Overview
Overweight and obesity in children and adolescents are pressing global health concerns linked to adverse cardiometabolic outcomes. Questions remain about whether vitamin D supplementation can modulate cardiometabolic risk factors such as insulin resistance, lipid profiles, blood pressure, and inflammatory markers in this population. This article summarizes a grade-assessed systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the impact of vitamin D supplementation on cardiometabolic health among youths with excess weight.
The Rationale for Vitamin D in Youth Cardiometabolic Health
Vitamin D plays a role beyond bone metabolism. It participates in immune function, inflammation regulation, and metabolic pathways related to insulin sensitivity and lipid handling. In children and adolescents who are overweight or obese, vitamin D deficiency is common, and low vitamin D status has been associated with higher cardiometabolic risk. Clinicians and researchers have sought to determine whether supplementation could improve cardiometabolic profiles in this vulnerable group.
Methods at a Glance
The review integrated data from randomized controlled trials that explored vitamin D supplementation versus placebo or standard care in youths with overweight or obesity. Key outcomes included measures of insulin resistance (e.g., HOMA-IR), fasting glucose and insulin, lipid parameters (LDL-C, HDL-C, triglycerides), blood pressure, inflammatory markers (e.g., C-reactive protein), and adipokines. The authors applied a rigorous grading framework to assess certainty of evidence and synthesized results through meta-analysis where data allowed.
Main Findings
Across identified studies, results were nuanced. Some trials reported modest improvements in insulin resistance markers or fasting insulin with vitamin D supplementation, particularly among participants who started with lower baseline vitamin D levels. However, the aggregated evidence often showed small, non-consistent effects on lipid profiles, blood pressure, or systemic inflammation. The certainty of evidence ranged from low to moderate for several outcomes, reflecting variability in study design, supplementation dosage and duration, baseline vitamin D status, adherence, and coexisting lifestyle factors such as diet and physical activity.
Insulin Resistance and Glucose Metabolism
A subset of trials suggested potential improvements in insulin sensitivity and fasting insulin after vitamin D supplementation, but results were not uniform across studies. The overall conclusion indicates potential benefit in specific subgroups (eg, those with deficiency), while indicating the need for caution in generalizing findings to all overweight or obese youths.
Lipid Profile and Blood Lipids
Findings for lipid outcomes were inconsistent. Some studies noted minor changes in triglycerides or LDL-C, but no consistent, clinically meaningful lipid improvement emerged after pooling data. Heterogeneity in baseline lipids and concomitant lifestyle interventions likely contributed to divergent results.
Blood Pressure and Inflammatory Markers
Evidence for blood pressure effects and inflammatory markers was limited and did not demonstrate robust benefits of vitamin D supplementation in the overall population. Any observed trends often aligned with study-specific factors such as age range, pubertal stage, and duration of supplementation.
Strengths and Limitations
Strengths include a comprehensive, predefined protocol and rigorous risk-of-bias assessment using a grading framework that informs certainty of evidence. Limitations involve small sample sizes in several trials, variability in vitamin D dosing regimens, differences in the duration of supplementation, and heterogeneity in participant characteristics and co-interventions. These factors contribute to the overall modest certainty for most cardiometabolic outcomes.
Clinical and Research Implications
Vitamin D supplementation may offer targeted benefits for overweight and obese children and adolescents who are vitamin D deficient, particularly regarding insulin resistance markers. However, routine supplementation solely for improving broad cardiometabolic risk, in the absence of deficiency, is not currently supported by high-certainty evidence. Clinicians should prioritize a holistic approach—balanced nutrition, physical activity, weight management, and vitamin D repletion when deficient—while awaiting more robust, large-scale randomized trials with standardized dosing and longer follow-up.
Practical Takeaways
- Assess vitamin D status in youths with overweight or obesity, especially if metabolic risk is a concern.
- Consider vitamin D repletion in deficient individuals as part of a broader cardiometabolic strategy.
- Avoid relying on vitamin D supplementation alone to achieve cardiometabolic health; lifestyle modification remains central.
Conclusion
Current grade-assessed evidence suggests that vitamin D supplementation may offer limited cardiometabolic benefits for overweight and obese children and adolescents, with possible gains primarily in those with deficiency. The overall certainty remains modest, underscoring the need for ongoing high-quality RCTs to clarify which subgroups might benefit most and under what dosing and duration. In the meantime, a comprehensive approach to weight management and metabolic health continues to be essential.
