Vitamin B12 intakes of vegetarian and non-vegetarian adolescent females
Background: The adoption of plant-based diets for reasons of health and sustainability is becoming increasingly popular especially among the younger generation. Indeed, reducing meat consumption has been associated with favourable health benefits; however, certain nutrients such as vitamin B12 are naturally found mostly in animal-based foods, and thus individuals who follow vegetarian eating patterns without proper planning are at risk of dietary inadequacies. Adolescence is a life stage where rapid physical and social development takes place leading to an increase in nutrient requirements alongside social pressures which can play a major role in eating behaviours. These factors can result in an unbalanced diet among adolescents. Therefore, monitoring changes in dietary patterns and assessing nutritional status of at risk life stage groups are important. To date, there is limited information on the dietary intakes of adolescent females in New Zealand, particularly among those adopting vegetarian diets. Objective: The aim of the study was to assess the dietary intake and adequacy of vitamin B12 among a group of vegetarian and non-vegetarian adolescent females aged 15-18 years. In addition, we also explored the major food group contributors to vitamin B12 intakes among these groups of adolescents with distinct dietary patterns. Design: This study was a cross-sectional survey in which school-based recruitment and targeted recruitment of 15-18 year old adolescent females were conducted, from 13 high schools of different deciles across New Zealand, and vegetarians and vegans in Dunedin, respectively. Questionnaires capturing information such as sociodemographic and health were completed by the participants. Anthropometric measurements for calculation of BMI, and two 24-hour diet recalls for estimation of usual intake were collected. Dietary data including energy and vitamin B12 intakes were analysed using FoodWorks – a nutrient analysis software programme using data from the New Zealand Food Composition Tables (NZFCT) – and major food group contributors of vitamin B12 intakes were ranked. Results: In total, 251 adolescent females provided dietary intake data. Of those who participated, 36 (13%) self-identified as vegetarian with the remaining participants reporting being non-vegetarian. The majority of participants were New Zealand European and others (NZEO) and were living in low to moderate deprived areas. Two-thirds of participants were 17-18 years old and had a healthy BMI. The mean usual vitamin B12 intakes of vegetarians and non-vegetarians were 1.4 μg/day and 2.8 μg/day, respectively. The risk of inadequate vitamin B12 intake among vegetarians (74%) are higher than non-vegetarians (14%). with the prevalence of B12 inadequacy of 74% and 14%, respectively. Milk was shown to be the common major food group contributing towards the total vitamin B12 intake of vegetarians and non-vegetarians. Other major contributing food groups of vitamin B12 are savoury sauces and condiments (included yeast extract, milk/cheese sauces, mayonnaise) for vegetarians, and beef and veal for non-vegetarians. Conclusion: In summary, adolescent females are at risk of inadequate vitamin B12 intake with vegetarians presenting with a significantly higher prevalence of inadequacy when compared with non-vegetarians. This is a concern with the increasing adoption of vegetarian eating patterns. Future research such as national nutrition surveys are needed to track dietary patterns and assess the risk of inadequate intakes as verified by appropriate biomarkers.
Advisor: Houghton, Lisa
Degree Name: Master of Dietetics
Degree Discipline: Department of Human Nutrition
Publisher: University of Otago
Keywords: New Zealand; adolescent; females; vegetarian; non-vegetarian; vitamin b12; intake
Research Type: Thesis