There are more than 500 species of bacteria in the human gut. This internal ecosystem, which scientists call the gut microbiome, contains both health-promoting and disease-inducing bacteria, and one of the keys to good health is maintaining the right balance of the two. When the gut microbiome is healthy, friendly bacteria digest milk sugar (lactose) and protein, increase the absorption of minerals, manufacture vitamins B and K, make essential and short-chain fatty acids, and prevent dysbiosis—the overgrowth of bad bacteria.
Lower disease risk
These friendly bacteria can even lower the risk of specific diseases and disorders, like depression, autoimmune disease, heart disease, and diabetes.
- Mental health problems. Maintaining an optimal level of gut probiotics through a probiotic-rich diet and supplementation can reduce depression, reduce anxiety in chronic fatigue syndrome, help relieve stress-related psychological symptoms, boost mood in healthy people, and enhance memory and concentration, research shows.
That’s because of the gut-brain axis—a direct link from the brain to the gut via the vagus nerve. The link is so strong that some researchers are now talking about psychobiotics: supplemental probiotics like Lactobacillus helveticus and Bifodobacterium longum that are uniquely effective in helping to restore and improve mental health.
- Autoimmune disease. There are approximately 100 different autoimmune diseases in which the immune system mistakenly attacks a part of the body as if it were a foreign invader. They include type 1 diabetes, celiac disease, rheumatoid arthritis, Hashimoto’s disease, and multiple sclerosis (MS).
Dysbiosis is a feature of most cases of autoimmune disease, and many studies suggest that correcting it with a probiotic supplement can help relieve the symptoms of autoimmunity. Researchers reported in the journal Nutritional Neuroscience that people with MS who took a probiotic supplement for six months had higher levels of brain-derived neurotrophic factor (a compound that helps nerve cells grow and survive), lower levels of IL-6 (an inflammatory biomarker), and less fatigue, pain, and depression (three common symptoms of MS).
In a study published in the British Journal of Nutrition, people with rheumatoid arthritis who took a supplement that contained both probiotics and prebiotics (nutritional factors that nourish probiotics) had less inflammation, joint stiffness, pain, and swelling, and better blood sugar control than people who took a placebo.
In Taiwan, investigators reported that people with type 1 diabetes who took a probiotic supplement had lower, healthier blood sugar levels and less inflammation than those in the placebo group.
- Cardiometabolic disorders. This category of interrelated health problems (also called the metabolic syndrome) includes high blood pressure, high blood sugar, low HDL cholesterol, high triglycerides, and abdominal obesity (excess belly fat). Cardiometabolic conditions also include fatty liver disease, polycystic ovary syndrome, and gout.
Scientists are finding that the gut microbiome plays a role in all of these problems, probably because dysbiosis triggers chronic, low-grade inflammation and interferes with the digestion and assimilation of macronutrients (carbohydrate, fat, and protein).
Enriching the diet with probiotics through food or supplements may lower high blood pressure, high blood sugar, high LDL cholesterol, and high triglycerides, research suggests. It can trim abdominal fat, reduce body mass index, reduce fat in the liver, lower biomarkers of liver toxicity, and decrease inflammatory biomarkers.
- Digestive diseases. It’s no surprise that friendly gut bacteria improve gut health, reducing the risk of digestive disease and helping to treat and reverse gut problems. Probiotics have been used to treat irritable bowel syndrome, stomach ulcers, ulcerative colitis (a type of inflammatory bowel disease), celiac disease, and antibiotic-induced diarrhea.
In fact, a prescription supplement called VSL#3 has been developed specifically to treat irritable bowel syndrome and ulcerative colitis. Probiotics have also been used to treat bacterial infections in the gut, such as Helicobacter pylori and small intestinal bacterial overgrowth.
What to eat to support your gut
The best way to maintain your gut microbiome is to eat a whole-foods diet, especially foods that are rich in prebiotics. (Probiotics are beneficial bacteria, and prebiotics feed friendly bacteria.)
They consist of foods rich in soluble fiber and colors, and are found most abundantly in whole grains, beans, peas, vegetables, fruits, nuts, and seeds.
Foods that are rich in these nutritional compounds include artichokes, asparagus, avocados, bananas (under ripe), barley, beet root, bran, burdock root, chia seeds, chicory, Chinese chives, cocoa, cottage cheese, dandelion greens, eggplant, flax seeds, fruit, garlic, green tea, honey, Jerusalem artichokes, jicama, leeks, legumes, lentils, onions, peas, plantains, potatoes, radishes, root vegetables, rye, sea vegetables, soybeans, spices and herbs, sweet potatoes, tomatoes, vegetables, and yams. Eat several servings of foods from this list each day.
You can also fill up on probiotic-rich foods:
- Yogurt, which typically contains several Lactobacillus species (such as Lactobacillus acidophilus, Lactobacillus thermophilus, and Lactobacillus bulgaricus), is a good choice. Kefir, another milk product, is even richer in probiotics than yogurt. Buttermilk and acidophilus milk also have plenty of probiotics. Among cheeses, gouda and cottage cheese are particularly rich in probiotics. If dairy doesn’t agree with you, look for an oat, soy, or nut-based yogurt.
- Try sauerkraut or kimchi. Look for an unpasteurized variety. Fermented foods naturally contain probiotics.
- Sour pickles (not cured with vinegar) are packed with probiotics, as are most olives.
- Miso soup—which contains fermented soybean paste—is rich in probiotics. There are over 150 species of microbes in it. So is tempeh, fermented soybean patty.
- Authentic sourdough bread (made from a yeast-containing culture) delivers plenty of probiotics—which the latest research shows can improve the microbiome even though they’ve been through the baking process.
- Unpasteurized beer and wine are also fermented foods. But pasteurization (common in mass-produced beers) kills the friendly bacteria.
- Raw honey contains up to 14 species of probiotic bacteria.
- Other foods that deliver probiotics include coffee, chocolate, coconut, and black tea. And don’t forget kombucha, a fermented, effervescent form of tea.
Slowly add more servings of probiotic-rich foods to your daily diet. If you introduce too many foods too fast, you may develop gas and bloating.
Cut back on ultra-processed foods, particularly those that contain sugar and white flour, which feed bad bacteria.
Despite all the research on probiotics and disease, researchers are cautious about recommending probiotic supplements for self-care. However, if you have one of the diseases or disorders that probiotics can help, taking a daily probiotic supplement might benefit you. (These conditions include the diseases and disorders discussed here as well as infections like cold and flu; skin problems like acne, eczema, and psoriasis; and genitourinary problems like vaginal infections and kidney stones.)