The Association Between Antioxidant Status and Excess Weight in Children: A Systematic Review and Meta-analysis

Background: The prevalence of childhood obesity with its complications has increased in the world. Obesity, along with antioxidants deficiency (due to an unhealthy diet), might change the balance in favor of oxidative stress. Objectives: The current study aims to assess the literature on the relationship between obesity and antioxidant status through a systematic review and meta-analysis Results: β-Carotene levels was significantly lower in obese children than non-obese ones (mean difference: 0.13, 95%CI: 0.09-0.16, P<0.001), with significant heterogeneity (P<0.001, I2=85%). There was a significant difference between obese and non-obese children in both α-tocopherol (pooled mean difference respectively: 0.36, 95% CI: 0.04-0.96, P<0.001 ) with non-significant heterogeneity (P>0.05, I2=0.0% ) and α-tocopherol per lipoid (pooled mean difference: 0.42, 95%CI: 0.28-0.55, P<0.001), with significant heterogeneity (P=0.048, I2=58.8%). There was no significant association between vitamin E level and obesity (pooled mean difference: 0.40, 95%CI: -0.05-0.85, P>0.05), with significant heterogeneity (P<0.001, I2=84.5%). There was significant association between zinc, magnesium, copper, and selenium level and obesity (P>0.05), with significant heterogeneity (P<0.001). Conclusions: This review revealed a significant inverse relationship between childhood obesity and serum antioxidant levels. More studies are necessary to find the underlying mechanisms and clinical impacts of this finding. Data Sources: This systematic review and meta-analysis were performed among English language articles published until September 2020 without any time limit. An electronic search was conducted in international databases of Google Scholar, PubMed, Web of Science, Scopus, Medline, and Cochrane. Study Selection: First, 1255 papers were found. After removing duplicates and quality assessment, 46 were used in the systemic review, and 19 articles were entered into the meta-analysis. Data Extraction: Two researchers independently searched the following keywords in the databases: “Vitamin C”, “Vitamin E”, “Vitamin A”, “Carotenoids”, “Antioxidants”, “Selenium”, “Magnesium”, “Copper”, “Zinc”, “Ascorbic acid”, “Tocopherol”, “Obesity”, “Overweight”, “Childhood”, “Pediatric”, and “Adolescence”. Articles that examined the association between obesity and antioxidant status were included in the study. The research on animals, interventional studies, case studies, case reports, and irrelevant studies were excluded. The research team determined the quality of studies using the STROBE (strengthening the reporting of observational studies in epidemiology) checklist. Heterogeneity of studies was evaluated using index (I2) and probability of diffusion bias by funnel plot and Begg’s and Egger’s tests.