Vitamin C and Metabolic Syndrome: A Meta-Analysis of Observational Studies

Abstract

Background: The association between vitamin C and metabolic syndrome (MetS) has been evaluated in several epidemiological studies with conflicting results. This meta-analysis was therefore employed to further investigate the above issue.Methods: The observational studies on the associations of dietary and circulating (serum and plasma) vitamin C levels with MetS were searched in the PubMed, Web of Science, and Embase database up to April 2021. The pooled relative risk (RR) of MetS for the highest vs. lowest dietary and circulating vitamin C levels and the standard mean difference (SMD) of dietary and circulating vitamin C levels for MetS vs. control subjects were calculated, respectively.Results: A total of 28 observational studies were identified in this meta-analysis. Specifically, 23 studies were related to the dietary vitamin C level. The overall multivariable-adjusted RR demonstrated that the dietary vitamin C level was inversely associated with MetS (RR = 0.93, 95% CI: 0.88–0.97; P = 0.003). Moreover, the overall combined SMD showed that the dietary vitamin C level in MetS was lower than that in control subjects (SMD = −0.04, 95% CI: −0.08 to −0.01; P = 0.024). With regard to the circulating vitamin C level, 11 studies were included. The overall multivariable-adjusted RR demonstrated that the circulating vitamin C level was inversely associated with MetS (RR = 0.60, 95% CI: 0.49–0.74; P < 0.001). In addition, the overall combined SMD showed that the circulating vitamin C level in MetS was lower than that in control subjects (SMD=-0.82, 95%CI: −1.24 to −0.40; P < 0.001).Conclusions: Current evidence suggests that both dietary and circulating vitamin C level is inversely associated with MetS. However, due to the limitation of the available evidence, more well-designed prospective studies are still needed.

Associations of Dietary Vitamin C and E Intake With Depression. A Meta-Analysis of Observational Studies

“…Vitamin C (ascorbic acid), an essential water-soluble micronutrient, is traditionally employed to prevent and treat scurvy ( 8 ). However, vitamin E (also known as tocopherol) is a fat-soluble vitamin to modulate enzymes involved in signal transduction, gene expression and immunomodulatory capabilities ( 9 , 10 ).…”

Associations of the Dietary Iron, Copper, and Selenium Level With Metabolic Syndrome: A Meta-Analysis of Observational Studies

“…However, the subjects suffering from MetS are progressively growing worldwide and the current global prevalence of MetS is between 11.6 and 62.5% (6). Although the etiology of MetS is not well understood yet, dietary factors are considered to be involved in MetS (7)(8)(9)(10)(11).…”

Dietary Patterns Derived from Reduced Rank Regression Are Associated with the 5-Year Occurrence of Metabolic Syndrome: Aichi Workers’ Cohort Study

“…A variety of nutrients have been linked to MetS or its components. Higher intakes of total fiber [ 8 , 20 , 21 ], vitamin C (VC) [ 22 ], magnesium (Mg) [ 23 , 24 ], potassium (K) [ 25 ], vitamin A or β-carotene [ 26 ], vitamin E (VE) [ 27 ] and omega-3 polyunsaturated (n3) fatty acids [ 28 , 29 , 30 ] and consuming relatively few carbohydrates [ 31 , 32 ] are inversely associated with MetS or its components in observational studies.…”