You are what your gut bacteria eat
New study shows lifestyle, not genes, most important in shaping microbiome; you can improve your gut microbiome by making the right food choices
Our fascination with germs took an interesting turn in the past decade.
After waging all out chemical warfare against microbial life in our living habitats and inside our bodies – think endless home disinfectants, bleaches, and antimicrobials, and antibiotics prescribed broadly and indiscriminately – microbial life is finally getting some respect.
Each of us is a universe of microorganisms. We host trillions of microbes. Bacterial cells outnumber our cells 9 to 1, their genetic material outweighing ours 150 to 1. Not surprisingly, the inhabitants of planet you affect your health and shape, in much the same way that all living things on earth affect the future of our planet.
Recent studies find that the state of the inhabitants of our gut may affect our immune system, our weight status, our susceptibility to disease, our energy levels, our mental state and our mood.
How does one get the kind of microbial society that’s most conducive to wellness? Do our genes determine our gut environment, which in turn attracts and allows certain kind of bacteria to prosper, or is lifestyle more important? We know that siblings have similar microbiomes, but is this the result of shared genes, or shared habits and environment?
Israeli scientists from the Weizmann Institute of Science studied 1046 people with diverse ancestral origins. The researchers collected genetic data and studied each participant’s microbiome, and also his dietary and lifestyle habits, medications and additional measurements.
They found that sharing genetic makeup mattered much less than sharing an environment. In fact, they estimate that just 2 percent of gut microbiome is genetically inherited. Sharing a home and a diet predicted similarities of microbiome.
Moreover, the study, which was recently published in Nature, shows that certain microbiome consistencies predicted many health characteristics, from BMI and waist size to glucose tolerance and cholesterol levels.
In other words, you affect your microbial population through your lifestyle, and in turn, your microbiome affects your wellness trajectory. Genetic makeup matters much less than your lifestyle choices.
“We found that the gut microbiome is significantly associated with multiple environmental factors. Diet was amongst the strongest factors that accounted for a highly significant fraction of the microbiome composition of different people,” says lead author Eran Segal.
Tips for a healthy microbiome
These are early days in the study of our interaction with out intestinal inhabitants, so expect many new developments, but a few strong themes are already emerging.
“While we still don't know what a "healthy" microbiome is, one early message from the research is that ecological diversity of gut flora tends to mirror nutrient diversity. So I often recommend my patients focus on the quality of their food first (as opposed to random calorie cutting) and increase the range of foods they eat,” advises Dr. Rusha Modi, internist, gastroenterologist and researcher at the Keck Medical Center of the University of Southern California. “Increasing fiber intake is an easy way to do this since it comes in many different fruits and vegetables. The other strategy I recommend is to have regular meal timing and sleep cycles. Circadian rhythms have been implicated in regulating the function of gut bacteria. In our hectic, modern lifestyle we often sleep and eat irregularly. This is one of the reasons jet lag often prompts constipation. Limiting unnecessary medications such as antibiotics is useful as well as they can often deplete gut bacteria rapidly,” he adds.
Dr. Suneil Koliwad, diabetes researcher at University of California San Francisco and Chief Medical Officer at Suggestic has similar recommendations: “A metabolically healthy microbiome is exceptionally diverse, and this diversity drops progressively in the run-up to overt type 2 diabetes. In particular, some species that are highly abundant in relatively lean, healthy individuals, are lost in the microbiomes of people with diabetes. So, the goal of preventing type 2 diabetes by manipulating the microbiome focuses on maintaining healthy levels of “good” components of the overall bacteria in the gut, and retaining its overall diversity.
"How can one do this? The data in this area are still emerging, but early signs suggest that focusing on vegetables and fruits, and foods high in fiber, are key to the maintenance of a healthy microbiome. Dietary fiber, including non-digestible carbohydrates “roughage” provide food for intestinal bacteria. In consuming these dietary nutrients, the bacteria produce their own products, which make their way into our bloodstreams and affect our metabolism in a beneficial way. Although there are not strong data indicating that the consumption of meat is bad for the microbiome, there are data suggesting that excessive red meat consumption, for example eating too much barbecue, can influence the function of our guts in ways that produce potentially unhealthy molecules. Finally, there is emerging evidence that consuming too many highly processed foods has a negative impact on the microbiota. It remains unclear what effects non-nutritive (artificial) sweeteners have on the microbiome, but this an active research area right now.”
The key points to keep in mind when thinking about the health of your microbiome – and that’s from several experts I was in touch with for this piece – is to eat whole plant foods, lots of fiber, and reduce refined and highly processed foods.
Which I’m sure sounds familiar.
Ends up beneficial bacteria thrive on the same foods we hosts do.