Don’t freak out, but right now there are trillions of tiny bugs crawling all over and inside your body. But these aren’t the creepy crawlies that keep you up at night or give you a fright when spotted in a dusty corner. These “bugs” are part of your microbiome, a menagerie of mostly beneficial bacteria that scientists are now discovering can influence the functioning of everything from the immune system and gastrointestinal tract to the endocrine system and skin.

 We have long known that bacteria exist within our bodies in abundance. In fact, there are 10 times more bacterial cells in your body than there are human cells: We are fully functioning, symbiotic organisms, groomed from birth to coexist and thrive with help from the countless microbes that inhabit both the areas on our bodies directly exposed to the environment (like the skin) and the body parts that interact with the outside world, such as the gastrointestinal tract (GI) and nasal membranes.
It’s the bacteria in the GI tract that have garnered the most interest among researchers. There are a thousand distinct bacterial species living in the GI at any given time. As you grow, the great mishmash of bacteria in your gut settles into something of a checks-and-balances system. Troublemaker microbes are typically canceled out by beneficial ones like Bifidobacterium and Lactobacillus. Scientists aren’t sure exactly what any of those bugs really do, but they know we have a complex, dynamic relationship with them.

Sometimes, though, when your gut’s balance is tipped in the wrong direction (called “dysbiosis”), more insidious microbes begin to take over, prompting inflammation that can pave the way to diseases like type-1 or type-2 diabetes, obesity, or even neurological problems. Other disorders linked to GI tract microbial imbalances include inflammatory bowel disease, lupus, multiple sclerosis, psoriasis, rheumatoid arthritis, cancer, and cardiovascular disease. Dysbiosis triggers include poor diet, overprescription of antibiotics, or simply leading an overly sedentary lifestyle, according to a 2013 analysis in the journal Clinical Reviews in Allergy and Immunology.


To keep your microbiome in a harmonious equilibrium, it’s important to eat a diet that contains probiotics. “Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host,” says Mary Ellen Sanders, Ph.D., executive science officer at the International Scientific Association for Probiotics and Prebiotics.

“Probiotics are thought to play a role in preventing and treating certain diseases and infections such as irritable bowel syndrome [IBS], UTIs, vaginal infections, and more,” adds Alissa Rumsey, R.D., C.S.C.S., founder of Alissa Rumsey Nutrition and Wellness. “They may also reduce the risk of infections and illness.” You can find probiotics in foods like yogurt and kefir (look for the “live and active cultures” seal) and aged cheeses and other fermented foods like tempeh, miso, unpasteurized sauerkraut, and kombucha.