Cuskelly G J, McNulty H, Scott J M
Northern Ireland Centre for Diet and Health, University of Ulster, Coleraine, Northern Ireland, United Kingdom, and the Department of Biochemistry, Trinity College, Dublin, Ireland.
Am J Clin Nutr. 1999 Aug;70(2):234-9. doi: 10.1093/ajcn.70.2.234.
Mandatory fortification of grain products with folic acid was introduced recently in the United States, a policy expected to result in a mean additional intake of 100 microgram/d. One way of predicting the effectiveness of this measure is to determine the effect of removing a similar amount of folic acid as fortified food from the diets of young women who had been electively exposed to chronic fortification.
The objective was to examine the effect on folate status of foods fortified with low amounts of folic acid.
We investigated the changes in dietary intakes and in red blood cell and serum concentrations of folate in response to removing folic acid-fortified foods for 12 wk from the diets of women who reportedly consumed such foods at least once weekly (consumers).
Consumers (n = 21) had higher total folate intakes (P = 0.002) and red blood cell folate concentrations (P = 0.023) than nonconsumers (women who consumed folic acid-fortified foods less than once weekly; n = 30). Of greater interest, a 12-wk intervention involving the exclusion of these foods resulted in a decrease in folate intake of 78 +/- 56 microgram/d (P < 0.001), which was reflected in a significant reduction in red blood cell folate concentrations (P < 0.05).
Cessation of eating folic acid-fortified foods resulted in removing 78 microgram folic acid/d from the diet. Over 12 wk this resulted in a lowering of red blood cell folate concentrations by 111 nmol/L (49 microgram/L). This magnitude of change in folate status in women can be anticipated as a result of the new US fortification legislation and is predicted to have a significant, although not optimal, effect in preventing neural tube defects.
美国最近开始强制要求在谷物产品中添加叶酸，预计这一政策将使平均每日额外摄入量增加100微克。预测这一措施有效性的一种方法是，确定从长期选择性摄入强化食品的年轻女性饮食中去除与强化食品中叶酸含量相似的量后所产生的影响。
本研究旨在探讨低叶酸强化食品对叶酸水平的影响。
我们调查了据报道每周至少食用一次此类食品（食用者）的女性，在从其饮食中去除叶酸强化食品12周后，膳食摄入量以及红细胞和血清叶酸浓度的变化。
与非食用者（每周食用叶酸强化食品少于一次的女性；n = 30）相比，食用者（n = 21）的总叶酸摄入量（P = 0.002）和红细胞叶酸浓度更高（P = 0.023）。更值得关注的是，一项为期12周、涉及排除这些食品的干预措施导致叶酸摄入量减少了78±56微克/天（P < 0.001），这反映在红细胞叶酸浓度显著降低（P < 0.05）。
停止食用叶酸强化食品导致饮食中每日减少78微克叶酸摄入。在12周内，这使得红细胞叶酸浓度降低了111纳摩尔/升（49微克/升）。美国新的强化立法预计会导致女性叶酸水平出现这种程度的变化，并预计在预防神经管缺陷方面会产生显著（尽管并非最佳）效果。
