Abstract
Background: Folate is a B vitamin that plays a vital role in the synthesis and methylation of DNA and, thus, is essential for optimal growth and development. The recommended folate intake for adolescent males is difficult to meet solely through the daily consumption of natural folate-containing food sources. Fortification of food with folic acid, the synthetic form of folate, is one way to remedy this situation. New Zealand’s policy permits voluntary fortification of folic acid to certain foods, mainly breakfast cereals and breads, with an increase in fortification of breads over the several years. The impact of folic acid fortification on the usual total folate intake of New Zealand adolescent males (the highest consumers of bread), however, is unknown.
Objective: The present study aimed to evaluate the usual folate intake and adequacy of a group of adolescent males aged 15-18 years in New Zealand and determine the major food group contributors of total folate, natural folate and folic acid.
Methods: This study was a cross-sectional survey of 135 New Zealand male adolescents aged 15-18 years old recruited through six high schools between February and April 2020. Sociodemographic and dietary habits (including supplement use) were collected via online questionnaires, and body weight and height were measured. Dietary intake was assessed via two non-consecutive 24-hour dietary recalls (n=102) using the multiple pass method. Daily usual folate intakes (natural food folate, folic acid and total folate intake as Dietary Folate Equivalents, DFEs) adjusted for within-person variability were estimated using FoodWorks9 comprised of the most up-to-date New Zealand food composition tables (FOODfiles 2018). The prevalence of inadequate folate intake was determined using the Estimated Average Requirement (EAR) cut-point method. The percentage contribution of folate (as natural folate, folic acid and total folate) from 33 designated food group to total folate intake were calculated and presented as the top ten food sources.
Results: The usual median (IQR) total folate intake of the population (in DFEs) was 454 (334, 715) μg/day comprised of 260 (207, 305) μg/day of natural food folate and 77 (0, 226) μg/day of folic acid intake. The prevalence of inadequate folate intake was considerably high (25%) despite greater folate intake than reported in the last national nutrition survey in 1997. No participant exceeded the Tolerable Upper Intake Level (UL) of folic acid. Asian participants had the highest prevalence of inadequacy (35%) compared to Pacific (33%), Māori (29%) and NZEO participants (19%). The percentage of participants with inadequacy varied among age groups with the prevalence being highest for the 16-year olds. The risk of inadequacy was also slightly lower among obese participants (20%) compared to normal weight (26%) or overweight (24%) but did not appear to differ among socioeconomic deprivation levels. Breakfast cereals were the highest contributor to total folate intake (25%) among New Zealand male adolescents, followed by breads (17%). Both of these food groups contain folic acid fortified products, and as such, these two food groups contributed almost 50% of the total intake of folic acid among the sample population.
Conclusion: Despite increased folic acid fortification in the food supply, New Zealand adolescent males are at risk of inadequate folate intake, particularly among certain ethnic groups. Total folate intakes in the present study appear to have increased among our sample population group compared to past national nutrition surveys, yet the prevalence of inadequacy remains a concern. Consideration of mandatory folic acid fortification is warranted given the demonstrated success in other countries to effectively improve the folic acid intake across the lifecycle of the population. Nonetheless, national nutrition survey data representative of the population food and folate intake is needed to better assess food fortification policies, including potential fortification vehicles.