Most people have heard about probiotics, the good bugs that help our guts, even if they haven’t taken them. But they may not know that these good bacteria help more than just the stomach. How do they work, what can they be used for and who should use them?

“Probiotics are foods and supplements that contain microorganisms, which improve digestive and overall health,” says Ivy Branin, ND, a naturopathic physician in New York City.

The Food and Agriculture Organization of the United Nations (FAO) defines probiotics as "live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host."

Why would we want to consume live microorganisms? Branin explains that we need to maintain normal flora to prevent infections by pathogenic bacteria, to maintain the integrity of the lining of the digestive tract, and to digest food. Sometimes medications, diet, diseases, infections or the environment can upset the balance between the good and bad bacteria. Probiotics can help restore that harmony.

There are more than 400 bacterial species within a normal gastrointestinal tract. Small amounts are found in your stomach and small intestines, while the majority reside in your colon. These intestinal microflora aid in digestion, integrate vitamins and nutrients, metabolize some medications, support the functioning of the gut, and enhance the immune system.

When your immune system isn’t functioning optimally, you’re more likely to develop colds, flu, allergic reactions, and auto immune disorders like rheumatoid arthritis or Crohn’s disease. And when those gut microflora are disrupted, you may be more susceptible to a variety of disorders.

“Probiotics are especially beneficial for people who have frequently taken antibiotics, because beneficial bacteria in addition to pathogenic bacteria are killed off during antibiotic use,” says Branin.

Using probiotics can help prevent infection, decrease the duration of diarrhea associated with a variety of causes, decrease symptoms of irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and even improve lactose intolerance. They also keep the gastrointestinal tract healthy and can help manage autoimmune disorders associated with gut abnormalities like fibromyalgia, chronic fatigue syndrome and eczema.

However, people with compromised immune systems and serious infections like pancreatitis should check with their doctor before beginning a probiotic, as there can be conditions that make their use inadvisable, Branin cautions.

We can get probiotics in live culture dairy products such as yogurt, kefir and sour cream. In addition, fermented soy and vegetables such as sauerkraut, kimchi, tempeh and miso contain live cultures. You can drink fermented tea called kombucha.

However, the most clinically significant organisms are Lactobacillus acidophilus and casei, Saccharomyces boulardii and bifidobacteria. "Most commercial yogurts don’t contain those,” explains Branin.

Probiotic supplements vary in the types of bacteria and quantity. Different bacteria are more beneficial for certain conditions.

Lactobacillus acidophilus – These beneficial bacteria are good for treating and preventing ulcerative colitis, irritable bowel syndrome, canker sores, eczema, lactose intolerance and the prevention of respiratory infections.

Acidophilus is also good for people on antibiotics. Taking a supplement with at least 15-20 billion organisms of acidophilus a day can maintain normal flora to prevent antibiotic-induced diarrhea, yeast infections and urinary tract infections. These may be found in yogurt, kimchi, miso, sauerkraut and kefir in addition to supplements.

Bifidobacteria – Another strain that’s helpful when treating ulcerative colitis and irritable bowel syndrome (IBS). This strain is also associated with reducing dental cavities and improving low LDL (good) cholesterol levels.

Saccharomyces boulardii — Good for patients with Crohn’s disease, Clostridium difficile (commonly called C. diff.), a bacterium affecting adults in hospitals and long-term care facilities, and to reduce side effects of treatment for Helicobacter pylori, a stomach bacteria thought to be responsible for ulcers. It’s also used for preventing antibiotic-induced diarrhea, and in treating acne. May be found in kefir and kombucha tea.

Streptococcus thermophilus - Effective in the prevention of lactose intolerance. May be found in kimchi, kefir and sauerkraut.

In addition, tempeh may contain two molds, Rhizopus oryzae or Rhizopus oligosporus, and miso contains a variety of probiotics including Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Pediococcus acidilactici, Pediococcus pentosaceus, Lactobacillus plantarum and Weissella confusa. Branin recommends Pharmax HLC High Potency and Intensive. She also likes Flora Udo's Choice probiotics.

“Most people should be getting about 10 billion organisms a day of Lactobacillius acidophilus and bifidobacteria,” she says.

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