The prevalence of atopic diseases in Western countries is showing a dramatic increase. Recent epidemiological studies and experimental research suggest that gut microbiota may have a role in the development of atopic disorders. As such, prebiotic and probiotic supplements have been tested for primary prevention and/or treatment of AD. Until now, the results of isolated trials and meta-analyses using probiotics and prebiotics to prevent or treat AD have been inconsistent. Synbiotics are products that contain both probiotics and prebiotics and have also been used for either prevention or treatment of AD, but results are inconsistent.
Dr García-Romero and her team conducted a systematic review and meta-analysis to investigate the efficacy of synbiotics for primary prevention and treatment of AD. The authors included all published RCTs until October 2015. The primary outcomes were the Severity Scoring Atopic Dermatitis (SCORAD) index (treatment studies) and the incidence of AD (prevention studies). A total of 276 studies were initially identified. For the final meta-analysis, only 6 treatment studies and 2 prevention studies met the quality criteria for inclusion.
The most relevant results are summarised below:
Overall, there was a significant decrease in the SCORAD index in the synbiotics group compared to the control group after 8 weeks of treatment. Treatment duration over 8 weeks did not confer any additional benefit.
Mixed-strain bacterial species (3 studies) had a significant effect on improving the SCORAD index, compared to single-strain synbiotics.
Synbiotics significantly improved the SCORAD index for children aged 1 year or over with AD, without having a significant effect on infants under 1 year.
There is no evidence yet to suggest the use of synbiotics for the prevention of AD.
In conclusion, the up-to-date weak evidence suggests that synbiotics may be useful in the treatment of AD, especially when using a mixed-strain probiotic component and among children aged 1 year or over.
Andreu Prados Andreu Prados holds a Bachelor of Science Degree in Pharmacy & Human Nutrition and Dietetics. Science writer specialised in gut microbiota and probiotics, working also as lecturer and consultant in nutrition and healthcare. Follow Andreu on Twitter @andreuprados