Some Japanese researchers found that butyrate, which is a compound that’s produced by bacteria fermenting dietary fiber in the gut, can actually improve T regulatory cell production. T regulatory cells help keep the immune system in balance, and a lot of people with autoimmune disease have impaired T regulatory cell function. Essentially the study is showing that the gut bacteria can directly influence the immune system. We’ve known for a while that butyrate, this compound, had an anti-inflammatory effect, but this study showed a particular mechanism for how it does that. This is just one example of many, many studies now, it seems,[ ] that are showing a connection between our gut bacteria and aspects of health, which we may not have even realized would be related to our gut, like our mood, depression, skin, etc.