Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, 01246-904, Brazil.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, 02111, USA.
Eur J Nutr. 2019 Dec;58(8):3069-3077. doi: 10.1007/s00394-018-1852-5. Epub 2018 Nov 2.
The aim of this study was to investigate circulating folic acid (FA) and predict circulating FA concentrations in the population related to dietary intake, vitamin concentrations, and interaction with the genetic variants involved in folate metabolism.
Data were from the 'Health Survey of São Paulo' a cross-sectional population-based survey, conducted in São Paulo City, Brazil. The participants (n = 750) provided fasting blood samples and food intake data. Folate, homocysteine, and B6 and B12 vitamins were assayed. DNA was isolated, and the genotypes for polymorphisms involved in folate metabolism were determined. A generalized linear model was performed to predict circulating FA concentration.
The circulating FA was detected in 80.0% of the population, with a median concentration of 1.6 nmol/L (IQR 0.5-2.9). The increase of circulating FA concentrations was directly associated with total folate concentration (β coeff. 1.03; 95% CI 1.02-1.04), age (β coeff. 1.01; 95% CI 1.01-1.02), current smoker (β coeff. 1.51; 95% CI 1.16-1.97), self-reported skin color (β coeff. 1.83; 95% CI 1.51-2.20), as well as interaction between folate concentration and 19-bp deletion polymorphism in DHFR (β coeff. 1.02; 95% CI 1.01-1.03), and inversely associated with vitamin B6 (β coeff. 0.99; 95% CI 0.98-0.99).
In the current study, the presence of detectable circulating folic acid is high, and its concentration is elevated compared with other populations. Age, smoking, lower concentration of vitamin B6 and genetic variant are associated with increased levels of circulating FA. Further researches are needed to acknowledge and guarantee the safety of exposure to folic acid, especially in countries which have mandatory fortification.
本研究旨在调查循环叶酸（FA）并预测与饮食摄入、维生素浓度相关的人群中的循环 FA 浓度，以及与叶酸代谢相关的遗传变异的相互作用。
数据来自巴西圣保罗市进行的一项横断面人群为基础的“圣保罗健康调查”。参与者（n=750）提供了空腹血样和饮食摄入数据。检测了叶酸、同型半胱氨酸以及维生素 B6 和 B12。提取 DNA，并确定了参与叶酸代谢的多态性的基因型。采用广义线性模型预测循环 FA 浓度。
人群中 80.0%检测到循环 FA，中位数浓度为 1.6 nmol/L（IQR 0.5-2.9）。循环 FA 浓度的增加与总叶酸浓度呈直接相关（β 系数 1.03；95%CI 1.02-1.04），与年龄（β 系数 1.01；95%CI 1.01-1.02）、当前吸烟者（β 系数 1.51；95%CI 1.16-1.97）、自我报告的肤色（β 系数 1.83；95%CI 1.51-2.20）以及叶酸浓度与 DHFR 中 19-bp 缺失多态性之间的相互作用（β 系数 1.02；95%CI 1.01-1.03）呈正相关，与维生素 B6 呈负相关（β 系数 0.99；95%CI 0.98-0.99）。
在目前的研究中，可检测到的循环叶酸的存在率很高，其浓度与其他人群相比有所升高。年龄、吸烟、维生素 B6 浓度较低以及遗传变异与循环 FA 水平升高相关。需要进一步研究以确认并保证接触叶酸的安全性，特别是在强制进行营养强化的国家。
