Unmetabolized folic acid in serum: Acute studies in subjects consuming fortified food and supplements
Unmetabolized folic acid in serum: Acute studies in subjects consuming fortified food and supplements
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DOI：
10.1093/ajcn/65.6.1790
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发表时间：
1997-06-01
影响因子：
7.1
通讯作者：
Scott, JM
中科院分区：
文献类型：
--
作者：
Kelly, P;McPartlin, J;Scott, JM
围孕期摄入叶酸已被证明可以降低神经管缺陷的发生率。在主食中普遍强化叶酸的策略提出了终生接触未代谢叶酸的可能性。循环中暴露于叶酸的主要风险是掩盖恶性贫血中钴胺素缺乏症和神经系统疾病进展的诊断。其他影响尚不清楚。例如，从未在群体水平上研究过成人和胎儿细胞体内长期暴露于维生素合成形式的影响。这项研究检查了年轻和老年志愿者食用某些强化食品后血清中未代谢叶酸的急剧出现。除正常饮食外，接受 5 天强化即食谷物和面包治疗的受试者每餐摄入叶酸的阈值为 266 微克，此时血清中出现未改变的叶酸。通过等渗盐水、牛奶或白面包摄入叶酸的受试者的阈值也 > 200 微克。从美国的食品消费模式来看，假设全天消费，实施 1.4 毫克/千克的面粉强化不太可能导致血清中出现叶酸。然而，正如一些机构所提倡的那样，增加这种强化水平可能会导致多年来血清中反复出现叶酸，特别是对于大量摄入强化食品的非目标人群的消费者来说。美国食品和药物管理局规定的“安全摄入量”为每天 1 毫克叶酸可能会导致血清叶酸效应。此外，许多遵循每天服用400微克叶酸以预防神经管缺陷发生的建议的女性可能会出现反复的血清叶酸反应。
Periconceptual consumption of folic acid has been shown to decrease the incidence of neural tube defects. The strategy of universal fortification of staple foodstuffs with folic acid presents the possibility of life-long exposure to unmetabolized folic acid. Chief among the risks of exposure to folic acid in the circulation is that of masking the diagnosis of cobalamin deficiency in pernicious anemia and the progression of neurologic disease. Other effects are unknown. For instance, the effect of in vivo chronic exposure of adult and fetal cells to the synthetic form of the vitamin has never been investigated at the population level. This study examined the acute appearance of unmetabolized folic acid in serum in response to the consumption of some fortified foodstuffs by young and elderly volunteers. Subjects on a 5-d regimen of fortified ready-to-eat-cereal and bread in addition to their normal diet had a threshold intake of 266 mu g folic acid per meal at which unaltered folic acid appeared in the serum. Subjects given folic acid in either isotonic saline, milk, or white bread also had a threshold > 200 mu g. From patterns of food consumption in the United States, the implementation of flour fortification at 1.4 mg/kg is unlikely to lead to folic acid appearance in serum, assuming that consumption is spread throughout the day. Increasing this level of fortification, however, as has been advocated by some agencies, may result in the repeated appearance of folic acid in serum over many years, particularly in consumers in nontargeted populations of large amounts of fortified foods. The ''safe level of intake'' of 1 mg folate/d set by the US Food and Drug Administration may cause a serum folic acid effect. Furthermore, a repeated serum folic acid response is likely to be found in many women complying with the advice to take 400 mu g folic acid/d to prevent the occurrence of neural tube defects.