Sauerkraut, tempeh, kimchi, fermented foods are known and eaten all over the world. It is that the consumption of fermented foods is associated with improved health. These benefits would be caused by the presence in these foods of an antibacterial molecule that interacts with a receptor present on the surface of immune cells.
Fermentation is a biochemical reaction used by different microorganisms to produce energy from sugar in the absence of oxygen.
In lactic fermentation, certain types of bacteria transform the carbohydrates present in food into lactic acid, which acidifies the medium and prevents the proliferation of pathogenic or undesirable microorganisms, such as molds.
This property has been used since time immemorial to increase the shelf life of perishable foods, whether milk (yogurt), certain vegetables such as cabbage (sauerkraut in Europe, kimchi in Korea) or legumes such as soybeans. (Japanese nattō or Indonesian tempeh).
In addition to preserving foods, lactic fermentation improves their digestibility, increases their content in several essential elements (proteins,
amino acids, fatty acids and vitamins from bacteria) and, a not insignificant property, makes it possible to diversify the diet by generating new aromas, flavors and textures.
Fermented foods improve immunity and reduce the risk of certain cancers
Beyond their nutritional benefits, several studies have shown that lactic acid bacteria present in fermented products can modulate the activity of the immune system and exert several positive effects on health.
For example, a study of 32,606 men recently showed that those who consumed 2 servings of yogurt per week had a 20% lower risk of developing adenomas (precancerous lesions) in the colon compared to those who did not. never consumed.
A very interesting study provides a better understanding of this interaction between fermentation and immunity: German researchers have just shown that a metabolite produced by lactic acid bacteria during fermentation, phenyllactic acid, binds specifically to a receptor called HCA3 (hydroxycarboxylic acid receptor 3.
Like its close cousins HCA1 and HCA2, the HCA3 receptor is present in adipocytes, where it is involved in controlling the release of fatty acids into the circulation. However, HCA3 differs from other members of this family by being the only receptor to be present in very large quantities on the surface of immune cells such as monocytes (macrophages, for example).
The researchers observed that the addition of physiological concentrations of phenyllactic acid, easily achievable by the consumption of fermented foods, causes the activation of these monocytes, which raises the interesting possibility that the activation of the HCA3 receptor present in the levels of these cells may play an important role in the beneficial effect of fermented foods on immune function.
Our body has always loved fermented foods
The interaction of a metabolite produced by lactic acid bacteria with the HCA3 receptor is interesting, because a genetic analysis carried out by the authors shows that this receptor appeared relatively late in evolution, around 15 million years, and is present only in great apes and humans.
According to the authors, the selection of this new gene by hominids could be due to the fact that great apes began at this time to leave the forest for a more terrestrial life, which increased the probability of having to feed on fallen foods. on the ground and which were therefore more likely to be fermented.
The presence of a gene allowing the immune system to detect the presence of a molecule with antimicrobial activity such as phenyllactic acid in these fermented foods could therefore provide benefits for survival. This type of positive selection is similar to what is proposed for the alcohol dehydrogenase gene, which appeared at the same time, and which allowed great apes to consume fruits damaged by alcoholic fermentation. In short, we have been enjoying the benefits of fermentation for a long time!
Source
Zheng X et al. Yogurt consumption and risk of conventional and serrated precursors of colorectal cancer. Gut Peters A et al. Metabolites of lactic acid bacteria present in fermented foods are highly potent agonists of human hydroxycarboxylic acid receptor 3. PLoS Genet. 15: e1008145.
