Probiotics

4 TUFTS UNIVERSITY HEALTH & NUTRITION LETTER <www.tuftshealthletter.com> : NOVEMBER 2011

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Though “probiotics” have only recently passed the 8 million mark in Google hits, these “good bacte- ria” have been touted for their health benefits in many cultures for more than a century. An early 20th-century scien- tist, Russian biologist and Nobel Prize winner Elie Metchnikoff, first studied them after noticing that Bulgarians and Russians lived exceptionally long lives on diets including fermented dairy.

In the late 20th and early 21st cen- tury, interest in probiotics has boomed. From 1994 to 2003, US sales of prio- botic supplements nearly tripled. Food products containing probiotics have proliferated throughout the supermar- ket, including yogurt, fermented and unfermented milk, miso, tempeh, juices and soy beverages. Some of these foods get their “good bacteria” naturally, while others have the bacteria added in processing.

It’s important to keep in mind that, whether probiotics come in pill form or added to foods, they are regulated as foods, not medicines. As a result, when probiotic health claims have gone too far out on a limb, the manufacturers usually run afoul of the Federal Trade Commis- sion, which regulates false advertising, not the Food and Drug Administration.

So what should you make of these claims? Are probiotics right for you?

Friendly Bacteria

Though “bacteria” sounds like some-thing to stay far away from, the human body relies on “friendly” bacteria for healthy operation. The human gastrointestinal tract alone contains more than 400 different bacte- rial species. They work to maintain a healthy gut lining; we depend on them to produce vitamins and to suppress bad bacteria. They’re also used to break down food and produce the lactase en- zyme necessary to digest milk. (People who are lactose intolerant are deficient in this enzyme.)

Probiotics, according to the World

Health Organization, are “live micro- organisms, which, when administered in adequate amounts, confer a health benefit on the host.” There are four main families of probiotics: Lactobacil- lus and Bifidobacterium provide the most commonly used “good bacteria,” while others belong to the Saccharo- myces (actually yeasts, a different type of microorganism) and Streptococcus groups. Despite the scary associations with the term “Streptococcus,” a form of that bacteria—Streptococcus ther- mophilus—was the original probiotic, a yogurt starter popularized by Metch- nikoff in a book on longevity research, The Prolongation of Life.

Within each family are individual strains of microorganisms—the names you might see when looking on the back of a yogurt cup, for instance. Among the more common are Lactobacillus acidophilus, Bifidobacterium bifidum and Lactobacillus reuteri. Strains of Lactobacillus and Bifidobacterium have especially been highlighted in studies as therapeutic for various gastrointestinal conditions. Keep in mind, however, that benefits found from one species or strain of probiotics do not necessarily hold true for others, or even for different prepara- tions of the same species or strain.

Do They Work?

Some probiotics work to protect the body from unwanted invaders by colonizing and reproducing. These good bacteria are normally present in a healthy digestive tract, but some- times, there’s an imbalance that leads to gastrointestinal problems. Taking antibiotics can also deplete your body’s good bacteria while killing bad micro- organisms.

According to the federal govern- ment’s National Center for Comple- mentary and Alternative Medicine (NCCAM), “There is limited evidence supporting some uses of probiotics. Much more scientific knowledge is needed about probiotics, including

about their safety and appropriate use.” Nonetheless, a number of studies,

especially over the past decade, have suggested possible health benefits for probiotics. These have shown positive results not only for gastrointestinal con- ditions such as diarrhea, irritable bowel syndrome (IBS) and ulcerative colitis, but also with bacterial vaginosis. Other conditions have also been known to benefit from probiotics, such as Crohn’s disease and chronic yeast infections.

Diarrhea: A 2010 review of the scientific evidence by the international Cochrane Collaborative concluded that probiotic bacteria help reduce the length of time people suffer from diar- rhea. Patients given probiotics along with rehydration fluids reduced the duration of their diarrhea by one day compared to those not given probiotics, and were 59% less likely to suffer diar- rhea lasting four or more days.

Irritable bowel syndrome: A 2001 randomized, double-blind clinical trial focused on the effect of Bifidobacterium on IBS. Out of 122 patients tested, 62 received a placebo and 60 received the probiotic once a day for four weeks. Patients rated their intestinal discom- fort and IBS symptoms on a seven- point scale. Those who received the probiotic had their scores drop by 0.88 points, while those in the placebo group dropped only 0.16 points. In the pro- biotic group, 47% of patients reported “adequate relief,” compared to only 11% in the placebo group. Overall, the probiotic significantly improved pain, bloating and bowel urgency.

Ulcerative colitis: A 2004 study looked at the effect of using VSL-3, a commercial probiotic combining eight strains of bacteria, plus a mild dose of balsalazide, a drug used to treat ulcer- ative colitis, compared to the drug on its own in a higher dose. Three groups were studied: one with a combination of VSL-3 and balsalazide, one with bal- salazide alone, and one with mesalazine (another drug used to treat ulcerative colitis) alone. The results showed that the first group was “significantly superior” in obtaining remission; 24 of 30 patients enrolled in the probiotic groups were in remission by the end of the 12-month study.

Are Probiotics Right for You? Weighing the evidence on how good for you these “good bacteria” really are.

NOVEMBER 2011 : TUFTS UNIVERSITY HEALTH & NUTRITION LETTER 5

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A condition in women where the normal balance of bacteria in the vagina is disrupted, bacterial vaginosis (BV) is the most prevalent vaginal disorder in adults across the world. A 2010 Italian study looked at the proposed treatment of BV with a strain of the probiotic Lacto- bacillus, seeking to lower vaginal pH (more acidic). The study of 40 patients found that after 12 months of treat- ment, 24 had the desired pH and after 24 months, 32 had successfully lowered pH. As the pH lowered, the symptoms of BV were likewise reduced.

Which Should I Take?

If you think probiotics might be right for you, Robert M. Russell, MD, a gastroenterologist and emeritus profes- sor in Tufts’ Friedman School, suggests looking for the probiotic that has been researched the most for the condition you’re concerned about. For instance, a 2010 study in Poland concluded that, for adults with constipation, their problems are best treated with Bifidobacterium or Lactobacillus strains. The probiotic lactobacillus GG, discovered at Tufts in 1985 by Sherwood H. Gorbach, MD, and Barry R. Goldin, PhD, has also been thoroughly studied and proven to treat and prevent diarrhea.

The most important thing to look for, according to Dr. Russell, is that the bac- teria you’re ingesting is live. He explains that live bacteria-producing enzymes do different things metabolically in the intestines that dead bacteria simply can- not do. If the label doesn’t specifically say “live,” he advises not getting the product at all. It should also have a high bacte- rial count, typically labeled as “colony forming units” or CFU; look for at least 5-10 billion per serving. Keep probiotic products in the refrigerator to help the bacteria remain live.

Also, don’t necessarily jump to grab a bunch of yogurts just because they’re an easy way to get those friendly bacte- ria. Stephen Wangen, MD, chief medi- cal officer at the IBS Treatment Center in Seattle, warns that for those people who have a dairy allergy or intoler- ance, “the consumption of yogurt, even brands with high probiotic bacteria content, is inadvisable.”

What About Activia?

Perhaps the best-known probiotic product on supermarket shelves today is Activia, a yogurt made by Dannon that’s advertised as an aid to regularity and a healthier gastrointesti- nal tract. Activia has a high content of “Bifidus regularis,” a probiotic whose name was coined by Dannon, which advertises that Bifidus regularis is uniquely strong enough to survive the digestion process.

In late 2010, however, the Federal Trade Commission imposed strict new limits on Dannon probiotic yogurt prod- ucts as part of a $21 million settlement of an investigation into the company’s marketing. The agreement with the FTC states that Activia can claim only to “relieve temporary irregularity or help with slow intestinal transit time” if it also states that three daily servings are required for this benefit. And Dannon, which has marketed its drinkable yogurt DanActiv as an immune-system booster, must not make cold- or flu-fighting claims without FDA approval.

(Since then, however, a Cochrane Review concluded that probiotics were associated with a 12% reduction in up- per respiratory tract infections.)

If you’re considering trying Activia, Dr. Russell suggests it’s important to consider what regulation means to you. He explains that Activia ads are talking about the “prevention or treatment of constipation that’s not due to an obstructive disease, but rather, what we call functional constipation.” Dannon

advertises that the yogurt should be consumed “daily for two weeks as part of a balanced diet and healthy life- style.” Dr. Russell suggests that those with functional constipation might indeed benefit, but they should give it about a month before deciding if it’s working or not.

So far, the research funded by Dannon itself has been promising. But an independent Dutch study in 2008 reported that 248 out of 267 sub- jects reported “no significant effect of Activia... on the frequency, quantity or consistency of stools.”

What’s Next?

The jury’s still out on most hoped-for benefits of probiotics. But scientific research continues to probe these friendly bacteria for a wide variety of health effects, including those beyond the gastrointestinal tract. According to a 2005 conference report by NCCAM and the American Society for Micro- biology, other areas in which there is some encouraging evidence include reducing recurrence of bladder cancer and preventing and managing eczema in children. Researchers at Tufts Medi- cal Center are studying probiotics for treating an antibiotic-resistant type of bacteria that afflicts people who are hospitalized, live in nursing homes, or have weakened immune systems.

Given the long history of some probiotics, we know that these friendly bacteria are generally safe and that any side effects tend to be mild, such as gas or bloating. NCCAM cautions, however, that probiotics’ safety has not been thoroughly studied scientifically. More information is especially needed on how safe they are for young chil- dren, elderly people, and people with compromised immune systems.

As with any supplement or alterna- tive treatment, if you’re thinking about using a probiotic product, consult your health care provider first. Probiotics should not be used in place of conven- tional medical care or to delay seeking that care.—Jordana Kozupsky

TO LEARN MORE: “An Introduction to Probiotics,” <nccam.nih.gov/health/probiotics/introduction. htm?nav=cd>. X

Pro- or Pre-? Don’t confuse probiotics with prebiot- ics, which are often touted as offering similar benefits. “Prebiotics” aren’t actually microorganisms at all, but are non-digestible carbohydrates found in foods such as apples, onions, asparagus, bananas, sauerkraut and miso, as well as in extracts in supplement form. They are believed to improve the bal- ance of good bacteria in the digestive tract. Other possible benefits range from strength- ening the immune system to reducing the risk of high blood pressure to helping prevent colon cancer. These claims have yet to be verified by rigorous scientific trials, however.

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