Probiotics are live microorganisms used for their beneficial health effects to the host. These microorganisms are non-pathogenic bacteria (small, single-celled organisms which do not promote or cause disease), and one yeast, Saccharomyces. Probiotics are typically used to help maintain a sufficient microflora (population of bacteria) in the digestive system, and to help prevent or treat gastrointestinal disorders. Digestive system microflora are also known as gut flora.
Probiotics are considered ‘‘friendly germs,’’ due to benefits to the colon and the immune system. The word probiotic is a compound of a Latin and a Greek word, and it means ‘‘favorable to life.’’ Probiotics is also sometimes used to refer to a form of nutritional therapy based on eating probiotic foods and dietary supplements.
Although probiotic supplements have also been used with farm animals, most are produced for human consumption. Often, these come in the form of dairy products containing two types of bacteria—those in the genus Lactobacillus and those in the genus Bifidobacteria—as supplements in pills or capsules, or as ingredients in face creams and other cosmetic products.
In addition to probiotics, there are prebiotics. Prebiotics are ingredients in food. Although they are not digestible by humans, they do serve as food for probiotics and therefore support their viability and enhance their survivability. Prebiotics are also known as soluble fiber.
Probiotic foods and dietary supplements have been recommended as treatments for a variety of diseases and disorders, ranging from problems confined to the digestive tract to general health issues. Intestinal complaints Probiotics have been used to manage a variety of intestinal disorders, including:
- pseudomembranous colitis, a potentially life-threatening inflammation of the colon caused by an overgrowth of the bacterium Clostridium difficile as a result of the patient’s having taken antibiotics that cause profuse watery diarrhea, cramps, and low-grade fever.
- so-called ‘‘traveler’s diarrhea’’
- acute nonbacterial diarrhea
- rotaviral diarrhea
- irritable bowel syndrome (IBS)
- bacterial overgrowth in the small bowel by organisms such as Helicobacter pylori, which is implicated in gastric ulcers
Researchers at the Yale University School of Medicine published a study detailing the consensus opinion of experts. That study listed probiotics as being most effective for treating and/or preventing childhood diarrhea, ulcerative colitis (a form of inflammatory bowel disease), necrotizing enterocolitis (death of tissue in the colon, mainly affecting premature babies), antibiotic-associated diarrhea, and infectious diarrhea (gastroenteritis). The study also noted that, although the scientific evidence was less clear, probiotics may also be helpful in treating and/or preventing symptoms of irritable bowel syndrome, certain bacteria-caused diarrhea, and Crohn’s disease.
Additional research has been conducted into other potential benefits of probiotics. For instance, a study published in PLOS One reported that probiotics ‘‘could be applicable to modulate antibodymediated autoimmune diseases, including myasthenia gravis.’’ Myasthenia gravis is a neuromuscular disease with symptoms including weakness and fatigue.
Another study suggests that probiotics may lower the risk of common childhood illnesses such as ear infections, strep throat, and colds.
- Lifestyle-related disorders
Some supporters of probiotics go beyond applications limited to treatment of intestinal disorders. In keeping with the theory of autointoxication, they maintain that probiotics are effective in treating a wide range of chronic and acute illnesses thought to result from a condition called intestinal dysbiosis, or poor intestinal health quality due to toxic buildup, putrefaction, and leaky gut syndrome. Intestinal dysbiosis is defined as an imbalance among the various microorganisms in the digestive tract. This imbalance is attributed to a combination of Western high-protein diets, stress, environmental pollution, and allopathic medications. Putrefaction is believed to result from a low fiber diet, chronic constipation or sluggish colon, and poor food, which all combine and lead to increased gut fermentation. Leaky gut syndrome is the term used to suggest that the effect of these toxins on the intestinal cell walls is damaging to intestinal integrity, and as a result, large molecules of relatively undigested food and toxins cross the intestinal membrane into the bloodstream.
Some alternative practitioners maintain that the following diseases and disorders are directly related to intestinal dysbiosis or may also be beneficially treated with probiotics:
- mental health problems
- chronic fatigue syndrome
- muscular soreness and stiffness
- autoimmune disorders, including lupus, rheumatoid arthritis, ankylosing spondylitis, enteric arthritis, and Reiter’s syndrome (by immune stimulation and repair of the leaking gut)
- lactose intolerance (by increasing the presence of lactase)
- infectious diseases
- high blood pressure (research has demonstrated a systolic blood pressure decrease of 10–20 mm Hg with the use of a fermented milk product)
- high cholesterol
- cancer (by decreasing exposure to gene-altering substances)
- menopausal problems in women (by improving the liver’s ability to detoxify and eliminate hormonal metabolites)
- vaginosis, once thought to be relatively benign, but now implicated in easier transmission of sexual diseases, pelvic inflammatory disease, and pregnancyrelated complications (improved by reducing vaginal pH, which inhibits the growth of unfavorable bacteria)
- allergies and asthma (a double-blind placebo-controlled study demonstrated a 50% drop in children followed up to two years of age)
- kidney stones (by inhibiting the absorption of oxalate from the intestines)
More specifically, probiotic foods and dietary supplements are claimed to counteract intestinal dysbiosis in the following ways:
- production of vitamins. Friendly bacteria are said to manufacture vitamin B3, vitamin B6, and folic acid.
- anti-tumor and anti-cancer activity
- suppression of pathogenic microorganisms in favor of the non-pathogenic
- relief of anxiety symptoms through indirect detoxification
- protection against radiation and other environmental toxins
- support of the immune system, by reducing immune load
- recirculation of female hormones in the bloodstream by a cleaner liver and cleaner blood, thus maintaining higher levels of estrogen inmenopausal women
- maintenance of smooth bowel functioning
Due to a lack of scientific support for these uses of probiotics as well as the potential, however slight, for negative side effects, patients should consult with their doctor before beginning a probiotic regimen.
Probiotics is a nutrition-based therapy and relies primarily on the addition of foods or supplements containing friendly bacteria to the diet. Some recommended foods are ordinary grocery store items that involve fermentation in their production. These include miso, pickles, sauerkraut, and fermented dairy products such as yogurt and kefir.
Probiotic dietary supplements are over-the-counter (OTC) preparations available at grocery and other stores. Probiotics are also available in hand creams and other items.
Because probiotic products may include some ordinary dairy and grocery items, most people who use them do not think of them as medications and see no need to consult a health professional. Persons who are taking prescription medications and persons with compromised immune status, however, are advised to consult their doctors before using probiotic dietary supplements. These products often influence the bulk and frequency of bowel movements, thus increasing the elimination rate of some medications and necessitating a dose adjustment.
Some practitioners of nutritional therapies recommend cleansing the lower digestive tract with an enema or colonic treatment before beginning a course of probiotic supplements. Conversely, use of probiotics may be particularly recommended following colonic therapy, just as it is following antibiotic therapy.
Although the bacteria in probiotic supplements are human-friendly, some individuals may have food allergies or a digestive tract that is sensitive to miso, other fermented foods, or the milk powder that may be in some products. Vegetarians or people who cannot digest milk-based products may prefer probiotic supplements with a rice base.
The administration the probiotic Saccharomyces boulardii can be associated with fungemia, which is the presence of fungi in the blood, but this typically causes no adverse effects.
Research published in Therapeutic Advances in Gastroenterology, for instance, found no adverse effects in the clinical trials it reviewed. However, the authors advised caution for those patients with risk factors that might make them susceptible to such effects.
Probiotics are generally considered safe. One commonly reported side effect is intestinal gas, and some people report headaches, diarrhea, bloating, or constipation. These side effects may last for several days. Practitioners recommend lowering the supplement dosage to reduce the side effects, or pretreating with colonic therapy, or with stool softeners and fiber as tolerated or advised by a healthcare professional.
Research and general acceptance
Probiotics are readily available in stores and in various products, and people use them to treat and prevent a wide array of medical conditions. Scientific research as of 2013, however, has still not verified the benefits of probiotics for many of these uses.