It has long been known that eating fermented foods such as sauerkraut and kimchi can offer many health benefits but exactly why this is the case has remained something of a mystery. Now, researchers at the University of Leipzig in Germany have found that the beneficial effects may be due to the bacteria found in fermented foods boosting the action of the immune system.
The team found the effect when studying proteins found on the surface of cells in fat tissue and immune cells called hydroxycarboxylic acid (HCA) receptors. Most animals have only two types of HCA but humans and other great apes have three. When consumed, lactic acid bacteria – the kind that turns milk into yogurt and cabbage into sauerkraut – produces D-phenyllactic acid in the gut. This binds strongly to this unique third HCA receptor, spurring the immune system into action.
“We are convinced that this receptor very likely mediates some beneficial and anti-inflammatory effects of lactic acid bacteria in humans,” said Dr Claudia Stäubert. “That is why we believe it could serve as a potential drug target to treat inflammatory diseases.”
The researchers believe that the third HCA receptor may have arisen in a common ancestor of humans and great apes to enable them to consume foods that are starting to decay, such as fruits and vegetables picked up from the ground.
They now plan to study D-phenyllactic acid’s effect on the immune system further as well as investigating its effect on fat cells.