New meaning to the term “gut feeling”: gut bacteria and the brain

science, microbiome, microbiology, bacteria art — Illustration of the human small intestine, home to countless bacteria. These bacteria colonize the villi as shown here.

We’ve been told for years that our body is composed of cells, human cells. We’ve also heard about the ‘good’ bacteria that inhabit our bodies and help us digest different types of food and can even provide us essential vitamins and nutrients. Most of this occurs in the small intestine where our food starts to become our poop. Pardon the pun, but what we’ve been told is grossly underestimated. First, they outnumber our cells…by a lot (10 to 1). That doesn’t include the overwhelming majority of genetic material in or on our bodies that is not ours (see infographic here).

More and more evidence is being presented showing the intimate relationship between man and his flora. First, these little guys provide more than just vitamins including some B vitamins and K. They also are able to absorb essential minerals, like calcium and iron, from our food for us to use later. They also provide a physical barrier to defend against infection from pathogens that may enter your digestive tract.

Recent research has shown a connection between gut bacteria and childhood eczema (here).

Another study indicates small molecules secreted by bacteria can prevent inflammatory bowel (here).

How about gut bacteria affecting the onset of rheumatoid arthritis (RA) in susceptible individuals (here).

One study found by eating probiotic yogurt, women had lower occurrence of depression (here).

There is also the new technique of curing chronic colon inflammation with a fecal transplant (here and here).

These are just a few, picked examples establishing a relationship between bacteria, or the types of bacteria, in our guts and our health. What about examples?

Autism and gut bacteria

Research now suggests a link between autism spectrum disorder (ASD) and environmental factors. These may include a number of factors, but what about gut bacteria?

A recent article in PLoS ONE shows a significant decrease in GI bacterial diversity among autistic subjects compared to normal subjects. Some common bacterial genera were missing in autistic subjects, especially Prevotella. The missing bacteria were common carbohydrate-degrading species or fermenters. This, and other, evidence could explain the common GI irritability in autistic children. There is also some reports of changes in diet (gluten-free, caseine-free) lessening the effects of autistic symptoms.

It is still early, and much more needs to be studied. However, you shouldn’t think of yourself as a single entity. You and your bugs are a package deal.