脑卒中已成为我国首位死因，脑卒中具有高发病率、高死亡率、高致残率、高复发率的特点。高血压合并高同型半胱氨酸（H型高血压）是我国脑卒中高发的重要危险因素，在降压基础上再降同型半胱氨酸明显减少脑卒中发生风险，补充叶酸可使血同型半胱氨酸水平下降。经研究发现，亚甲基四氢叶酸还原酶基因多态性对叶酸补充有修饰作用，不同基因型的高血压患者补充同等剂量叶酸后脑卒中下降率不同，TT基因获益更大，但不同基因型患者所需的最佳叶酸剂量尚不清楚。本研究拟采用多中心、随机双盲对照临床试验，按基因型（CC、CT、TT）分组，分别给予不同剂量叶酸观察不同基因型高血压患者间血压、同型半胱氨酸、叶酸量效关系，以评价和比较不同基因型高血压人群中补充不同剂量叶酸，降低血浆Hcy水平和升高血清叶酸水平效果方面的差异，探寻不同基因型患者最佳叶酸补充剂量，从而为临床实践和公共卫生方面精准控制H型高血压、更有效预防脑卒中发生提供重要依据

Stroke ranks first among all of the causes of death in China, and is recognized as a disease with high incidence, fatality, disability, and recurrence rate. Hypertension with high homocysteine (H-type hypertension) is an important risk factor for stroke among Chinese population, and lowering homocysteine level with lowering blood pressure together could reduce the risk of stroke effectively. Folic acid supplementation could lower homocysteine level in blood plasma.Previous studies indicated that MTHFR C677T genetic polymorphism may modified the effect of folic acid supplementation, so that the H-type hypertension patients with various genotypes may benefit differently from folic acid supplementary.However, it is still not clear of the most effective dose of folic acid supplementation for patients with different genotypes. This study aims to explore the optimal folic acid supplementation doses for the H-type hypertension patients with various genotypes, by investigating the dose-response relationship between folic acid supplementation doses, and hypertension control outcomes (the level of blood pressure and homocysteine), through a double-blind, randomized controlled, multicenter Clinical Trial. Furthermore, we intend to provide evidence for precise control of H-type hypertension and more effective stroke prevention in public health and clinical practices.