With the growing popularity of probiotic foods and supplements, the definition of probiotic bacteria has expanded. The popular definition of probiotic bacteria might include any live, microscopic organism that may promote health or support your immune system. In her 2008 article published in "Clinical Infectious Diseases," food microbiologist Mary Ellen Sanders, Ph.D. stresses the need to limit the term "probiotic" to products that have clinically documented health benefits for humans, and to identify probiotic bacteria by their strains and effects.
Functions
A probiotic microorganism must be a live microbe that benefits the health of its human host, according to the definition developed by the World Health Organization and the Food and Agriculture Association of the United Nations. Bacteria are living, single-celled microorganisms. Probiotic bacteria dwell in your mouth, digestive tract, reproductive passages and on your skin. These bacteria fight infection by releasing metabolic by-products that discourage pathogens, or harmful microbes, from invading and causing gastric, urinary or vaginal infections. Probiotic bacteria also produce enzymes that aid digestion, helping you metabolize nutrients and minimizing side effects like bloating, gas or diarrhea.
Significance
If you have ever taken antibiotic medications to fight an infection, you may have had diarrhea, vaginitis or oral thrush while you were taking the antibiotics. Secondary infections occur when the probiotic bacteria that live in your body are destroyed along with the pathogenic microbes that make you sick. Cultured and fermented foods contain probiotic bacteria that can replace your natural bacterial flora and reproduce their benefits. Recent research indicates that probiotic bacteria may help lower cholesterol and relieve respiratory allergies, but there is not enough clinical evidence to verify these effects.
Sources
The same process that creates fermented or pickled foods also supports healthy digestion and immunity. The metabolic activities of bacteria like Lactobacillus and Bifidobacterium species release compounds that allow these processes to take place. Cultured foods like yogurt, kefir and cheese or fermented soy products like tofu and tempeh contain probiotic bacteria. These probiotic bacteria are also available as dietary supplements in capsule, powder or liquid form. The therapeutic properties of probiotic foods and supplements have not been confirmed by clinical investigation.
Identification
Bacteria are identified by their genus, species and strain. The packaging on probiotic products often does not specify the taxonomic name of the bacteria that the product contains. Using the umbrella term "probiotic" does not identify the properties or recommended uses of the many bacterial strains that are available in foods, beverages and dietary supplements. Dr. Sanders in her "Clinical Infectious Diseases" article emphasizes the need to narrow the definition of probiotic bacteria to include the health benefits and therapeutic uses of each strain.
Consumer Protection
Distinguishing the benefits of specific bacterial strains would help you make informed decisions about which probiotic products to buy, says Sanders. The term "probiotic" should be limited to foods or supplements that have met clinical standards of effectiveness at preventing infection, promoting healthy metabolism or supporting the immune system. The FDA has not approved the use of probiotic products for medicinal purposes.
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