As a registered dietitian, I learned how the nutrients in the food we eat affect the human body. Fast forward some years later: my interest in inflammation and digestive health now have me fascinated by how the foods we eat affect the bacteria living in our guts.

Think of it this way: those little critters depend on us for their supper. Any food remnant not digested and absorbed by YOU travels to your colon to feed the bacteria there. So it makes perfect sense that what you choose to eat can shape the bacterial community that calls you home…because a vegetarian doesn’t usually opt to eat at a steak house, does he?

So what do healthy bacteria like to eat? The scientific evidence in this area is still in its infancy but at this point, it hints at some particularly interesting (and not terribly surprising) directions. In essence, a healthy diet, filled with fibre from fruits, vegetables, whole grains and beans appears to lead to a happier community of bugs.

For decades, the health benefits of fibre were largely a mystery. How could something that is not absorbed by the human body provide health benefits? The key to understanding this conundrum is bacteria. Bacteria ferment fibre and create short chain fatty acids, which are used by colon cells for nourishment. The short chain fatty acids also lower the pH of the colon, discouraging the growth of bad bugs. Fibre keeps bacteria happy, so they can continue to protect your digestive health and communicate with your immune system, keeping inflammation at bay.

In contrast, the typical Western dietary pattern of high fat, high sugar and low fibre deals a blow to a healthy bacterial community. Inflammation driven by poor diet leads to growth of inflammation-associated bacteria. How does this happen? There are some theories, the first being that a high fat diet stimulates an increase in sulfur-rich bile, favouring the growth of the wrong kind of bacteria. High animal protein may favour the growth of a type of bacteria that produces methane gas, which can slow elimination to a halt. If constipation is an issue for you, take note!

Altering the diet with bacteria in mind can also benefit certain health conditions. The low FODMAPs diet for irritable bowel syndrome eliminates foods with fermentable carbohydrates – like lactose in milk and fructans in wheat – that become fast food for potentially troublesome bacteria in the gut. In addition, some researchers are studying the effect of the paleo diet in autoimmune conditions like multiple sclerosis…with implications for inflammation.

Want to feed your bacteria (and yourself) well? Eat more whole, fresh plant foods such as fruits, vegetables, beans, nuts and seeds. Go meatless once in a while. Shrink your sweet tooth. Remember, you are what your bacteria eat…so be fresh, whole and healthy.

References/Learn More:

Fibre + Microbiota http://onlinelibrary.wiley.com/doi/10.1111/apt.13248/full

Diet + Microbiota http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4216184/

Paleo Diet + Multiple Sclerosis http://terrywahls.com/wp-content/uploads/2014/01/f_DNND-76523-multimodal-intervention-improves-fatigue-and-quality-of-life_022715_23956.pdf