Systematic review and bayesian meta-analysis of the dose-response relationship between folic acid intake and changes in blood folate concentrations

• Authors: Krista S. Crider, Centers for Disease Control and Prevention; Owen Devine, Emory University; Yan Ping Qi, Centers for Disease Control and Prevention; Lorraine F. Yeung, Centers for Disease Control and Prevention; Ahlia Sekkarie, Oak Ridge Institute for Science and Education; Ibrahim Zaganjor, Oak Ridge Institute for Science and Education; Eugene Wong, Oak Ridge Institute for Science and Education; Charles E. Rose, Centers for Disease Control and Prevention; Robert J. Berry, Centers for Disease Control and Prevention
• Journal Title: Nutrients
• Volume: Volume 11, Number 1
• Publisher: MDPI | 2019-01-01
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.3390/nu11010071
• Subjects: Health Sciences, Nutrition; Health Sciences, Epidemiology
• Keywords: folic acid; fortification; plasma folate; public health; red blood cell folate; serum folate; supplementation; Bayes Theorem; Dose-Response Relationship, Drug; Folic Acid; Food, Fortified; Humans; Nutritional Status

Abstract

The threshold for population-level optimal red blood cell (RBC) folate concentration among women of reproductive age for the prevention of neural tube defects has been estimated at 906 nmol/L; however, the dose-response relationship between folic acid intake and blood folate concentrations is uncharacterized. To estimate the magnitude of blood folate concentration increase in response to specific dosages of folic acid under steady-state conditions (as could be achieved with food fortification), a systematic review of the literature and meta-analysis was conducted. Of the 14,002 records we identified, 533 were selected for full-text review, and data were extracted from 108 articles. The steady-state concentrations (homeostasis) of both serum/plasma and RBC folate concentrations were estimated using a Bayesian meta-analytic approach and one-compartment physiologically-based pharmacokinetic models. RBC folate concentrations increased 1.78 fold (95% credible interval (CI): 1.66, 1.93) from baseline to steady-state at 375–570 µg folic acid/day, and it took a median of 36 weeks of folic acid intake (95% CI: 27, 52) to achieve steady-state RBC folate concentrations. Based on regression analysis, we estimate that serum/plasma folate concentrations increased 11.6% (95% CI: 8.4, 14.9) for every 100 µg/day folic acid intake. These results will help programs plan and monitor folic acid fortification programs.