Importantly, low levels of vitamin D may upregulate the renin-angiotensin-aldosterone system (RAAS) [28],which could stimulate collagen formation, matrix remodeling and vascular hypertrophy, increase oxidant stress, depress nitric-oxide-dependent signaling, and reduce elastin synthesis [29], leading to the development of atherosclerosis. This evidence concerns the gene REN and atherosclerosis.