Probiotic bacteria, often called “friendly bacteria,” are living microorganisms similar to those found in the human digestive tract. They naturally occur in some foods and beverages, such as fermented cheese and certain types of yogurt, and can be produced separately as dietary supplements. Probiotic bacteria are also used in complementary and alternative medicine to aid with digestive disorders.
Several different types of food contain probiotic bacteria. Some occur naturally and others are added during manufacturing. Naturally occurring probiotic bacteria date back to ancient times, when they were found in cultured milk products and fermented foods. Other foods that may contain the friendly bacteria include miso, soy beverages, yogurt, and milk.
Élie Metchnikoff, a Russian immunologist, is credited with discovering the benefits of probiotic bacteria in modern times. He developed a theory that B. acidophilus, lactic-acid bacteria typically found in dairy products, could prolong life by preventing “fouling” in the large intestine. Spurred on by Metchnikoff’s research, other scientists began looking at different types of lactic-acid bacteria. One of those scientists, Henneberg, proposed using Lactobacillus acidophilus, found in the human intestinal tract, which went on to become popular throughout the world.
Numerous scientific studies have been performed to determine the effectiveness of probiotic bacteria in helping relieve disorders of the digestive system. Results from these studies indicate that probiotics are beneficial at treating diarrhea, particularly if it is caused by antibiotics. Antibiotics work by destroying bacteria, and they rarely discriminate between the good and the bad. Putting good bacteria back into the system may help alleviate the negative symptoms associated with antibiotic medications.
Fermenting food with probiotics has also shown to increase the folic acid content of that food. Folic acid, a B-complex vitamin, is an important nutrient, especially during pregnancy. It plays a role in preventing birth defects, including spina bifada, a condition that occurs when the spinal column does not close around the spinal cord. Folic acid may also play a role in keeping the heart healthy and preventing cancer-causing changes in the cells.
Although foods are considered the best source of probiotic bacteria because of the synergistic nature between the ingredients in the food and the bacteria, over-the-counter supplements are also available. Dietary supplements, however, may not be standardized and effects can differ from brand to brand. Less research has been performed on the long-term effects of these types of dietary substances versus the effects of probiotics found in food.
Side effects of probiotic bacteria are typically mild and may include gas or bloating. In rarer cases, patients with underlying medical conditions may develop an infection that needs to be treated with antibiotics. Overstimulation of the immune system or metabolic changes can also occur. Those considering using probiotics as an alternative medical treatment should consult with a physician first.