Every time you eat a meal, you’re also feeding the roughly 100 trillion bacteria that call your gut and other organs home. In the past decade, there has been an avalanche of new research and hypotheses about how the microbes that live inside us affect our health, weight, and even mood. We’ve learned that our intestinal flora impact how we process food, contribute to our immune system, and play a role in regulating inflammation.
That’s because these bacteria aren’t just passively hanging out in digestive organs: They have the ability to break down food remnants (read: fiber) and turn them into usable sources of energy, to synthesize vitamins, to crowd out pathogenic bacteria, and to produce molecules that impact gut function. As many as 1,000 different bacterial strains inhabit our intestines, and each of us has our own unique gut fingerprint of microbes comprised of different species in different proportions. Many factors, including genetics, environment, age, and type of birth (vaginal versus cesarean) help to shape our microbiome — and among the most important is diet.
How What We Eat Affects The Gut
Researchers have discovered significant differences between the bacterial profiles of babies who are breastfed and those who are formula-fed. Our microbiome undergoes another dramatic shift when solid food is introduced, and by the time we reach the age of two or three, our flora have morphed into a pattern that largely resembles the adult gut. Different species of bacteria thrive on different foods, so what we eat alters our intestinal makeup. For example, research shows that the standard Western diet, high in protein and fat, has been associated with a greater proportion of bacteria belonging to the Bacteroides genus. A high-carbohydrate, high-fiber diet, such as that consumed by traditional rural populations, has been correlated with higher amounts ofPrevotella bacteria.
The field of microbiome research is still in its toddler years, so despite what you may have read, scientists still haven’t determined what defines a healthy gut pattern, if such a thing even exists. That said, the evidence does suggest that greater microbial diversity — marked by a large number of unique bacterial strains present in the gut — may be protective. Low diversity has been linked to obesity, insulin resistance, heart disease, and gastrointestinal disorders. Loading up on fiber may be one of the most effective ways to produce a more well-rounded gut community, as diets high in vegetables, fruits, and other fiber-rich foods have been associated with greater microbial diversity.
Give Your Gut a Health Boost
While veering from our typical diet for even a few meals can temporarily alter the proportions of different species in our guts, it appears that we are hardwired to return to our original intestinal milieu if the changes aren’t sustained. Current research suggests that it takes much longer to establish new bacterial strains, which means you’ll have to commit to eating more high-fiber foods for the long haul if you want to more permanently enhance the richness of your microbial community. Fortunately, eating a more plant-based diet is in line with general healthy eating recommendations, and is associated with numerous other benefits, including lower cholesterol levels, decreased blood pressure, and reduced risk for heart disease, type 2 diabetes, certain cancers, and other chronic conditions. Isn’t it nice when nutrition advice overlaps?
While our knowledge of the human microbiome is still far too limited to make specific dietary recommendations, the following suggestions may help to nourish a more complex gut environment by fueling beneficial bacteria:
- Eat a wide variety of high-fiber plant foods every single day, including vegetables, fruits, beans, lentils, whole grains, nuts, and seeds.
- Incorporate prebiotic foods. So-called prebiotic foods are rich in the types of fiber that beneficial gut bacteria thrive on. Best bets include onions, garlic, leeks, shallots, asparagus, beets, cabbage, beans, lentils, soybeans, whole wheat, oats, and bananas.
- Enjoy fermented foods. Fermented foods get their tang from lactic acid-producing bacteria, which can survive your harsh digestive tract and actually populate your gut, at least temporarily. While these foods aren’t necessarily probiotics, they may help to support a healthy digestive system. Yogurt with live and active cultures is an easy source, but there are plenty of other deliciously funky options. Experiment with kefir (a fermented yogurt drink), kombucha tea, unpasteurized miso, tempeh (fermented soybean cake), and fermented vegetables with live cultures such as pickles, sauerkraut, and kimchi (look for these in the refrigerated section of your grocery store, since shelf-stable jars don’t contain live bacteria).
Long story short: Pile on the fiber and give the bugs on board in your gut something to chew on.