Vitamin D and cardiovascular risk among adults with obesity: a systematic review and meta-analysis

Background Obesity is a risk factor for both vitamin D deficiency and cardiovascular disease. A link between vitamin D status optimisation and improved cardiometabolic profile among adults with obesity could inform public health initiatives. Methods PubMed, Embase and Web of Science were searched for interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors (anthropometric measures, lipid profile, blood pressure, glucose tolerance) among nondiabetic adults with obesity. Results Seventeen publications reporting results from 11 different studies were included. Number of participants ranged from 34 to 1179 subjects. Duration was between 6 weeks and 4 years. Vitamin D was administered as a supplement in ten studies (1000 IU daily to 120 000 IU fortnightly). In one study, participants were advised to increase sunlight exposure and dietary vitamin D intake. The random and fixed-effects meta-analysis showed that vitamin D significantly increased systolic blood pressure and LDL-C levels. The fixed-effects model also indicated a significant decrease in triglyceride levels, which was not evident using the random-effects model. Caution should be given to these results given the small number of studies used and the high heterogeneity between studies for the two latter outcomes. Additionally, a subset of eligible studies with compatible data presentation was included in the meta-analysis. Conclusion This systematic review highlights a paucity of interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors among otherwise healthy adults with obesity. Large-scale studies at pharmacologically relevant doses and with sufficient duration are warranted.