Q: What exactly are
”
probiotics
”
? I’ve heard they can help treat intestinal and other health
problems.
Q: What exactly are “probiotics”? I’ve heard they can help treat intestinal and other health problems.
A: The term probiotics (from pro and biota, meaning “for life”) refers to living bacteria that produce health benefits. Such helpful microorganisms live naturally in every healthy person’s digestive tract. They’re also found in foods fermented with bacteria, such as yogurt. A small but growing body of evidence suggests that you can treat and even prevent some illnesses with foods and supplements that contain probiotics.
More than 500 different types of bacteria live in your digestive tract, or gut. Most are helpful. They keep harmful bacteria in check, aid digestion and nutrient absorption, and contribute to immune function.
Disease, stress, a poor diet and certain medications can all deplete these beneficial bacteria. When that happens, other bacteria can get a foothold, causing intestinal woes such as diarrhea. Sometimes, unchecked bad bacteria can cause inflammation of the intestinal lining (a condition called colitis). That’s why it makes some sense to replenish your supply of “good” bacteria, particularly when your gut is under siege.
Since the mid-1990s, a host of studies have hinted that probiotic therapy may help the following conditions:
• Acute diarrhea: Bacteria known as Lactobacillus GG can shorten the course of infectious diarrhea in infants and children. One study found a combination of two different strains of bacteria added to infant formula reduced diarrhea rates by 24 percent.
• Antibiotic-associated diarrhea: Two large reviews suggest that probiotics lower antibiotic-associated diarrhea by 60 percent, when compared with a placebo.
• Inflammatory bowel disease: Several small studies suggest that certain probiotics may help people with ulcerative colitis stay in remission and prevent complications of surgery for the disease. They may also prevent relapses of Crohn’s disease.
• Lactose intolerance: Some people suffer from gas, bloating and diarrhea if they drink milk. Their bodies are short on lactase, an enzyme needed to break down lactose (milk sugar). More than 20 years ago, researchers showed that people with lactose intolerance had fewer symptoms if they ate yogurt instead of milk. The bacteria in yogurt produce lactase, which digests the lactose before it reaches the large intestine.
• Other gastrointestinal problems: Probiotics are also being studied for treating constipation, traveler’s diarrhea and H. pylori infection, which causes stomach ulcers and gastric cancer. No strains are entirely effective in treating irritable bowel syndrome. But some help relieve individual symptoms such as bloating, gas or diarrhea.
In women, the vagina and urinary tract can be thrown out of balance by a number of factors. These include antibiotics, spermicides and birth control pills.
Probiotic treatment that restores the balance of microorganisms may be helpful for such common female problems as bacterial vaginosis, yeast infection and urinary tract infection.
Many women eat yogurt or insert it into the vagina to treat recurring yeast infections, a folk remedy that has limited medical evidence to support it. Oral and vaginal use of Lactobacilli may help treat bacterial vaginosis. But so far, there isn’t enough evidence to recommend it over conventional approaches. Probiotic treatment of urinary tract infections is under study.
The recommended doses of probiotics range from 1 billion to 10 billion colony-forming units several days per week. Lactobacillus GG, marketed as Culturelle, is sold in capsule form. VSL #3, another popular brand, comes in packets of powder that you sprinkle on food. To get the benefits of probiotics in yogurt and other cultured products, make sure the label says the product contains “live” or “active” cultures.
There’s not much data on how long you should take probiotics for diarrhea. A daily supplement for one to two weeks is often recommended. Some people take probiotics as a routine prevention measure, based on suggestions that they help boost the immune system. But without further research, it’s hard to say if that practice actually keeps you healthier.
Probiotics are generally considered safe, since they’re already present in the body. However, in the United States most probiotics are sold as dietary supplements, which do not undergo the testing and approval process that drugs do. Health benefits are strain-specific, and not all strains are necessarily useful. You may want to consult a practitioner familiar with probiotics to discuss your options. As always, let your primary care provider know what you’re doing.
Submit questions to the Harvard Medical School Adviser at www.health.harvard.edu/adviser. Unfortunately, personal responses are not possible.
