Gut bacteria process bioactive plant-based dietary compounds and, in turn, produce metabolites not synthesized by their human hosts. Many of these metabolites influence human health by regulating physiological processes such as nutritional homeostasis, energy expenditure, and immunity. A 2017 study demonstrated that microbial metabolites produced from flavonoids modulate the body’s response to influenza infection.

Flavonoids are bioactive compounds present in a variety of fruits and vegetables. More than 4,000 flavonoids have been identified in the human diet. When gut bacteria called Clostridium orbiscindens break down flavonoids, they produce a metabolite known as desaminotyrosine (DAT). DAT helps the body produce interferon, a signaling molecule that activates the immune system.

The authors of the rodent study gave mice DAT for seven days and then infected them with influenza. The mice continued to receive DAT for 14 days post-infection. A control group of mice received no DAT.

The mice that received the DAT exhibited lower levels of viral RNA and less epithelial damage and apoptosis in their lungs. They also experienced less weight loss and were less likely to die from their infection than control mice. Interestingly, if mice were given DAT two days post-infection, they had worse outcomes than the mice who received DAT before infection, suggesting that DAT primed the immune system for an appropriate response to an immune challenge.

These findings suggest that dietary compounds can boost immune function and highlight the importance of regular consumption of these protective compounds to prime the immune system.

• Link to full study.

Press release: https://www.sciencedaily.com/releases/2017/08/170803141048.htm