Folate and Vitamin B12 Usual Intake and Biomarker Status in U.S. Adults: National Health and Nutrition Examination Survey (NHANES) 2007–2018

Abstract

Abstract Objectives There are 3 major folic acid intake sources in the US—enriched cereal grain products (ECGP), ready-to-eat cereals (RTE), and folic acid containing supplements (SUP), generating 4 mutually exclusive consumption groups. This study aims to describe the contribution of these sources to folic acid intakes above the tolerable upper intake level (UL, 1000 mg/d), and their impact on red blood cell (RBC) folate and serum vitamin B12 concentrations. Methods We used data for nonpregnant US adults (≥19 y) from the National Health and Nutrition Examination Survey (NHANES) 2007–2018 (n = 31,128); serum vitamin B12 data were only available for 2011–2014 (n = 9,298). Median usual intake was estimated from two 24-h dietary recalls using the National Cancer Institute (NCI) method. Statistical analyses accounted for complex survey design using appropriate weights. Results The proportions of those who consumed folic acid from ECGP only, ECGP +RTE, ECGP +SUP, and ECGP +RTE +SUP were 50%, 18%, 22%, and 10%, and the median modelled usual folic acid intakes (mg/d) were 126 (interquartile range (IQR): 92,168), 308 (IQR: 267, 360), 490 (IQR: 347, 586), and 687 (IQR: 577, 767), respectively. Overall, 1.97% (95% CI: 1.96%, 1.98%) of adults consumed >UL. Adults who did not consume SUP did not have intakes >UL. The median usual vitamin B12 intake was 6.4 (IQR: 4.1, 11.7) mg/d. Consumption of RTE and/or SUP was associated with higher RBC folate concentrations (nmol/L) (ECGP only: 976 [95% CI: 963, 989], ECGP +RTE: 1130 [95% CI: 1110, 1150], ECGP +SUP: 1307 [95% CI: 1283, 1332], ECGP +RTE +SUP: 1467 [95% CI: 1439, 1495]). Serum vitamin B12 concentrations (pmol/L) were 350 (95% CI: 343, 356; ECGP only), 380 (95% CI: 366, 393; ECGP +RTE), 456 (95% CI: 440, 473; ECGP +SUP), and 485 (95% CI: 462, 509; ECGP +RTE +SUP). RBC folate deficiency (<305 nmol/L) was < 2% and vitamin B12 deficiency (<148 pmol/L) was < 6% across all folic acid consumption groups. Conclusions Folate and vitamin B12 deficiencies are low in the US population. At current fortification levels, US adults who do not consume supplements do not have usual folic acid intake exceeding the UL. Vitamin B12 intake among most US adults meets the recommended daily allowance (2.4 mg/d). Funding Sources This project was conducted with no specific support..