Probiotics for preventive health.

Gut flora and probiotics have potential to affect health and disease far beyond the gut. There is increasing evidence that probiotics have beneficial effects in preventing a wide range of conditions and improving health. Randomized, double-blind studies have provided evidence of the effectiveness of probiotics for preventing various diarrheal illnesses as well as allergic disorders. Evidence for their efficacy for use in the prevention and treatment of bacterial vaginosis and urinary tract infections is also mounting. In addition, probiotics may be useful for preventing respiratory infections, dental caries, necrotizing enterocolitis, and certain aspects of inflammatory bowel disease. Data also suggest that probiotics may promote good health in day care and work settings, and may enhance growth in healthy as well as ill and malnourished children. Results from meta-analyses and systematic reviews that combine results of studies from different types of probiotics to examine the effects in any disease state should be interpreted with caution. Specific strains are effective in specific disease states. No 2 probiotics are exactly alike; we should not expect reproducible results from studies that employ different species or strains, variable formulations, and diverse dosing schedules.