Dear Doctor Column, July 10, 2006
What are probiotics and do they offer any health benefits?
Answer:
Probiotics are living microorganisms — bacteria or yeast — that can potentially help the digestive system maintain or restore a healthy bacterial balance. Probiotics are usually taken orally and sold as foods and dietary supplements. If you eat yogurt, you’ve probably already had a dose of probiotics. Many yogurts contain live beneficial bacteria, most often lactic acid bacteria such as Lactobacillus acidophilus.
Bacteria have a reputation for causing disease, but not all these microorganisms are harmful. More than a trillion naturally occurring microorganisms from about 400 species of bacteria form colonies in a normal human intestinal tract — most don’t cause illness, but aid digestion, provide protection against harmful bacteria and allergens, and may help boost immune system function.
When the balance between “good” and “bad” gut bacteria, or flora, is thrown out of whack, the imbalance may contribute to symptoms of gastrointestinal disorders, such as irritable bowel syndrome (IBS) and perhaps ulcerative colitis. Research also has linked microbial imbalances in the gut with acute infectious diarrhea and pouchitis, a complication of surgery for ulcerative colitis where the remaining pouch of the colon becomes infected.
Gastrointestinal illnesses, stress, excessive alcohol use, and antibiotics, which kill intestinal bacteria regardless of their “good” or “bad” status, are some factors that deplete beneficial gut flora, upsetting the normal balance. Probiotics form temporary colonies of beneficial bacteria, and may help with some of the same functions performed by natural gut bacteria and allow natural flora time to regrow.
Probiotics products can contain many different types of microorganisms and not all are helpful for the same condition. Microorganisms from the Lactobacillus and Bifidobacterium genera are the most commonly used bacteria in probiotic products. Evidence from clinical trials, for example, shows that Lactobacillus GG — a species of Lactobacillus — can reduce bouts of infectious diarrhea by about a day in infants and children, but not in adults.
Research has shown probiotic therapy also may be useful for difficult-to-treat conditions such as IBS and ulcerative colitis. A recent study published in the scientific journal Gastroenterology found Bifidobacterium infantis eased the abdominal pain, bloating, and constipation associated with IBS.
In another study, published in the American Journal of Gastroenterology, a highly concentrated probiotic cocktail combining eight strains of beneficial bacteria induced remission or reduced symptoms in some people with ulcerative colitis. Study participants took the cocktail, which included strains of Lactobacillus, Bifidobacterium, and Streptococcus, once a day for 6 weeks along with their regular medications: 53% experienced remission, while 24% had a significant decrease in the painful symptoms of the disease; 9% did not respond; and 9% grew worse. The 32 participants who completed the study had no significant side effects from the mixture. An ongoing placebo-controlled trial will help determine if this concentrated mixture actually proves useful for ulcerative colitis.
Some preliminary research also suggests probiotics may be useful for treating urinary and vaginal infections in women and allergies, lactose intolerance, and respiratory infections in children. In addition, lab and animal studies have shown probiotics may help protect against intestinal cancers. The scientific community is showing an interest in probiotics for many conditions, but more research is needed to clarify the microorganisms’ therapeutic role.
Foods and dietary supplements laced with probiotics already are making an impact on grocery and health food store shelves, and labels listing different bacterial strains and the conditions which they allegedly can help, can confuse consumers. Unfortunately, there are no established dosages for different conditions. Probiotics are measured in colony forming units (CFUs), and most research suggests you need a daily dose of at least 1 billion CFUs to reap significant health benefits. The good news is most probiotics products offer a much larger dose — a recent Consumer Reports review of probiotic products found yogurts and yogurt drinks containing probiotics (and not all yogurt does — you have to read the label) offered between 15 and 155 billion CFUs per servings. Supplements, which usually come in capsule or powder form, provided between 20 and 70 billion CFUS per daily dose.
Consumer Reports noted that some labels of products evaluated were incomplete. Some yogurts listed the types of probiotics in the products, but not their specific amounts. Supplements, which are made with dried bacteria (in this state, microorganisms are still alive, but dormant), tended to not be as potent as the labels claimed: most had about 20% of the CFUs the label said were present at the time of manufacture. Check the product label for the manufactured date and expected shelf life — some probiotic products should be stored in the refrigerator to maintain potency.
Probiotics are most often sold as food or dietary supplements and are not subject to the strict regulation governing pharmaceuticals. This gives manufacturers some latitude to make claims about health benefits of their products, but there is no guarantee the strain you buy will be effective for your health condition.
If you suffer from a gastrointestinal illness and are considering adding a probiotic to your therapeutic regimen, talk to your doctor first. Your physician can help you choose among the many strains of probiotics and explain how to best take the product. You should also consult your physician before beginning a probiotic regimen if you’re pregnant, breastfeeding, have a weakened immune system, or are recovering from surgery or a serious illness.
If you’re healthy and want to try a probiotic to maintain your gastrointestinal health or for the possible boost to your immune system, stick to well-studied types, such as strains from the Lactobacillus and Bifidobacterium genera. Eating yogurt with live bacteria is a relatively inexpensive way to give probiotics a try. This also can help you meet USDA dietary guidelines, which recommend three servings of low-fat dairy products a day.
For more information about probiotics, visit www.usprobitoics.org. The site is sponsored by the California Dairy Research Foundation, which has a commercial interest in probiotics, but contains useful information about specific strains, research, and probiotic products.