AUTHOR=Zhang Yi , Ding Jun , Guo Hongbin , Liu Ze , Liu Qi , Li Yusheng , Zhang Dianzhong , Liang Jieyu 

TITLE=Associations of Dietary and Circulating Vitamin E Level With Metabolic Syndrome. A Meta-Analysis of Observational Studies

JOURNAL=Frontiers in Nutrition

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.783990

DOI=10.3389/fnut.2021.783990

ISSN=2296-861X

ABSTRACT=<p><bold>Objective:</bold> The associations of dietary and circulating vitamin E level with metabolic syndrome (MetS) remains conflicting. This meta-analysis of observational study was therefore employed to investigate the issue above.</p><p><bold>Methods:</bold> The PubMed, Web of Science and Embase database were searched up to April 2021. The observational studies on the associations of dietary and circulating vitamin E level with MetS were specified. The pooled relative risk (RR) of MetS for the highest vs. lowest dietary and circulating vitamin E level, and the standard mean difference (SMD) of dietary and circulating vitamin E level for MetS vs. control subjects, were calculated.</p><p><bold>Results:</bold> A total of 25 observational studies with 51,276 participants, were included in this meta-analysis. The overall multi-variable adjusted RR demonstrated that the dietary vitamin E level was inversely associated with MetS (RR = 0.92, 95%CI: 0.85–1.00; <italic>P</italic> = 0.044). In addition, the dietary vitamin E level in MetS was also lower than that in control subjects according to the overall combined SMD (SMD = −0.08, 95%CI: −0.14 to −0.02; <italic>P</italic> = 0.024). On the other hand, the overall multi-variable adjusted RR showed no significant relationship between the circulating vitamin E level and MetS (RR = 1.46, 95%CI: 0.85–2.48; <italic>P</italic> = 0.17). However, the circulating vitamin E level in MetS was lower than that in control subjects according to the overall combined SMD (SMD = −0.58, 95%CI: −1.04 to −0.13; <italic>P</italic> = 0.013).</p><p><bold>Conclusions:</bold> The results of this meta-analysis suggest that the dietary vitamin E level is inversely associated with MetS. On the other hand, current evidence is still insufficient to conclude a relationship between the circulating vitamin E level and MetS. More well-designed prospective cohort studies are needed to address the issues further.</p>