High to moderate certainty in the body of evidence suggests that LGG supplementation ( regardless of the timing of administration ) did not reduce the risk of eczema .
There was also no consistent effect on other allergic outcomes .
This meta- analysis shows that LGG was ineffective in reducing eczema .
Current guidelines recommend the use of probiotics to reduce the risk of  eczema .
It remains unclear which strain(s ) to use .
We systematic ally evaluated data on the efficacy of Lactobacillus rhamnosus GG ( LGG ) supplementation prenatally and /or postnatally for the primary prevention of eczema .
Harms Reporting in Randomized Controlled Trials of Interventions Aimed at Modifying Microbiota
IN RESPONSE : We agree with Dr. Baldassarre that the regulatory model for approval of probiotics , prebiotics , and synbiotics could alter the evaluation of adverse events in r and omized controlled trials , which may cause study publications to omit some safety data . This regulatory model has remained ambiguous and complex and varies by region ( 1 , 2 ) . Probiotics that have a long historical use or are used as additives or processing aids have been subject to few or no regulations . In contrast , those intended for new therapeutic purpose s must follow a strict process for approval ( 3 ) . We recognize that the safety and efficacy findings associated with a specific probiotic formulation should not be generalized to a new formulation . Knowing the precise identity of a probiotic that was assessed in a r and omized controlled trial is fundamental to determine its exact safety profile . The identification methods typically used ( such as pulsed-field gel electrophoresis and r and omly amplified polymorphic DNA analysis ) allow for differentiation of individual strains but are otherwise inadequate for species recognition ( 2 ) . Inconsistencies in the bacterial identification for probiotics may lead to a biased safety profile and erroneous decision making and have major consequences for patients . It is crucial that toxicology of these products take into account the dose , formulation , bacterial species , and target population . That all stakeholdersincluding laboratories , government regulatory authorities , and scientistsbe prepared to address this important topic is critical . Nevertheless , problems with the regulatory model can not fully explain why 28 % of trials did not report any information on harms and 70 % inadequately reported harms-related data . Poor reporting of harms may be due to distorted reporting of adverse events in the trials , silencing the evidence on harms , or lack of knowledge on how to report adverse events in publications ( 4 ) . Inadequate reporting of adverse events in published articles of r and omized controlled trials remains a major problem in several medical areas . We need to promote more active implementation and endorsement of recommendations for st and ardizing the evaluation of these interventions and reporting harms-related data . The points raised by Dr. Baldassarre and the findings of our study highlight that a collective , international effort is urgently needed to improve the evaluation of these products
High to moderate certainty in the body of evidence suggests that LGG supplementation ( regardless of the timing of administration ) did not reduce the risk of eczema .
There was also no consistent effect on other allergic outcomes .
This meta- analysis shows that LGG was ineffective in reducing eczema .
Current guidelines recommend the use of probiotics to reduce the risk of  eczema .
It remains unclear which strain(s ) to use .
We systematic ally evaluated data on the efficacy of Lactobacillus rhamnosus GG ( LGG ) supplementation prenatally and /or postnatally for the primary prevention of eczema .