REN and cardiovascular disorder: Renin plays an important role in blood pressure regulation, with experimental evidence that 1,25 dihydroxy vitamin D[1,25(OH)2D] inhibits renin synthesis in the kidney (20) and that vitamin D deficiency may stimulate the renin-angiotensin-aldosterone system (RAAS), increase angiotensin, atherosclerosis, and endothelial dysfunction, resulting in an increased risk of cardiovascular disease (21).