More and more research is showing a direct connection between the condition of the gut and the brain. When you experience stress, you often feel it in your stomach — but it turns out the reverse is also true. Bacteria in the gut can produce various substances that reach the brain through the bloodstream. There are also nerves that run directly from the gut to the brain. Lastly, the gut itself can produce certain substances, such as hormones, that can influence the brain.
Modern technology now allows us to discover more and more about gut bacteria and their impact on our mental and physical health. For example, people with lower levels of certain types of gut bacteria appear to have a higher risk of depression and low moods. Although there is a clear link, it’s still uncertain whether the absence of these bacteria causes depression — or if the depression itself alters the gut flora.
It’s not only depression that’s linked to gut bacteria. Previous studies have looked into the relationship between gut flora and diseases such as Alzheimer’s and Parkinson’s. Research does seem to show a connection. For example, people with Parkinson’s often lack the Prevotellaceae bacterial group, which is usually present in people without the disease.
A healthy diet — rich in fiber from vegetables, fruit, whole grains, nuts, and legumes — supports the growth of bacteria involved in fermenting dietary fiber. Science suggests this likely leads to a healthier gut microbiome.
However, the precise relationship between the exact makeup of gut bacteria and overall health is still unclear. Therefore, we cannot yet say that specific foods must be eaten to directly improve health.