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Mayo Clinic Health Library

For a healthy gut, feed the good bugs

Updated: 06-07-2017

Right now you are covered in trillions of bacteria, both inside and outside your body. Ready to reach for the hand sanitizer? Hold on. While some of these bacteria lead to disease, others benefit your health. Your diet greatly affects which ones thrive.

Recent research is revealing the many ways certain bacteria and a balance of differing bacteria can impact your health. These bacteria are part of the human microbiome, along with fungi, viruses and archaea. They cover every inch of the body's surface area, including the scalp, the inside of the mouth, the lining of the esophagus and the back of the knee. Your body holds about the same number of bacteria as cells — around 30 to 50 trillion — with the gut microbiota hosting by far the most. (The microbe community in a specific part of the body is called a microbiota.)

The good bacteria in the gut microbiota have numerous roles including:

  • Metabolizing nutrients and drugs
  • Aiding the immune system to prevent pathogen invasion
  • Maintaining the structure and function of the gastrointestinal tract

However, the gut microbiota often harbors less helpful bacteria, too. Researchers have connected an imbalance in good and bad bacteria with disorders such as arthritis, irritable bowel disease, obesity, cancer and depression.

Age, genetics, diet, environment and lifestyle all appear to influence the kinds of bacteria that make up the microbiome. While you can't control all of those, your diet and lifestyle choices (smoking, drinking, exercise, and so on) give an advantage to one side or the other, especially over the long term. Research suggests that eating plants and whole grains help the good bacteria flourish by supplying complex carbohydrates that the human body can't digest — so they become bacteria food. Certain foods with active cultures, such as yogurt, kimchi and kombucha, can also add helpful bacteria to your system.

  • Try this: Focus on eating at least five servings of fruits and vegetables daily. Fruits and vegetables are not only highly nutritious but also contain complex carbohydrates to help good bacteria to thrive.
  • Research further shows that fat and sugar nourish bad bacteria, thereby increasing the prevalence of those bacteria that cause disease. In addition, studies suggest diets high in animal protein are correlated with a more unfavorable bacteria makeup.
  • To foster a healthy gut microbiota, limit processed foods in your diet, as these are often high in sugar and fat.
  • Try replacing animal sources of protein with plant sources of protein such as legumes, nuts, tofu and tempeh during the week.

So remember: Eating fruits and vegetables isn't just good for your health, it's also good for your microscopic companions.