Can We Improve Our Microbiome?
The microorganisms living in our intestines influence digestion, metabolism, and immune function. Researchers are also discovering intriguing connections with brain health and aging.
The encouraging news is that we can influence our microbiome through the foods we eat and other everyday choices.
Scientists are learning more about how dietary fiber, fermented foods, prebiotics, and probiotics affect intestinal microorganisms.
Although many questions remain, there are practical steps we can take today.
Diet May Be the Most Important Factor
What we eat influences which microorganisms thrive in our intestines and what substances they produce.
Many beneficial bacteria use dietary fibers and plant compounds that our digestive enzymes cannot break down.
Vegetables, nuts, seeds, legumes, and whole grains provide nutrients that support microbial activity.
For people following low-carbohydrate diets, non-starchy vegetables, nuts, seeds, and other fiber-containing foods offer alternatives to grains and legumes.
Eating a variety of suitable plant foods is one practical way to support a healthy microbiome.
What About Carnivore Diets?
Carnivore diets eliminate most or all plant foods, including dietary fiber.
Some people report improvements in digestive symptoms and metabolic health, but rigorous long-term studies are lacking.
Although fiber supports many beneficial gut bacteria, we don't yet know whether a fiber-free carnivore diet necessarily leads to poorer gut health.
The microbiome can adapt to different diets, but the long-term health consequences of these changes remain uncertain.
Fiber and Prebiotics
Certain gut bacteria ferment dietary fiber, producing short-chain fatty acids that help maintain intestinal health.
Prebiotics are substances that microorganisms use in ways that provide a health benefit.
Examples include inulin and fructooligosaccharides, found naturally in onions, garlic, asparagus, and artichokes.
Prebiotic supplements are also available.
Research suggests that certain prebiotics can improve digestive function and encourage the growth or activity of beneficial microorganisms.
Their effects on blood glucose, weight, and other metabolic outcomes are still being investigated.
Increasing fiber gradually may help avoid gas and bloating.
Fermented Foods
Yogurt, kefir, sauerkraut, kimchi, and certain cheeses are examples of fermented foods.
Some contain living microorganisms that may interact with our intestinal microbiome.
A 2021 Stanford clinical trial found that a diet rich in fermented foods increased microbial diversity and reduced several inflammatory markers.
More recent research has produced mixed results, although some studies suggest benefits for digestive health.
Fermented foods also provide nutrients beyond their possible effects on the microbiome.
Including fermented foods we enjoy and tolerate well may be a worthwhile addition to a healthy diet.
For people following low-carbohydrate diets, plain yogurt, unsweetened kefir, and fermented vegetables without added sugar are good options.
Are Probiotic Supplements Worth Taking?
Probiotics are live microorganisms that provide a health benefit when consumed in adequate amounts.
Research has identified benefits from certain probiotic strains for specific digestive conditions, including some forms of diarrhea.
Scientists are also studying their potential effects on inflammation, metabolic health, and brain function.
Results have been encouraging in some studies, although benefits depend on the particular strain, dose, and condition being treated.
Not every probiotic product has been adequately tested, and taking more bacteria does not necessarily produce greater benefits.
For most healthy adults, probiotics are an option worth understanding rather than a supplement everyone needs.
People with weakened immune systems or serious illnesses should discuss probiotic use with their healthcare professionals.
See the section on Supplements for more about the benefits, limitations, and safety of commonly used supplements.
Can We Test Our Microbiome?
Commercial stool tests can identify many of the microorganisms living in our intestines, providing a fascinating picture of our individual microbiome.
Some companies analyze these results and recommend dietary changes, prebiotics, or probiotics intended to support gut health.
These tests may help us better understand our microbial communities, and researchers are working toward more personalized recommendations.
However, scientists have not yet established what constitutes an ideal microbiome, and different testing methods can produce different results.
Microbiome testing is a promising technology, but we still need stronger evidence that using the results to guide diet or supplements leads to better health outcomes.
As the science advances, these tests may become increasingly useful for personalized nutrition and healthcare.
What About Antibiotics?
Antibiotics can substantially change the gut microbiome because they affect beneficial bacteria as well as harmful ones.
Fortunately, microbial communities often recover after treatment, although some changes may persist.
Avoiding unnecessary antibiotics is one way to protect our microbiome.
However, antibiotics remain essential for treating many bacterial infections and should be used when medically appropriate.
What Matters Most as We Grow Older?
Our microbiome changes throughout life, influenced by diet, medications, physical activity, and health.
Researchers are increasingly interested in whether supporting a healthy microbiome might help reduce inflammation, improve metabolic function, and promote healthier aging.
Although these possibilities are still being studied, we already have several reasonable ways to support intestinal health.
Eating a variety of fiber-containing foods, including fermented foods when appropriate, staying physically active, and avoiding unnecessary antibiotics are sensible starting points.
Prebiotics and selected probiotics may provide additional benefits, depending on individual circumstances.
We don't need to wait for every scientific question to be answered before making choices that support our gut health.
And as microbiome research advances, we may discover new opportunities to improve health through personalized nutrition and targeted treatments.
Learn More
Explains what probiotics are, where clinical evidence supports their use, and potential safety considerations.
Explains how prebiotics differ from probiotics and which foods contain them.
Discusses fermented foods and their potential health benefits.
Dr. Nick Norwitz explains how diet and lifestyle influence the gut microbiome, including the potential benefits of fermented foods and probiotics, the debate over dietary fiber, and what scientists are still discovering.