How your diet affects the gut microbiome

What is the gut microbiome? Does what you eat alter it? While all of the answers can't be unpacked in a single post, we can begin to explore the world inside your gut piecemeal (food pun intended).

Imagine a 30 ft long tube filled with trillions of bacteria, viruses, and fungi. Sounds like a nightmare right? Well that is indeed our gastrointestinal (GI) tract, and the balance in composition of all those different organisms is what is commonly called the Gut Microbiome. It has important implications for your health, with its potential responsibilities growing as research continues to find new ways the microbiome influences much more than just your GI tract.

The bacteria in your gut are hard at work. They help break down food, regulate the immune system, and even help defend against other harmful germs. You would think that doctors would have a concrete understanding of which bacteria are good and bad, but while there are certainly well-established superheroes and villains on either side, the specific makeup that creates the ideal environment for your gut is not yet known. What is known is that (among thousands of other variables) the food you eat, antibiotics you take, and even how you were born all play a role in forming your gut's microbiome.


How does the food you eat alter the microbiome?

Dietary fiber (fruits, nuts, whole grains) is crucial both to get your gut moving (and will be the subject of a future post all on its own), strengthen it, as well as reduce inflammation. That last point is particularly important, as inflammation is associated with GI symptoms, and in the long term correlates with risk of developing cancer. Eating dietary fiber over time creates a beneficial feedback loop, in that fiber serves as fuel for your gut's good bacteria, thus increasing their abundance relative to some of the villain bacteria we alluded to earlier, ultimately making your gut stronger over time. 


What is the best diet for the gut microbiome?

Better understanding how your diet influences the biome has been the focus of a lot of interesting research. In my opinion, there are two important facts that anyone interested in the health of their gut should know. First of all, it takes as little as two weeks of a diet low in dietary fiber to start to alter your biome. Researchers tested this by taking rural South Africans who had a healthier, high-fiber diet, and switching it with African Americans with an unhealthy, high fat, low fiber (AKA the average American) diet. The food changes resulted in remarkable changes in biomarkers of cancer risk and associated microbiota. Switching African Americans to the high fiber diet had the reverse effect. That fact still shocks me.

Secondly, a plant-based is much safer for your GI tract than an animal-based diet. The carcinogenicity (= possibly cancer causing nature) of processed meats is well established, and is probably the most dangerous thing you do to your gut. Truthfully, I'm not a strict vegetarian on account of meat being delicious but knowing these two simple facts has drastically altered the ratio of vegetables to meat I choose to eat. Foods that contain polyphenols such as fruits, vegetables, tea, even red wine can beneficially diversify your gut flora. The same study showed that milk and soda, among other staples of a western diet, minimizes diversity in your microbiome. There's a huge trend in studying fermented foods (think kimchi, kombucha, even plain yogurt) with data showing a lot of promise in its beneficial effects on the gut.

Clearly this is just a starting point for many future discussions we will have about the gut microbiome. Learning about the biome is a classic example of how the more you start to learn about it, the more you realize how much there is left to learn.

-The Gut Doc


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