Population-level changes in folate intake by age, gender, and race/ethnicity after folic acid fortification

Abstract

Objectives: We sought to quantify the impact of the 1998 US Food and Drug Administration (FDA) folic acid fortification policy by estimating folate intake at the population level.

Methods: We analyzed total folate intake levels (from food and supplements) according to gender, age, and race/ethnicity, using data from 2 National Health and Nutrition Examination Surveys. We measured pre- and postfortification folate intake distributions, adjusted for measurement error, and examined proportions of the population who reached certain thresholds of daily total folate intake.

Results: Mean daily food and total folate intake increased by approximately 100 microg/day after fortification. The proportion of women aged 15-44 years who consume more than 400 microg/day of folate has increased since fortification, but has not yet reached the FDA's 50% target and varies by race/ethnicity from 23% to 33%. Among persons aged 65 years and older who may be at risk for masking a vita-microg/day (the min B12 deficiency, the percentage who consume more than 1000 "tolerable upper intake level") has at least doubled among Whites and Black men, but has remained less than 5% for all groups.

Conclusions: Since fortification, folic acid intake among the US population has increased, and there are substantial variations by age, gender, and race/ethnicity.

FIGURE 1—

Daily total folate intake distributions, pre- and postfortification, for non-Hispanic White men (a), non-Hispanic White women (b), non-Hispanic Black men (c), non-Hispanic Black women (d), Mexican American men (e), and Mexican American women (f), corrected for measurement error. Includes folate consumption from all food and supplement sources, with food data adjusted for measurement error. Points represent midpoints of categories, and plots are smoothed between points. Upper endpoint of 1600 μg/day represents all intake more than 1500 μg/day.

FIGURE 2—

Total folate intake medians, pre- and postfortification, for men (a) and women (b) aged ‡15 years. Medians are presented by cohort and race/ethnicity, and includes folate consumption from all food and supplement sources. The effect of fortification was found to be highly significant (P < .001), after control for age, age-squared, gender, and race/ ethnicity. The effect of age varied significantly by race/ethnicity and gender, and the effect of gender varied significantly by race/ethnicity.

FIGURE 3—

Percentage of population taking supplements that contain folic acid, pre- and postfortification, among men (a) and women (b). The change after fortification was significant and dependent on age (P< .001) and race (P< .05), after control for age, age-squared, gender, race/ethnicity, and the interaction between gender and race/ethnicity.