Rydlewicz A, Simpson J A, Taylor R J, Bond C M, Golden M H N
Department of General Practice and Primary Care, University of Aberdeen, Aberdeen, UK.
QJM. 2002 Jan;95(1):27-35. doi: 10.1093/qjmed/95.1.27.
Increased plasma homocysteine is associated with coronary artery disease, peripheral vascular disease and venous thrombosis. Folic acid is the most effective therapy for reducing homocysteine levels. The lowest effective supplement of folic acid is not known, particularly for the elderly who have the highest prevalence of these conditions.
To explore the effects of daily supplements of 0, 50, 100, 200, 400 and 600 microg folic acid on plasma homocysteine in an elderly population.
Randomized double-blind placebo-controlled trial.
Participants (n=368) aged 65-75 years were randomly allocated to receive one of the treatments for 6 weeks. Plasma homocysteine was recorded after 3 weeks and 6 weeks of supplementation.
Only the 400 microg and 600 microg groups had significantly lower homocysteine levels compared to placebo (p=0.038 and p<0.001, respectively). Using multiple linear regression and each individual's total folic acid intake (diet plus supplement), a total daily folic acid intake of 926 microg per day would be required to ensure that 95% of the elderly population would be without cardiovascular risk from folate deficiency.
A daily folic acid intake of 926 microg is unlikely to be achieved by diet alone. Individual supplementation or fortification of food with folic acid will be required to reach this target.
血浆同型半胱氨酸水平升高与冠状动脉疾病、外周血管疾病及静脉血栓形成相关。叶酸是降低同型半胱氨酸水平最有效的疗法。尚不清楚叶酸的最低有效补充量，尤其是在这些疾病患病率最高的老年人中。
探讨每日补充0、50、100、200、400和600微克叶酸对老年人群血浆同型半胱氨酸的影响。
随机双盲安慰剂对照试验。
将368名年龄在65 - 75岁的参与者随机分配接受其中一种治疗，为期6周。在补充叶酸3周和6周后记录血浆同型半胱氨酸水平。
与安慰剂相比，仅400微克和600微克组的同型半胱氨酸水平显著降低（分别为p = 0.038和p < 0.001）。使用多元线性回归及每个人的总叶酸摄入量（饮食加补充剂），每天需要926微克的总叶酸摄入量才能确保95%的老年人群不会因叶酸缺乏而面临心血管风险。
仅通过饮食不太可能达到每天926微克的叶酸摄入量。需要进行个体补充或用叶酸强化食物才能达到这一目标。
