Before you were born, your gut was relatively sterile. Once you left the womb, you started collecting bacteria to form what is now your normal gut flora. By now, you have more than 400 species of bacteria living in your gastrointestinal tract, according to the World Health Organization. Support your normal flora by eating foods that contain good bacteria, or probiotics, which the WHO defines as live microorganisms that benefit your health when you consume them.
Good Bacteria and Immunity
Seventy percent of your immune system is in your gut, according to Johns Hopkins Medicine. Those good bacteria in your colon destroy toxins produced by bad bacteria and make compounds that benefit immunity, so ingesting good bacteria may help fortify your immune system. The Streptococcus thermophilus used to make yogurt, for example, prevents E. coli from taking up residence in your gut and causing infectious diarrhea, according to the authors of a 2005 study in "Nutrition in Clinical Practice."
Good Bacteria and Gastrointestinal Health
Consuming good bacteria also may improve the the health of your gut. Certain probiotic strains, such as Bifidobacterium infantis, may help move food through your digestive system and relieve the bloating and abdominal pain associated with irritable bowel syndrome, according to the American College of Gastroenterology. The National Dairy Council maintains that yogurt starter cultures, such as Lactobacillus bulgaricus and Streptococcus thermophilus, also reduce the symptoms of lactose intolerance associated with dairy products.
Fermented Dairy Products
Consume fermented dairy foods to strengthen your probiotic arsenal. Yogurt, kefir and some cheeses contain gut-friendly organisms such as Bifidus animalis and Bifidobacterium lactis. They also make good delivery vehicles because they protect the organisms from the acidic environment of your stomach. Look for the “Live Active Cultures” seal on refrigerated and frozen yogurt. Established by the National Yogurt Association, the seal indicates products that contain significant amounts of healthy bacteria.
Other Fermented Foods
Foods made from fermented soybeans and vegetables offer up more than just strong flavors. The lactic acid bacteria used to make miso, for example, produces Vitamin B12, according to the authors of a 2008 study in the "Journal of Industrial Microbiology and Biotechnology." Soy sauce, tempeh and natto are also sources of beneficial bacteria. Lactobacillus plantarum and Lactobacillus sakei, used to ferment vegetables to make kimchi, prevented foodborne illness in a 2011 study published in the "International Journal of Food Microbiology."
Feed Your Good Bacteria
Good bacteria have to eat, too. Undigested fiber serves as food for the microorganisms in your gut -- they ferment it to make compounds that promote a healthy gastrointestinal tract. Eat fruits, vegetables, beans, legumes and whole grains, which are excellent sources of indigestible fiber.
- Food and Agriculture Organization of the United Nations/World Health Organization Working Group on Drafting Guidelines for the Evaluation of Probiotics in Food
- Johns Hopkins Medicine: Whole-Person Gastroenterology
- American Gastroenterology Association: Probiotics: What They Are and What They Can Do for You
- Nutrition in Clinical Practice: Probiotics: A Practical Review of Their Role in Specific Clinical Scenarios
- American College of Gastroenterology: Probiotics for the Treatment of Adult Gastrointestinal Disorders
- National Dairy Council: Functional Dairy Foods: Making Healthy Eating Easier
- Journal of Industrial Microbiology and Biotechnology: Traditional Healthful Fermented Products of Japan
- International Journal of Food Microbiology: Functional Properties of Lactobacillus Strains Isolated from Kimchi
- Journal of the American Dietetic Association; Resistant Starch Intakes in the United States; M.M. Murphy, et al.
Amy Long Carrera is a registered dietitian in Los Angeles who has been writing since 2007 for such publications as The Insider, On the Other Side and Arthritis Today. She is a certified nutrition support clinician and her writing employs current research to provide evidence-based nutrition information. Carrera holds a master of science degree in nutrition from California State University, Northridge.