OTCs Today
Daniel L. Krinsky, RPh, MS
In today’s climate of self-management for optimal health and wellness, use of prebiotics and probiotics has become increasingly popular. Pre- and probiotics can support gut health and provide other beneficial health effects. Multiple studies have confirmed their beneficial effects on various aspects of GI tract function as well as for other disorders, although more research is required.
Prebiotics
Prebiotics are substrates selectively used by host microorganisms—the enteric microflora—to promote gut health. They support the enteric microbiota and are typically substances fermented in the colon.
Some types of fiber act as prebiotics. The undigested fiber enters the colon and is fermented by bacteria, primarily bifidobacteria and lactobacilli. Fermentation products produce an environment favorable to growth of these beneficial bacteria. Inulin-type fructans, including fructooligosaccharides (FOS), are the most common prebiotics. They are found in small amounts in asparagus, bananas, chicory, Jerusalem artichoke, leek, onion, soy, and wheat. Other sources of prebiotics are conjugated linoleic acid, polyunsaturated fatty acid, and human milk oligosaccharides.
Both inulin-type fructans and FOS significantly increase bifidobacteria in the human gut. Doses vary greatly in studies. Beneficial effects of prebiotics supported by some human data include stool bulking and decreased constipation, better absorption of calcium and magnesium, reduced triglycerides, and stimulation of bifidobacteria growth. Use for treatment or prevention of diarrhea have yielded conflicting results. Other possible benefits of prebiotics are improved vaccine response, fewer GI infections, stimulation of intestinal hormonal peptides, clinical improvement in inflammatory bowel disease, and reduced tumor growth.
Probiotics
Probiotics are nonharmful living microorganisms that have beneficial health effects when ingested in sufficient amounts. Lactic acid–producing bacteria, especially Lactobacillus, Bifidobacterium, and Streptococcus, are most often used in commercially available foods and in studies. Beyond early infancy, these microorganisms do not permanently colonize the GI tract and must be ingested regularly to maintain their presence.
When present in adequate or optimal numbers, probiotics reduce colonization by pathogenic organisms and enhance mucosal defenses in the GI tract. Multiple species and strains of common probiotic bacteria exist, and effects cannot be extrapolated across species or even across different strains. The optimal dose for a given probiotic is not known; however, studies showing efficacy typically use a minimum of 107 to 1010 colony-forming units (CFU) per dose or 108 to 1010 CFU daily.
Dietary sources and daily requirements
Many traditional foods are fermented by bacteria and contain high concentrations of lactobacilli. Corn, cassava, millet, leafy vegetables (e.g., cabbage), and beans commonly serve as basic foodstuffs for fermentation. A few fermented foods are occasionally eaten in the United States, such as brined olives, kimchi, sauerkraut, and tempeh; however, the major food source of probiotic bacteria is “cultured” dairy foods. Many major brands of yogurt contain probiotic bacteria, although viable cultures are not required for yogurt in the United States, and labels do not list the number of viable probiotic organisms.
New products with added probiotic organisms appear regularly, sometimes with limited or no data on the organisms contained or on the efficacy of the combinations used. Research covers a wide range of disease states and participants of all ages.
Clinical data are preliminary, but moderate-quality evidence supports the use of probiotics for certain GI disease states, allergies, dermatologic conditions, metabolic and respiratory syndromes, and modification of cardiovascular risk factors.
Study results may be influenced by the dose, frequency of dosing, and/or organisms in any specific probiotic product. Many probiotic preparations with one or multiple species and wide dosing ranges are available.
Patient guidance
Health care providers and consumers should be thoughtful when selecting probiotic formulations and should base this decision on clinical trial data and the strains used in these trials. Counsel patients to avoid probiotics if they are immunocompromised or have risk factors for systemic infections or other complications.