Folate intakes of vegetarian and non vegetarian adolescent females

Abstract

Background: Folate is a water soluble B vitamin found naturally among food sources such as dark green vegetables, legumes, beans and offal such as liver. The synthetic form of folic acid is found in fortified food sources and supplements. Nationally and worldwide, folate is a nutrient of concern, as many populations consume intakes below the estimated average requirement. Thus, mandatory fortification of the food supply is common practice for many countries. New Zealand’s policy allows the voluntary fortification. It is unknown whether New Zealand adolescent females are achieving their recommended needs, particularly as dietary patterns change, such as increased consumption of plant-based diets. Objective: The objective of the present study was to evaluate the dietary intake of folate, and major food group contributors among a sample of adolescent vegetarian and non-vegetarian females in New Zealand. Design: This is a cross-sectional study designed as part of the larger Survey of Nutrition Dietary Assessment and Lifestyle (SuN DiAL) project. Healthy females between 15 to 18 years old were recruited in two phases from 13 high schools, and through targeted recruitment. Participant data were collected via two 24-hour diet recalls, anthropometric measurements, as well as, online sociodemographic and dietary questionnaires. Usual energy and folate intakes (total, natural food folate and folic acid), and the prevalence of folate inadequacy were assessed. Food consumption was categorised into 33 food groups and major contributors to folate intake were calculated. Results: Two-hundred and eighty-two participants enrolled in the study, with 250 participants completing one 24 hour recall; of those, 213 (85%) completed a second recall. The majority of participants identified as non-vegetarian, with 31 (12%) identifying as vegetarian. The average age of participants was 16.8 years; however, vegetarian participants were slightly older (17.1 years). Over three-quarters of participants were New Zealand European and Other, with approximately 16% of participants classified as Māori and a small proportion of Pacific and Asian participants. Dietary results showed median total intake of folate (IQR) was 306 (232.3, 409.5) µg dietary folate equivalents (DFEs)/day, with an estimated folic acid intake of 33 (0.0, 90.0) µg/day. Over half of all participants consumed folate intakes below the EAR. However, the usual folate intakes among vegetarians were higher, and prevalence of inadequacy was substantially lower than non-vegetarians (32 vs 61%, respectively), despite lower energy intakes among vegetarians. Moreover, folic acid intakes were higher among vegetarians. The major folate contributors for vegetarians were vegetables and bread, as for non-vegetarians the result was reversed. A slightly higher percentage of vegetarian participants were consuming food items from both food groups (87.1 and 83.9% for vegetables and bread, respectively). Conclusion: Results show that adolescent females, in general, continue to have a high prevalence of inadequate folate intakes although vegetarians had a lower risk of inadequacy compared to non-vegetarians. These findings are a concern as achieving optimal folate intakes are important for reproductive age women. Mandatory fortification has shown to be an effective intervention among this target group globally. More research is required to better understand the impact of increased voluntary fortification or a mandatory policy on the folate intakes of both New Zealand reproductive women and other population lifecycle groups.