Vitamin D and Chronic Disorders: A Review of Metabolic and Cardiovascular Diseases.

Vitamin D, long recognized for its essential role in calcium-phosphate balance and bone health, has increasingly been identified as a pleiotropic regulator of metabolic, cardiovascular, and renal function. Deficiency of vitamin D is widespread worldwide and has been linked to a higher risk of insulin resistance, type 2 diabetes, atherosclerosis, hypertension, and chronic kidney disease. Meta-analyses suggest that each 10 nmol/L (≈4 ng/mL) increase in serum 25-hydroxyvitamin D [25(OH)D] is associated with about a 4% lower risk of type 2 diabetes, whereas other analyses indicate an approximately 10% reduction in cardiovascular event risk per 10 ng/mL (≈25 nmol/L) increment in circulating 25(OH)D concentration. Clinical and epidemiological studies suggest that optimal 25(OH)D concentrations may protect against cardiometabolic and renal complications, though supplementation trials show heterogeneous outcomes depending on baseline vitamin D status, genetic background, and dosage. By synthesizing current knowledge, this work highlights vitamin D status as a potentially modifiable determinant of global disease burden and a target for preventive and therapeutic strategies.