Georgetown University Medical Center, Washington, DC (Dr. Merenstein); International Scientific Association for Probiotics and Prebiotics, Centennial, CO (Dr. Sanders); University of California Davis School of Medicine and Center for Healthcare Policy and Research, Sacramento (Dr. Tancredi) djm23@georgetown.edu
Dr. Merenstein reported no potential conflict of interest relevant to this article.
Dr. Sanders consults with companies engaged in probiotic business, but has no financial stake in any company. She serves on scientific advisory boards for Danone, Yakult Honsha Co., Ltd, Danone North America, and Winclove.
Dr. Tancredi has received statistics educational consulting fees from Pfizer Consumer Health.
The granular data we provide can help shape recommendations of a product for a specific indication. Numerous probiotics have been tested on suboptimal gastrointestinal health, including managing functional bowel symptoms ranging from occasional gas, bloating, or constipation through diagnosed irritable bowel syndrome (IBS). Supplements such as Bifidobacterium infantis subsp. longum 35624 (the probiotic in Align), Lactobacillus plantarum 299V (the probiotic in NatureMade Digestive Probiotic Daily Balance), and foods such as Activia yogurt, Yakult cultured milk, or Good Belly juice can be recommended for digestive symptoms.
Base your probiotic dosages on levels shown to be effective in clinical trials, which can be as low as 100 million CFU/d.
For patients experiencing gut symptoms unrelated to diagnosed disease, it may be reasonable for them to try a well-documented strain for 3 to 4 weeks. Currently it is difficult to predict success a priori; this may change as we learn more about how an individual’s microbiome, diet, and genetics affect response to specific probiotics. TABLE 268-71presents sample recommendations from international expert panels for select contexts.
The popular press today commonly recommends consuming more fermented foods. Although we agree in general with this recommendation, physicians should be clear that fermented foods may be a source of live cultures, but not all fermented foods retain live microbes. Further, many fermented foods lack evidence documenting health effects, and therefore are not a source of probiotics. If the patient’s goal is to support regular diet with live microbes, any number of probiotic products or fermented foods that retain viable cultures may suffice. However, when patients request probiotics for specific needs, recommendations should be based on available evidence for specific studied products. (See also, “Questions patients frequently ask about probiotics.”)
SIDEBAR 9 questions patients frequently ask about probiotics
Q. Is a higher dose and greater number of strains better?
A. Not necessarily. The best approach is to recommend products that have been tested in human studies with positive outcomes. Sometimes these products are single strain and have doses lower than other commercial products. If your patient’s goal is to simply add live, potentially beneficial microbes to a diet, and he or she is not presenting with any specific health complaints, then fermented foods or any probiotic supplement should be sufficient.
Q. Is yogurt a good choice for managing antibiotic-associated diarrhea (AAD)?
A. In patients at high risk, recommend a probiotic from TABLE 1. 3-32 Simply recommending “yogurt” is not a strong recommendation, since few yogurts contain specific probiotics that are known to help with AAD. Yogurt usually contains live cultures, but the only cultures required in yogurt (Lactobacillus bulgaricus and Streptococcus thermophilus) do not survive intestinal transit and, with the exception of improving lactose digestion, are not likely to promote digestive health. Yogurts stipulating the strain and dose of added microbes are more likely to be supported by evidence.
Q. Does the sugar in probiotic yogurts negate the benefits of probiotic yogurt?
A. Most studies testing the health benefits of yogurt have been conducted on sweetened yogurts. Therefore, the sugar present in these products does not negate the probiotic effects. However, sweetened yogurts should be consumed as part of a balanced diet.
Q. Are probiotics beneficial for healthy people?
A. Studies have shown that probiotics can modestly decrease the incidence and duration of some common infectious symptoms such as those occurring in the gastrointestinal and upper respiratory tracts. These studies have been conducted on healthy subjects. But like multivitamins, improving health in healthy people is difficult to demonstrate.
Q. Are probiotic products unregulated?
A. Most probiotic products in the United States are marketed as foods or dietary supplements. These products are regulated by the US Food and Drug Administration (FDA), but not in the same way drugs are regulated. The FDA does not conduct premarket review of data on safety or health benefits. However, the FDA requires that these products are manufactured under current Good Manufacturing Procedures. Further, products are required to be labeled in a truthful (and not misleading) fashion. Enforcement of these standards requires action by the FDA, and limited resources within the agency result in products on the market that may not comply with standards.
Q. Are refrigerated products better than nonrefrigerated?
A. The stability of the live microbes in a probiotic product depends on product formulation and conditions of storage. Some products may require refrigeration, but others do not. Responsible product manufacturers make certain that their probiotic is able to meet the label claim through the end of shelf life if stored as recommended.
Q. Is it better to take probiotics as supplements or foods?
A. It is important to take the product tested for the specific effect, whether it is in food or supplement format. If products with equivalent efficacy are available in different formats, then have patients take the product that best fits with his or her diet and lifestyle.
Q. What is the difference between probiotics and prebiotics?
A. Probiotics are live microorganisms beneficial to one’s health. Prebiotics are not live microbes, but are substances that are used by beneficial, resident microorganisms. Simply put, prebiotics are food for the beneficial bacteria in your gut. Most prebiotics are a type of fiber.
Q. The body already has so many bacteria, how can we expect the comparatively small number of live microbes in a probiotic product to have any benefits?
A. Our bodies are home to trillions of microbes. But remember that we are not uniformly colonized, even throughout the digestive tract. Orally consumed probiotics travel through some sparsely colonized regions of the upper digestive tract, and may become dominant in those segments. But even as minor components of the lower digestive tract, probiotics can impact the gut environment and clinical outcomes.
