Study: Stroke survivors lacking antioxidant carotenoids in their gut flora

GOTHENBURG, Sweden — Researchers at the University of Gothenburg along with the Chalmers University of Technology earlier this month demonstrated that an altered gut microbiota in humans is associated with symptomatic atherosclerosis and stroke. 

These findings were presented in a study published in Nature Communications on Dec. 4.

The researchers compared a group of stroke patients with a group of healthy subjects and found major differences in their gut microbiota. In particular, they showed that genes required for the production of carotenoids were more frequently found in gut microbiota from healthy subjects. The healthy subjects also had significantly higher levels of a certain carotenoid in the blood than the stroke survivors.

Carotenoids are a type of antioxidant, and it has been claimed for many years that they protect against angina and stroke. Thus, the increased incidence of carotenoid-producing bacteria in the gut of healthy subjects may offer clues to explain how this affects disease states.

Carotenoids are marketed today as a dietary supplement. The market for them is significant, researchers noted, but clinical studies of their efficacy in protecting against angina and stroke have produced varying results.

Jens Nielsen, professor of systems biology at Chalmers, suggested that it may be preferable to take probiotics that contain types of bacteria that produce carotenoids.

"Our results indicate that long-term exposure to carotenoids, through production by the bacteria in the digestive system, has important health benefits," Nielsen noted. "These results should make it possible to develop new probiotics. We think that the bacterial species in the probiotics would establish themselves as a permanent culture in the gut and have a long-term effect."