Dietrich Marion, Brown Coralie J P, Block Gladys
School of Public Health, University of California-Berkeley, Berkeley, CA, USA.
J Am Coll Nutr. 2005 Aug;24(4):266-74. doi: 10.1080/07315724.2005.10719474.
Since January 1998, the Federal Drug Administration has required folic acid fortification of all enriched cereal-grain products in the U.S. This program intended to increase folic acid intake among women of childbearing age in order to decrease their risk of pregnancies affected by neural tube defects. The aim of this study was to explore the changes in serum and erythrocyte folate status of the adult U.S. population following folic acid fortification of enriched cereal-grain products and to explore accompanying changes in food sources and dietary total folate intake.
We compared data from two National Health and Nutrition Examination Surveys (NHANES): NHANES III, conducted during 1988 to 1994, reflecting the time prior to folate fortification, and NHANES 1999-2000, reflecting the time period after fortification.
Mandatory folic acid fortification led to significant increases in both serum and erythrocyte folate concentrations in all sex and age groups. In the overall study population the mean serum folate concentration increased more than two-fold (136%), from 11.4 nmol/L to 26.9 nmol/L, and the mean erythrocyte folate concentration increased by 57 percent, from 375 nmol/L to 590 nmol/L. Less than 10% of women of childbearing age reached the recommended erythrocyte folate concentration of greater than 906 nmol/L that has been shown to be associated with a significant reduction in neural tube defect (NTD) risk. After fortification, the category "bread, rolls, and crackers" became the single largest contributor of total folate to the American diet, contributing 15.6% of total intake, surpassing vegetables, which were the number one folate food source prior to fortification. Dietary intake of total folate increased significantly in almost all sex and age groups, except in females over 60 years of age. The mean dietary total folate intake of the study population increased by 76 microg/d (28%), from 275 microg/d to 351 microg/d.
The fortification of enriched cereal-grain products with folic acid led to a significant improvement of blood folate status of the overall adult, non-supplement using, US population. However, women of childbearing age may take folic acid supplements to reach erythrocyte folate levels that have been associated with decreased risk of NTDs.
自1998年1月起，美国联邦药物管理局要求对美国所有强化谷物类产品添加叶酸。该计划旨在增加育龄妇女的叶酸摄入量，以降低她们生育受神经管缺陷影响胎儿的风险。本研究的目的是探讨强化谷物类产品添加叶酸后美国成年人群血清和红细胞叶酸水平的变化，并探讨食物来源和膳食总叶酸摄入量的相应变化。
我们比较了两次美国国家健康和营养检查调查（NHANES）的数据：1988年至1994年进行的NHANES III，反映了叶酸强化之前的时期；以及1999 - 2000年的NHANES，反映了强化之后的时期。
强制性叶酸强化使所有性别和年龄组的血清和红细胞叶酸浓度均显著增加。在整个研究人群中，血清叶酸平均浓度增加了两倍多（136%），从11.4纳摩尔/升增至26.9纳摩尔/升，红细胞叶酸平均浓度增加了57%，从375纳摩尔/升增至590纳摩尔/升。不到10%的育龄妇女达到了推荐的红细胞叶酸浓度大于906纳摩尔/升，该浓度已被证明与神经管缺陷（NTD）风险显著降低相关。强化之后，“面包、面包卷和饼干”类别成为美国饮食中总叶酸的单一最大贡献者，占总摄入量的15.6%，超过了强化前作为首要叶酸食物来源的蔬菜。几乎所有性别和年龄组的膳食总叶酸摄入量都显著增加，60岁以上女性除外。研究人群的膳食总叶酸平均摄入量增加了76微克/天（28%），从275微克/天增至351微克/天。
强化谷物类产品添加叶酸使总体成年、不使用补充剂的美国人群的血液叶酸状况得到显著改善。然而，育龄妇女可能需要补充叶酸以达到与降低NTD风险相关的红细胞叶酸水平。
