Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21287, USA.
Am J Epidemiol. 2010 Oct 15;172(8):932-41. doi: 10.1093/aje/kwq197. Epub 2010 Sep 16.
The authors' objective in this study was to estimate the changes in serum folate and homocysteine concentration that resulted from 6 weeks of supplementation with folic acid. A randomized, double-blind, placebo-controlled, dose-response trial with a parallel-group design was conducted. A total of 133 participants aged 60-90 years (70% female, 19% nonwhite) were assigned to receive 0, 100, 400, 1,000, or 2,000 μg/day of folic acid for 6 weeks. Data were collected in the United States between June and September 1996. At baseline, median serum folate and plasma homocysteine concentrations were 5.7 ng/mL (interquartile range (25th-75th percentiles), 4.1-7.8) and 8.3 μmol/L (interquartile range, 7.1-10.0), respectively. As the folic acid dose increased, serum folate levels increased (P-trend < 0.001). There was no dose-response relation with homocysteine level among all participants. In analyses restricted to persons with the lowest serum folate concentration (<4.5 ng/mL) at baseline, there was a trend (P = 0.06) toward decreased homocysteine levels with increasing folic acid dose. In healthy, older adults with adequate folate status, folic acid supplementation is not beneficial for homocysteine reduction. However, for older adults with low serum folate levels, supplementation will improve folate status and may be beneficial for lowering homocysteine concentrations.
作者在这项研究中的目的是估计补充叶酸 6 周后血清叶酸和同型半胱氨酸浓度的变化。采用随机、双盲、安慰剂对照、剂量反应试验和平行组设计进行了一项研究。共有 133 名年龄在 60-90 岁之间的参与者（70%为女性，19%为非白人）被分配接受 0、100、400、1000 或 2000μg/天的叶酸，持续 6 周。数据于 1996 年 6 月至 9 月在美国收集。在基线时，中位数血清叶酸和血浆同型半胱氨酸浓度分别为 5.7ng/ml（四分位间距（25%至 75%），4.1-7.8）和 8.3μmol/L（四分位间距，7.1-10.0）。随着叶酸剂量的增加，血清叶酸水平升高（P-趋势<0.001）。所有参与者中，同型半胱氨酸水平与叶酸剂量之间没有剂量反应关系。在对基线时血清叶酸浓度最低（<4.5ng/ml）的人进行的分析中，同型半胱氨酸水平随着叶酸剂量的增加而降低的趋势（P=0.06）。在叶酸状态充足的健康老年成年人中，叶酸补充对降低同型半胱氨酸没有益处。然而，对于血清叶酸水平较低的老年人，补充叶酸将改善叶酸状态，并可能有助于降低同型半胱氨酸浓度。
