researchers discovered that E. limosum interacts with L-carnitine in a different way in the gut, eliminating L-carnitine’s role in production of TMA.
The bacteria’s beneficial behavior has been attributed to the protein MtcB, an enzyme involved in demethylation. By removing a methyl group, this process changes a compound’s structure or function.
The study revealed that when E. limosum is exposed to L-carnitine, the bacteria synthesizes the MtcB protein to specifically target and cut off L-carnitine’s methyl group.
“The bacterium does this for its own benefit, but it has the downstream effect of reducing the toxicity of TMA,” said Professor Krzycki. “Up until now, the only known gut microbial reactions with L-carnitine involved converting it into its bad form.”
“We’ve discovered that a bacterium known to be beneficial could remove a methyl group and send the resulting product down another pathway without making any other harmful compounds in the process.”
According to Professor Krzycki, finding this significant health benefit in one species of gut bacteria suggests there is still a lot to learn about how gut bacteria can influence health outcomes associated with human metabolism.
“MtcB is part of a family of proteins with thousands of representatives that may use different compounds and change what nutrients bacteria consume in the gut,” said Professor Krzycki. “These proteins may behave very similarly chemically, but using different compounds obviously can create big changes as far as biology goes.”
The study is published in the Journal of Biological Chemistry.