FOLIC ACID ON PLASMA TOTAL HOMOCYST(E)INE: MULTI VITAMIN USE & MTHFR GENOTYPES

血浆总同型半胱氨酸（tHcy）浓度升高是一种 动脉闭塞性疾病的常见危险因素。 叶酸（FA） 补充通常会降低tHcy水平，但初始tHcy和 维生素水平，多种维生素的使用，以及基因多态性， 5，10-亚甲基四氢叶酸还原酶（MTHFR）可能有助于 减少的可变性。 我们测试了30周每天 摄入1或2 mg FA补充剂对患者tHcy水平的影响 和无冠心病（CHD）的患者进行分析， C677 T MTHFR突变。 既往多种维生素摄入和基线维生素 和tHcy水平也与叶酸的反应性进行了比较 补充。 两种剂量的FA降低tHcy水平相似， 无论性别、年龄、CHD状态、体重指数、吸烟或 血浆肌酐浓度。 在非复合维生素使用者中，FA 补充剂使C/C纯合子的tHcy降低7%，使C/C纯合子的tHcy降低13%或21%。 分别具有一个或两个T677等位基因拷贝的受试者; 使用多种维生素的人相应减少的幅度较小。 T/T纯合子tHcy升高， 在血浆叶酸水平略低时对高水平tHcy的敏感性 水平，以及增强对降低tHcy作用的反应， FA. 虽然其他因素可能参与了 tHcy水平对FA补充的反应性，约三分之一 的反应性异质性可归因于基线tHcy 和叶酸水平以及多种维生素的使用。

Elevated concentration of plasma total homocyst(e)ine (tHcy) is a common risk factor for arterial occlusive diseases. Folic acid (FA) supplementation usually lowers tHcy levels, but initial tHcy and vitamin levels, multivitamin use, and polymorphisms in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) may contribute to variability in reduction. We tested the effects of a 30 week daily intake of 1 or 2 mg of FA supplements on tHcy levels in patients with and without coronary heart disease (CHD) who were analyzed for the C677T MTHFR mutation. Prior multivitamin intake and baseline vitamin and tHcy levels were also compared with responsiveness to folate supplementation. Both dosages of FA lowered tHcy levels similarly, regardless of sex, age, CHD status, body mass index, smoking, or plasma creatinine concentration. In non-multivitamin users, FA supplements reduced tHcy by 7% in C/C homozygotes and by 13% or 21% in subjects with one or two copies of the T677 allele, respectively; the corresponding reductions were smaller in users of multivitamins. Moreover, T/T homozygotes had elevated tHcy and increased susceptibility to high levels of tHcy at marginally low plasma folate levels, as well as enhanced response to the tHcy-lowering effects of FA. Although other factors are probably involved in the responsiveness of tHcy levels to FA supplementation, about one third of heterogeneity in responsiveness was attributable to baseline tHcy and folate levels and to multivitamin use.