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

 The prevalence of childhood obesity and its complications has increased in the world. Obesity, along with a lack of antioxidants, as a result of an unhealthy diet, might modify the balance in favor of oxidative stress.

 The current study aims to assess current literature on the relationship between obesity and antioxidant status through systematic review and meta-analysis.
Data Sources: This systematic review and meta-analysis study was performed on English language full-text articles published until September 2020 without any time limit. Electronic search was conducted in international databases of Google Scholar, Pub Med, Web of Science, Scopus, Medline, and Cochrane.

Study Selection:

First1255 papers were found in the primary search, after removing duplicates and quality assessment 46 of them were used in the systemic review and 19 articles were entered into the meta-analysis.

Data Extraction:

Two independent researchers searched the following keywords: 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. Articles research on animal, interventional studies, case studies, case reports, irrelevant studies were excluded. The research team determined the quality of studies using the checklist on strengthening the Reporting of Observational Studies in Epidemiology (STROBE). Heterogeneity of studies was evaluated using index (I2) and probability of diffusion bias by funnel plot and Begg’s and Egger’s tests.

 Beta-carotene levels children was significantly lower in obese children than non-obese (Mean difference: 0.13, 95% CI: 0.09-0.16, P-value<0.001), with significant heterogeneity (P-value< 0.001, I2 = 85%). There was a significant difference between obese and non-obese children in both alpha-tocopherol (pooled mean difference respectively: 0.36, 95% CI: 0.04-0.96, P-value<0.001) with non-significant heterogeneity (P-value>0.05, I2 = 0.0%) and alpha-tocopherol per lipoid (pooled mean difference: 0.42, 95% CI: 0.28-0.55, P-value<0.001), with significant heterogeneity (P-value=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-value>0.05), with significant heterogeneity (P-value< 0.001, I2 = 84.5%). There was significant association between Zinc, Magnesium, Copper, and selenium level and obesity (P-value>0.05), with significant heterogeneity (P-value< 0.001).

 This review revealed 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.