Evidence Updates including professional commentaries: Safety of Probiotics to Reduce Risk and Prevent or Treat Disease.

"....Existing studies primarily examined Lactobacillus alone or in combination with other genera, often Bifidobacterium.

Few studies directly compared the safety among different intervention or participant characteristics. Indirect comparisons indicated that effects of delivery vehicles (e.g., yogurt, dairy) should be investigated further.

Case studies suggested that participants with compromised health are most likely to experience adverse events associated with probiotics. However, RCTs in medium-risk and critically ill participants did not report a statistically significantly increased risk of adverse events compared to control group participants.

Conclusions. There is a lack of assessment and systematic reporting of adverse events in probiotic intervention studies, and interventions are poorly documented. The available evidence in RCTs does not indicate an increased risk; however, rare adverse events are difficult to assess, and despite the substantial number of publications, the current literature is not well equipped to answer questions on the safety of probiotic interventions with confidence."