Eating to feed your gut microbes

By Samantha Stadmiller

Most people think about what they eat and how it will affect their body. For example, when you reach for an apple, or some other type of produce, you often think that it is healthy and it will make you feel good. But have you ever stopped to think about how the food you’re eating will affect the microscopic organisms in your body? It turns out that you have just as many, if not more, microbes in your body as you do human cells. This collection of tiny organisms is called your microbiota and has become a hot topic for both researchers and the general public.

Microbes exist all over your body from the skin to the blood. Your gut, however, is home to your body’s most diverse community of microbes. The composition of your gut microbiota is linked to risk factors for many chronic diseases such as diabetes, cancer, cardiovascular disease, inflammatory bowel disease, and obesity. It is now also known that diet plays a large role in the types of microbes in your gut, therefore, by eating certain types of foods you can increase the diversity and shift the composition of your microbiota.

So what do your gut microbes do and why are they so important to your health? Although they perform numerous metabolic functions, one of their main beneficial roles is to break down indigestible fiber to short chain fatty acids (SCFAs). SCFAs include small compounds like acetate, butyrate, and propionate that are used by the body as energy sources. SCFAs are essential to maintaining gut and colon health and, more recently, they have been shown to reduce risk factors for a variety of diseases. Specific types of gut bacteria, such as  Bifidobacterium, Lactobacillus, Roseburia, and Eubacterium, are better at producing these SCFAs than others and their abundance is commonly affected by diet. In fact, your gut microbiota composition is affected by a variety of environment factors including diet, exercise, antibiotic use, stress, and even where you live.

One study published in the Journal of Translational Medicine in 2017 examined the effects of different diet types on the gut bacterial community by going back and compiling nearly five decades of gut microbiome studies in humans. They were able to comprehensively characterize the effect of a specific diet type on gut bacterial diversity and composition. Of particular interest was the comparison of a typical Western diet high in animal protein and fat, and low in fiber, to a Mediterranean diet rich in unsaturated fatty acids, fiber, fruits, vegetables, and nuts with moderate consumption of fish and poultry. The results were nearly opposite for the two different diets. Those on a Western diet showed decreased numbers of total bacteria, bacterial diversity, and those bacteria which are responsible for making SCFAs. On the other hand, those on a Mediterranean diet showed an increase in bacterial diversity including those that produce SCFAs. The stark comparison of these two diets and their effect on microbial communities highlight the potential contributions of these bacteria to human health.

It is undeniable that your microbiota plays a large role in overall health and wellness. Although much research has been done in this field, it is still in the preliminary stages and the National Institutes of Health (NIH) has initiated an effort to characterize the genes of these different bugs through the Human Microbiome Project. Further research will hopefully provide more direct mechanisms of how one’s diet can affect the health of the human host as our knowledge of these microscopic wonders continues to grow. So next time you reach for your fork, take a minute, and think about how food might affect your microbes.

Interested in reading more? Consider picking up I Contain Multitudes: The Microbes Within Us and a Grander View of Life by Ed Yong

Peer-reviewed by Evan Paules