The quality of evidence on nutrition intervention published in Chinese journals: an assessment of meta-analyses on vitamin interventions

Background and Objectives: The quality of meta-analyses (MAs) on nutrition intervention in mainland China remains uninvestigated. To assess the quality of the evidence regarding nutrition intervention in mainland China, we used vitamin intervention as an example to assess the overall methodological and reporting qualities of MAs on nutrition interventions published in Chinese journals. Methods and Study Design: A cross-sectional study on MAs of vitamin interventions was performed. Four Chinese databases were searched from inception through September 2016 for all MAs of vitamin intervention. A Measurement Tool to Assess Systematic Reviews (AMSTAR) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statements were used to assess methodological and reporting qualities, respectively. Results: A total of 43 MAs of vitamin interventions were included, but none of the studies had been updated. These reviews mainly focused on the effects of interventions involving vitamin D, B vitamins and vitamin E, and the most studied condition was "Endocrine, Nutritional and Metabolic diseases," such as diabetes, obesity, and nutritional rickets. The median AMSTAR score was 6 (0-7), and median PRISMA score was 18 (3-24). No study provided an 'a priori' design, a list of excluded studies, or a statement on conflict of interest, and less than 50.0% of included MAs stated the publication status and performed an adequate structure summary. Conclusions: The quality of the included MAs was disappointing regarding some items, and some lower quality reviews should be updated. Future MAs should improve on reporting conflicts of interest, harm, and publication bias.