Dietary supplementation of vitamin D prevents the development of western diet-induced metabolic, hepatic and cardiovascular abnormalities in rats.

Background: The western diet high in fat and fructose may cause metabolic disorders and cardiovascular diseases.

Objective: To evaluate whether long-term daily vitamin D supplementation prevents hepatic steatosis and cardiovascular abnormalities and restores insulin sensitivity caused by fat diet in rats without vitamin D deficiency.

Methods: Three groups of rats were fed for 6 months with standard diet (SD), western diet (WD) or WD containing 23 IU/day/rat vitamin D, respectively. Tail-cuff systolic blood pressure (SBP)measurements in conscious rats and transthoracic echocardiography were performed in basal condition, and after 3 and 6 months of diet. Hepatic steatosis and myocardial fibrosis were assessed in liver and cardiac tissues using standard methods. Serum insulin and 25(OH)D3 concentrations were determined using rat-specific ELISA kits. Insulin resistance was determined according to the homeostasis model assessment of insulin resistance (HOMA-IR) method.

Results: Sixty-one per cent of hepatocytes in WD rats had steatotic vacuoles compared with just 27% in rats on a WD plus vitamin D ( < 0.05).HOMA-IR was reduced in rats with vitamin D supplementation compared with WD alone (19.4 ± 5.2 vs 41.9 ± 8.9,  < 0.05). Rat blood pressure and left ventricular mass were both reduced by vitamin D supplementation.

Conclusion: In animal models of liver and cardiovascular metabolic damage, the supplementation of vitamin D shows liver and cardio-protective effects.