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Probiotics: Research is Promising, But Few Products Can Be Trusted

Posted by medconsumers on January 1, 2006

Many people eat yogurt to protect themselves from antibiotics-induced diarrhea. Others swallow probiotic supplements for the same reason. Either way, the idea is to consume “good” bacteria in order to overcome the tendency of antibiotics to kill good, as well as harmful, bacteria in the gut, throat, and vagina. The public has caught on to the importance of eating microbe-containing foods, especially yogurt, as a way to prevent illness, such as traveler’s diarrhea, and as a way to maintain health. Now many yogurt containers proclaim the presence of “live active cultures,” and it is common to see probiotic capsules side by side with vitamins on the shelves of pharmacies and health food stores. Unfortunately, consumers may be wasting money because most of these products are untested and unproven to contain the necessary amounts of live microorganisms.

Consumer Reports

The problem was highlighted last year in the aftermath of a July 2005 Consumer Reports article featuring probiotics. It described several exciting areas of preliminary research that indicate probiotics could be beneficial to people with digestive disorders like irritable bowel syndrome and food allergies like atopic eczema. Other studies have suggested that probiotics may prevent respiratory infections, urinary tract infections, and precancerous changes that commonly occur in the large intestine. Such studies, however, prove only that one particular microorganism or a specific combination of microorganisms can provide this benefit. Unfortunately, some companies post these research findings on their Web sites implying that their untested products confer the same benefits.

As with all subjects taken on by Consumer Reports, the article ended with a list of products that passed the test-in this case, a list of yogurts, yogurt drinks, and supplements purportedly proven to contain the appropriate amounts of probiotics. But doubts were raised by Mary Ellen Sanders, PhD, president of the International Scientific Association for Probiotics and Prebiotics, in a letter to Consumer Reports (posted on

She objected to the article’s conclusion that 18 supplements and nine yogurt products actually contain one billion probiotic units, or colony forming units, the minimum needed for any meaningful health benefit, according to most researchers in this field. Furthermore, just having the right viable count doesn’t mean the product has been shown in a well-designed study to provide a health benefit.

While Consumer Reports was congratulated by Dr. Sanders for highlighting the potential value of consuming the right types of live bacteria and the importance of the dose delivered per serving, its testing methods were questioned. Dr. Sanders’s letter stated that many yogurts and probiotic supplements contain more than one type of bacterium and reporting the total may be misleading to consumers.

Consumer Reports had instructed readers “to pick a product with at least one billion probiotics units,” but that is actually the minimum for each strain of live bacterium in a product. Moreover, the magazine provided only sketchy information about the microbiological methods used to reach their conclusions about the recommended products. Unfortunately, this letter to the editor was not printed by Consumer Reports.

In a telephone interview, Dr. Sanders explained her frustrations with the products on the market that bill themselves as probiotics and/or carry the Live & Active Cultures seal of the National Yogurt Association (NYA). “The problem, in short, is this: with current labeling practices, consumers have no way of knowing if products contain the right number of efficacious probiotic strains. Even if the types are listed on the label, the names used may be inaccurate and the numbers may not sufficient or be what is claimed.”

In an effort to rectify the matter, Dr. Sanders met with officials at the U.S. Pharmacopeia (USP) in May, 2005 to see whether this public standards-setting authority would set the standards for probiotics. “As I understood it, the way the USP functions, it can only respond to a request from industry,” explained Dr. Sanders, “The USP needs a company to come to them and request verification.”

At this point, there is no incentive for a company to make such a request because they claim that consumers are not questioning what is written on the product label. “Things are not going to change until there is a demand from the marketplace,” she said. “What is needed is one or two companies to come forward and have their claims verified independently,” Dr. Sanders continued, suggesting that properly tested products might have a market advantage that would force all competitors to have their products tested.

Similar sentiments were expressed by researcher Gregor Reid, PhD, at the Canadian Research and Development Centre for Probiotics, University of Western Ontario . In a telephone interview he said, “The problem is the majority of the so-called probiotics products out there are unproven, though not harmful.” Even if companies meet the viable count standards that would allow them to be called yogurt, explained Dr. Reid, this would not be enough to call them probiotics. Rather, the specific live bacteria identified on the label must have been proven in a clinical trial to prevent or treat an illness or confer a defined health benefit, he explained. The live bacteria must also be at the same amounts used in the clinical trial.

Dr. Reid, a Professor of Microbiology and Immunology, and Surgery, is also concerned about the lack of incentive for companies to put out a high-quality product. Two companies in Canada pulled their products off the shelf, despite the fact that they had a proven benefit in clinical trials, Dr. Reid said, explaining that one company found it was cheaper to sell an inferior version of its own product. Can consumers trust any probiotic products that have been proven in studies to confer a health benefit? Dr. Reid answered in the affirmative, but the list* is short and none made it into the Consumer Reports article:

  • Culturelle with Lactobacillus GG , a supplement made by ConAgra, prevents and treats diarrhea;
  • VSL#3, made by VSL Pharmaceuticals, Inc. Fort Lauderdale , FL, keeps ulcerative colitis in remission;
  • Activia with Bifidus Regularis TM yogurt, made by Dannon, maintains regularity;
  • Florastor capsules and powder, made by Biocodex , France , maintains intestinal health and normal bowel function in infants, children, and adults;
  • Lactobacillus reuteri (capsules), made by Nature’s Way, treats diarrhea;
  • and Align containing Bifantis TM , made by Procter & Gamble, Cincinnati, Ohio, relieves abdominal pain/discomfort, bloating/distention, and bowel problems.

Dr. Reid has published numerous studies and commentaries about probiotics and owns patents on Lactobacillus strains GR-1 and RC-14. (Both strains are marketed in Europe to maintain the “balance of vaginal flora” under the brand name, Ombe, but this product is not yet available in the U.S. ) He has been working to improve quality and standards for products that claim to be probiotics. For example, the live bacteria in the products should be present for the length of shelf life. And the products should specify the exact strain of live bacteria, for example Lactobacillus acidophilus NCFM TM , as opposed to simply listing Lactobacillus acidophilus on the label.

It should be noted, however, that uncertainties about quality apply to all dietary supplements, including vitamins and herbal products, because this is an unregulated industry. One cannot be sure that any of these products contain what it says on the label because products classified as dietary supplements are not required by the FDA to undergo testing for safety or effectiveness.

When Dr. Sanders was asked what products currently on the market could be expected to be truly probiotics, she prefaced her answer by saying, “I’m not in any better position to answer that question than consumers because there is no third party verification.” Dr. Sanders did, however, single out three products-Culturelle supplements , DanActive TM yogurt drink, and Stonyfield Farm organic yogurt. (The last two products got the highest ratings by Consumer Reports.)

By way of disclosure, Dr. Sanders said that she serves on the scientific advisory board for Dannon, the company that makes DanActive TM , which claims to “naturally strengthen your body’s defense system.” Dr. Sanders points out that DanActive TM appropriately identifies the presence of 10 billion Lactobacillus casei cultures per serving on its label. [Editorial note: two other strains are listed on the label of DanActive TM without mention of the amount of cultures.] Dr. Sanders is not only a consultant for the probiotics industry but also an adjunct research professor at California Polytechnic State University .

While Stonyfield yogurt is one of Dr. Sanders’s three picks for products that appear to be probiotics, she expressed dissatisfaction about companies that do not inform consumers about the amount of live bacteria. “Stonyfield lists the six live active cultures on the label, but the company will not reveal the level of each strain or whether they are still active at the end of shelf life,” she said. “The company says it is proprietary information.”

Probiotics Research at a Turning Point

While there are plenty of reasons to be skeptical about the majority of probiotics on the market, there are also reasons to be optimistic. Dr. Reid spoke of a mindset in the mainstream research establishment that is dismissive of probiotics research and of his frustration about where the lion’s share of the research funding goes. “It’s drugs, drugs, drugs.” But he also reports a sea change in the last few years, much of it related to concerns about antibiotics. “Until a few years ago, we [probiotics researchers] were laughed at by our peers-both scientists and physicians. Now with the problem of resistant antibiotics, there is patient demand, and physicians are starting to pay attention.

” There are a number of reasons why probiotic research has become a hot topic. Despite over 50 years of antibiotics, infectious diseases remain a major cause of death, with gastroenteritis killing a child every 15 seconds. Antibiotics kill normal bacteria as well as good bacteria; hospital-borne infections are not declining; multiple-drug-resistant bacteria continue to emerge as the antibiotic pipeline dries up; pathogenic microbes are being linked with the induction or worsening of many chronic diseases.

“Add to this the pending threat of a deadly flu pandemic. All this has led to consideration of probiotics as one of the possible anti-disease countermeasures. Worried consumers, governments, scientists and industries are looking for new approaches to health restoration and retention. Probiotics have already been shown to alleviate some disease processes, so we need to explore their true potential, as well as understand their limitations.”

* All products can be purchased in the U.S. without a prescription. VSL #3 is available only at or by calling 1(866-GET-VSL3).

Maryann Napoli, Center for Medical Consumers ©
January 2006

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