The Bacteria that Mold Your Brain

Microbiology, Neuroscience

By Daniel Hass, 4th year Neuroscience PhD student

“Tell me what you eat, and I will tell you what you are”

This phrase, coined by Jean Anthelme Brillat-Savarin in the Physiologie du goût (The Physiology of Taste) was over a century ahead of its time.

Food Cheese

Some foods are better by virtue of their microbes. Cheese is one such food, matured by several types of bacteria (Wikimedia)

The commonly held aphorism is true in more ways than one. In one respect, it means that ‘the food you eat becomes a part of your person’,and this has long been known—amino acids from digested proteins are incorporated into our own proteins, and the energetic sources from our diet, such as sugars or fatty acids, are added to our own stores of energy. In another respect, the quote can mean that the food you eat influences ‘who’, or ‘what kind of person’ you are. This interpretation is also true– the substances you consume can alter your brain chemistry, and thus behavior (‘who’ you are), in manners too complex for a single blog post.

I will discuss the ways in which food affects our brains in a four-part series. Each part will examine a critical substance in food (microorganisms, carbohydrates, fats, and proteins) and the ways in which it alters or is central to behavior.

This first of these parts concerns a fascinating route by which diet can change the brain, and that is through our microbiome, the ecosystem of microorganisms such as bacteria, archaea, protozoa, fungi, and viruses that live on and interact with our bodies. Each adult has about 1 kg of these microbes, which are highly diverse, cumulatively containing approximately 100 times as many genes as the human genome.

The diversity and composition of these microbes in the gut is strongly influenced by diet.