One of the primary complaints about taking antibiotics (and the main reason for poor compliance) is the gastrointestinal effects that they cause; about 30% of the population experiences antibiotic associated diarrhea (AAD). Probiotics are the primary treatment recommended by many practitioners to alleviate or prevent AAD and to restore healthy GI flora.

In this meta-analysis, over 15,000 studies on probiotics were identified (thus contradicting concerns that supplements aren't well-researched). The pool was narrowed down to 63 studies that qualified for the meta-analysis based on set inclusion criteria. Lactobacillus and Saccharomyces were the most common probiotics used in studies, but others were included as single ingredients or in combination formulas. Participants included all ages, and all varieties of antibiotics were included in the research.

In this review, probiotic administration significantly reduced the risk of AAD, regardless of the type of antibiotic or probiotic used in the study. The authors of this meta-analysis concluded, "Our review found sufficient evidence to conclude that adjunct probiotic administration is associated with a reduced risk of AAD. This generalized conclusion likely obscures heterogeneity in effectiveness among the patients, the antibiotics, and the probiotic strains or blends. Future studies should assess these factors and explicitly assess the possibility of adverse events to better refine our understanding of the use of probiotics to prevent AAD."

Reference: JAMA. 2012;307(18):1959-1969