Childhood Obesity and Its Correlation With Vitamin D: A Systematic Review.

Several studies have identified a correlation between vitamin D deficiency and childhood obesity. The aim of this study is to perform a systematic review of data collected to determine how significant the effect of vitamin D deficiency is on childhood obesity and to determine the extent to which vitamin D deficiency has a predictive association with health status in the pediatric population, where obesity is a concern. This review will add value to the current body of knowledge and provide valuable clinical guidance in avoiding the negative effects of vitamin D deficiency on childhood obesity. A systematic literature review was conducted through a variety of resources, including MEDLINE, Google Scholar, PubMed, and JSTOR. The following search terms were used to identify relevant studies discussing the correlation between childhood obesity and vitamin D deficiency: "vitamin D", "childhood obesity", "pediatrics", and "vitamin D deficiency". Citations were screened and assessed for quality via Rayyan (Rayyan Systems Inc., Cambridge, MA), a web application. If an article met the exclusion criteria, it was excluded from the analysis. Of the selected studies, data on the association between vitamin D deficiency and childhood obesity were presented and discussed. The majority of the chosen investigative studies found a statistically significant association between vitamin D deficiency and childhood obesity. The studies reported a significant inverse correlation between body mass index (BMI) and vitamin D levels, and the pooled correlation coefficient (r) was approximately -0.299 (p<0.01), indicating a moderate inverse relationship. Additionally, the majority of the studies stated that the chances of having vitamin D deficiency increase with a pooled odds ratio of 2.6 (95% confidence interval (CI): 1.4-4.76). These findings also suggested potential bidirectional relationships. Obesity may reduce vitamin D levels (due to sequestration of vitamin D in fat tissue), and low vitamin D levels might also influence body weight and fat accumulation through effects on metabolism and insulin sensitivity. Clarifying the direction and nature of this relationship is important for treatment strategies, screening obese children for vitamin D deficiency, or vice versa, improving patient care. Understanding this relationship could help in developing targeted nutritional or physical activity guidelines, supplementation programs, or obesity prevention campaigns. Along with obesity, vitamin D further demonstrates relationships in more specific metabolic disorders such as impaired fasting glucose, lipids, and parathyroid hormone (PTH), although with some conflicting findings. The mechanism behind these associations implicating vitamin D as a causal factor remains overall unclear. However, evidence certainly supports a close relationship in these metabolic concerns, to support the potential coexistence of these concerns and to consider broad testing and treatment accordingly.