Zahedan Journal of Research in Medical Sciences Journal homepage: www.zjrms.ir

Nowadays, hypertension is one of the most important causes of death all over the world because of its adverse effects on cardiovascular system. For this reason its study is very valuable. Vitamin D is one of the important factors that may influence blood pressure. Many studies have shown the modulatory effect of this vitamin on rennin-angiotensin system as well as its inhibitory effect on vascular smooth muscle hypertrophy. According to the fact that vitamin receptors are distributed in almost all organs of human body, we can't consider its role just as factor in calcium homeostasis. Therefore many other important roles could be attributed to it. So vitamin D deficiency could arise many problems. There are many causes for vitamin D deficiency. The most important is insufficient exposure to UV-B. In epidemiological studies the vitamin D deficiency is considered to be associated with high blood pressure, as emphasized in many cross-sectional studies. Concerning the cohort prospective studies, the relationship between vitamin D deficiency and hypertension is reported in some cases. The interventional studies about the association between vitamin D and hypertension are not many and the results are different or contradictory. Controversial results might be due to differences in dose of supplements or duration of supplement therapy. The aim of this systematic review is to assess the researches about the association between vitamin D deficiency and hypertension and discuss the power of them. This can be helpful to lighten the path to prospective investigations