The gastrointestinal (GI) tract starts in the mouth and includes the long, twisting series of intestines. Once thought to be responsible for simply digesting food—now a growing body of research suggests the “gut” (stomach and intestines) is the headquarters for overall health.

How do gut bacteria affect us?

The gut houses hundreds of trillions of live microorganisms including probiotics or “good bacteria.” When the gut is colonized with plenty of probiotics, it sets the stage for:

  • Gut Health: Probiotics promote normal GI function, including regularity and normal stool consistency, reduced risk of Irritable Bowel Disease, and decreased symptoms of lactose intolerance. They may also decrease the likelihood of other food allergies or sensitivities.
  • Neurological Health: A healthy gut may lead to fewer headaches and migraines.
  • Mental Health: The gut is sometimes known as the “second brain”—and for good reason. The enteric nervous system, housed in the gut, has more neurons than the spinal column and central nervous system. In fact, most of the fibers of the vagus nerve are dedicated to communication between the gut and brain, hence those “gut feelings” or “butterflies in your stomach.” Additionally, gut flora produces neurotransmitters like serotonin (thought to be a contributor to feelings of well-being and happiness) and dopamine, which may decrease the risk of anxiety and depression.
  • Bone Health: Gut bacteria can help to improve bone mineral density.
  • Immune Health: Probiotics comprise more than 75% of the immune system. They protect the body from infection by fighting harmful substances that enter and facilitating their elimination. 
  • Decreased Inflammation: Probiotics can help reduce symptoms of rheumatoid arthritis.
  • Production of vitamins B and K
  • Blood Sugar Control
  • Heart Health

How can we impact gut bacteria?

The way we care for our bodies and the foods we consume have profound effects on gut bacteria. The beginning of the GI tract starts when we put food in our mouth. Cultivate good gut bacteria by:

Munching on prebiotics or fermentable fibers

Fermentable fibers and prebiotics are the foods gut bacteria need to maintain and grow their population. Munching on produce like asparagus, spinach, bananas, berries, onions, garlic, and leeks provides food for probiotics to thrive!

Getting friendly with fermented foods

Popular fermented foods include yogurt, kefir, kombucha, pickles, sauerkraut, miso, and tempeh. Incorporate these items regularly to enjoy the maximum benefits of the colonization of good bacteria.

Partaking of polyphenols

Polyphenols are phytochemicals that play a role in maintaining health and wellness in many ways, including acting as prebiotics. By eating a variety of brightly colored produce, spices, berries, coffee, and tea, you can ensure an increase in the population of beneficial bacteria in your gut.

Verifying your vitamin D status

In addition to bone health, vitamin D plays an important role in regulating the gut biome and immune system. Low vitamin D has been linked to increased autoimmune disease, allergies, infections, and other immune conditions. If your vitamin D is low, talk to your registered dietitian or doctor about supplementing with vitamin D3.

Exercising regularly

But remember: Exercise without adequate recovery, rest, food, and sleep can negatively impact gut flora.

Probiotics: Should I supplement?

If you’re healthy with no digestive complaints or immune problems, supplemental probiotics are unlikely to change your gut composition. 

If you’re doing all you can to use food as preventive medicine but still have concerns, consider talking to your doctor or registered dietitian about a probiotic supplement.

Blair Mize, MS, RDN, CSSD, LDN is co-owner of Memphis Nutrition Group, a nutrition & lifestyle counseling practice operated by registered & licensed dietitians/nutritionists. Memphis Nutrition Group believes in a non-diet approach that promotes overall health and optimal performance without compromising the enjoyment of food. For more information call Memphis Nutrition Group at 901.343.6146 or visit