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Why fermented food is good for you

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We’ve all been told eating fermented food and yoghurt is good for your gut, and international researchers think they’ve figured out why. The researchers found humans and great apes have receptors on their immune cells that detect the by-products from lactic acid bacteria, the kind commonly found in yoghurt and fermented foods. When cells sense these by-products, they trigger immune cells to spring into action – most likely to mediate beneficial and anti-inflammatory effects. This receptor may have evolved to help the ancestors of humans and apes to eat food that was decaying, like fruit picked up off the ground, the researchers say.

Journal/conference: PLOS Genetics

DOI: 10.1371/journal.pgen.1008145

Organisation/s: Leipzig University, Germany

Funder: This work was supported by the German Research Foundation and by the European Social Fonds and research funding of the Medical Faculty, University Leipzig. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Media Release

From: PLOS

Peer-reviewed                Experimental study                 Humans

Bacteria in fermented food signal the human immune system, explaining health benefits

Ability to detect bacteria may have enabled human ancestors to eat not-so-fresh food

Researchers have discovered that humans and great apes posse­­­ss a receptor on their cells that detects metabolites from bacteria commonly found in fermented foods and triggers movement of immune cells. Claudia Stäubert of the University of Leipzig and colleagues report these findings in a new study published 23rd May in PLOS Genetics.

Consuming lactic acid bacteria – the kind that turn milk into yogurt and cabbage into sauerkraut – can offer many health benefits, but scientists still don’t understand, on a molecular level, why it is helpful to ingest these bacteria and how that affects our immune system. Now, Stäubert and her colleagues have found one way that lactic acid bacteria interact with our bodies. Initially the researchers were investigating proteins on the surface of cells called hydroxycarboxylic acid (HCA) receptors. Most animals have only two types of this receptor but humans and great apes have three. The researchers discovered that a metabolite produced by lactic acid bacteria, D-phenyllactic acid, binds strongly to the third HCA receptor, signalling the immune system their presence. The researchers propose that the third HCA receptor arose in a common ancestor of humans and great apes, and enabled them to consume foods that are starting to decay, such as fruits picked up from the ground.

The study yields new insights into the evolutionary dynamics between microbes and their human hosts and opens new research directions for understanding the multiple positive effects of eating fermented foods. “We are convinced that this receptor very likely mediates some beneficial and anti-inflammatory effects of lactic acid bacteria in humans,” stated author Claudia Stäubert. “That is why we believe it could serve as a potential drug target to treat inflammatory diseases.”

Future studies may reveal the details of how D-phenyllactic acid impacts the immune system, and whether the metabolite also affects fat cells, which also carry the third HCA receptor on their surfaces.


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