Lactic bacteria of yogurt and sauerkraut stimulate the immune system


How lactic acid bacteria stimulate our immune system

Lactic bacteria from fermented foods, such as yogurt and sauerkraut, play an important role in our health. So far, however, it is unclear where this effect comes from. A German research group has found in a recent study that bacteria from fermented diets interact directly with the immune system. Humans and monkeys are the only mammals that even have their own receptor for lactic acid bacteria.

A research team at the University of Leipzig found a receptor in human cells, which is activated by signals that are emitted by lactic acid bacteria. The receptor creates a direct interaction between the immune system and the bacteria. Researchers see the receptor as the reason for the positive effects of fermented foods on human health. The results of the study were recently published in the renowned journal "Plos genetics".

Foods that have been fermented by lactic acid are considered healthy. From where the health promotion aspect comes, so far it is unclear. Researchers from Leipzig are in the way of secrecy. (Image: PhotoSG /

The mystery of probiotics

Lactic fermentation produces popular foods, from sauerkraut to yogurt. Probiotic products are considered health promoters. The exact reason behind this is not yet known. Lactic acid bacteria, which are also part of the intestinal flora (intestinal microbioma), have been blamed for the positive aspects. The research group at the University of Leipzig has now come a step further in the unfolding of events. They found that humans and monkeys are the only mammals that have their own receptor that responds to the signs of lactic acid bacteria.

How we interact with lactic acid bacteria

Leipzig scientists have shown for the first time how lactic acid bacteria interact with our bodies. They studied certain proteins found on the surface of cells. So-called hydroxycarboxylic acid (HCA) receptors are present in most mammals. But while all mammal species have only two different receptors of this type, humans and monkeys have three of them. The HCA3 receptor appears to be especially present for the communication between the immune system and the lactic acid bacteria.

Why do we react so well to fermented foods?

"We combine evolutionary, pharmacological, immunological and analytical methods and investigate why this receptor was preserved during evolution," reports study leader Dr. med. Claudia Stäubert in a press release. According to the researchers' theory, the receptor was applied at a time when our human ancestors changed their lifestyle and fewer fresh fruits were available. For this purpose, more and more fallen fermented fruits were eaten. In this scenario, the HCA3 receptor may be an important advantage.

How does the interaction happen?

"We found in the course of this study that a substance, which occurs at high concentrations in fermented foods such as sauerkraut, activates the HCA3 receptor and therefore influences the function of the human immune system," Stäubert summarizes. In the research, the team showed that after consuming sauerkraut, the levels of a substance called D-phenyl-lactic acid in the blood, which is released from the lactic acid bacteria. The concentration is sufficient to stimulate the newly discovered HCA3 receptors. As a result, the immune system and adipose cells are informed through the receptor that, on the one hand, foreign substances and, on the other hand, energy have entered the body.

Is the new receptor behind the health promoting effects?

"Numerous studies show positive effects that are mediated by lactic bacteria and fermented foods," emphasizes the study leader. The Leipzig team is convinced that the uncovered receiver should be responsible for at least some of these effects. In the following studies, the task of D-phenylacetic acid will be investigated. In addition, the researchers want to find out whether HCA3 Rezepor is suitable as a therapeutic target for digestive diseases, such as irritable bowel syndrome.

Further studies on fermented foods

Other studies have recently investigated the beneficial effects of fermented foods. A Korean study highlighted the health benefits of kimchi. Fermented cabbage is similar to sauerkraut and is extremely popular in Korea. According to studies, the traditional dish may work against hypertension and overweight. For more information, see the article: Preventing overweight and high blood pressure with kimchi. (Vb)


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