Bacteria have earned an unfair reputation as disease-spreading "bugs." In reality, many health-promoting bacteria live in your body, where they support your immune system, ward off pathogens and suppress allergic reactions. When you take antibiotics or contract infections, these protective bacteria may be temporarily destroyed. Restoring healthy colonies of beneficial bacteria is one function of probiotics, living organisms that occur naturally in cultured foods and beverages. Natural sources of probiotics are not a substitute for medical treatment of digestive disorders, infections or allergies.
A cultured dairy product, yogurt boasts numerous bacterial flora, including the widely known Lactobacillus acidophilus. L. acidophilus can prevent gastrointestinal infections if taken regularly, reports the University of Maryland Medical Center. The lactic acid and other products of L. acidophilus inhibit the growth of pathogens that cause gastric disorders. L. acidophilus may also treat constipation, the symptoms of irritable bowel syndrome, urinary tract infections and vaginal infections. You can buy L. acidophilus in capsule or powder form, but yogurt offers calcium, protein and other nutrients in addition to probiotic microbes.
The tart taste of kefir, a fermented dairy beverage that originated in Central Asia, is similar to yogurt, but kefir has a different nutritional composition. In addition to bacteria that generate lactic acid, kefir contains beneficial yeasts that colonize the digestive tract and support natural immunity. If you are lactose-intolerant, drinking kefir may relieve symptoms such as diarrhea, gas and bloating. This cultured beverage contains lactase, an enzyme that helps you digest milk products. The easily digested proteins in kefir make it a healthy probiotic drink for infants, the elderly and people with compromised immune systems, according to an article published in a 2003 issue of the "Pakistan Journal of Nutrition."
You may be familiar with miso through the soup commonly served in Japanese restaurants, but you may not be aware of its probiotic properties. Made from fermented soybeans, the grain-like particles of this Japanese food are another source of L. acidophilus. In addition to encouraging healthy digestion and preventing gastrointestinal infections caused by organisms like H. pylori and C. difficile, L. acidophilus may relieve pollen allergies and help to lower cholesterol, according to the University of Maryland Medical Center. More clinical evidence is needed to verify these claims.
Tempeh consists of soybeans mixed with rice or millet, then formed into cakes and fermented. A versatile protein source, tempeh has a nutty flavor and can be blended with salads or stir-fries as a source of L. acidophilus and other lactic-acid-producing bacteria. Though tempeh is not as popular in the United States as tofu, the University of Michigan Health System includes this immunity-boosting soy product in its "Healing Foods" pyramid.
Even if you've always been put off by the smell of sauerkraut, kim chee, and other forms of fermented cabbage, you may enjoy their probiotic benefits. Used in pickling as well as fermentation, the lactic acid in sauerkraut can help digestion, while the antioxidants in cabbage support your immune system.