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Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
Probiotic supplements have gained popularity over the past few years and are often used to promote, improve, and maintain digestion. They also have been used to prevent or decrease the recurrence of vaginal yeast infections and treat conditions that may change normal intestinal flora (eg, antibiotic-associated, traveler's, and infectious diarrhea) and inflammatory and functional bowel conditions.1 A number of clinical studies have investigated the role of probiotics in treating various allergic conditions as well.
The World Health Organization and the Food and Agriculture Organization of the United Nations define probiotics as "live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host."1-3 Probiotics are normally present in the human gut or as components of foods, beverages, and supplements.1,3 According to the Handbook of Nonprescription Drugs, probiotics are linked to several actions. These include competition with pathogens for the binding sites on intestinal mucosa; the reduction of intestinal permeability; changes in the intestinal pH; and direct antimicrobial effect against some pathogens.1
Probiotics are often present in fermented products from milk (eg, yogurt, yogurt drinks, buttermilk), some juices and soy beverages, and plants (sauerkraut and miso). As dietary supplements, probiotics come in a variety of dosage forms, including capsules, tablets, and powders. In both probiotic foods and dietary supplements, the bacteria may be present already or added during preparation of the products.2
Research also has provided encouraging evidence about the uses of probiotics in the following areas2:
Research suggests that certain probiotics may have an impact on the mucosal barrier function of the intestinal tract, which affects allergens entering the body and the activity of inflammation-producing cells.4 One study concluded that probiotics may have a beneficial effect in allergic rhinitis by reducing symptom severity and medication use.5
Results from a study published in the August 2008 issue of Clinical & Experimental Allergy suggest that in the future, probiotics could be another treatment option for the estimated 35.9 million individuals in the United States who have seasonal allergic rhinitis (SAR).6 In this pilot study, researchers from the Institute of Food Researchers randomly assigned 10 study participants to drink a glass of regular milk or milk containing the probiotic Lactobacillus casei strain Shirota. L casei has been widely studied for its health benefits.6
The volunteers drank the milk each day and were evaluated for 5 months. At the start of the study, blood tests revealed similar levels of immunoglobulin (Ig) E between both groups of volunteers, but those who drank the probiotic drink had significantly lower levels of IgE specific for grass pollens and other allergy-related immune substances at peak season and afterward.5
Researchers agree that a larger scale study is needed to determine if the use of probiotic supplementation can decrease the symptoms associated with SAR.6 Researchers are hopeful that phase 2 of the study will provide more insight on whether probiotic supplementation provides symptom relief.6
A study by Wang et al reported that the use of probiotics improved the quality of life in individuals with allergic rhinitis.7 Other studies have reported that the use of the probiotic Lactobacillus rhamnosus strain GG can prevent atopic eczema in infants.1,8,9
For more information on current clinical trials studying probiotics, visit the National Institutes of Health's clinical trials Web site at www.clinicaltrials.gov/ct2/results?term=probiotics.
Probiotics may contain the species Lactobacillus, Bifidobacterium, and Saccharomyces. Within the Lactobacillus strain, Lactobacillus reuteri is the most prevalent strain found in the human body.1 Supplements currently on the market may contain L rhamnosus GG, reuteri, acidodphilus, bulgaricus, and fermentum.1 Strains of Bifidobacterium found in supplements include B longum, bifidum, breve, infanti, or lactis. Saccharomyces boulardii, which is yeast, is the only one of the Saccharomyces species that is used in dietary supplements.1
Probiotics, especially Lactobacillus, are often associated with immune-modulating and anti-inflammatory activities, including the decrease of tumor necrosis factor and stimulation of immunoglobulin and transforming growth factor B production.1
Prior to recommending the use of any probiotic supplements (Table), individuals— particularly those with concurrent medical conditions—should seek advice from their primary health care provider. Women who are pregnant or breast-feeding should always consult their doctors. Although the data are limited, no harmful results have been associated with the use of probiotics in late-term pregnancies or in women who are breast-feeding.1
Typically, probiotic supplements are well tolerated, but some patients may experience mild episodes of bloating and flatulence that tend to diminish over time.1 Incidence of diarrhea has been reported in the pediatric population.1 Patients who have any concerns about adverse effects should be encouraged to seek advice from their primary health care provider. Those individuals with compromised immune systems should be advised not to use probiotics because of the potential of systemic infections.1
Patients should be advised that concurrent administration of probiotic supplements and any antibiotics or antifungal agents is typically not recommended, and dosing intervals of these agents should be spaced by several hours.1 Patients should be reminded to only use products from reputable companies and to adhere to the manufacturer's dosage guidelines and directions for use.
For more information on the health benefits of probiotics, please visit the following Web sites: