Fibre Intakes and the Main Food Sources of Fibre in Adolescent Males

Abstract

Background: Based on the 2008/09 New Zealand Adult Nutrition Survey, the mean dietary fibre intake in adolescent males aged between 15 and 18 years was at 21.9 grams (g) per day, which was well below the adequate intake (AI) for their age group of 28 g/day. Given the role of dietary fibre in promoting optimal health as well as the potential of changing dietary patterns and food sources over time, an update on the dietary fibre intakes of New Zealand adolescent males is warranted.

Objective: To determine the current mean intake of dietary fibre and the main food sources of fibre in New Zealand adolescent males aged between 15 and 18 years.

Methods: The Survey of Nutrition Dietary Assessment and Lifestyle (SuNDiAL) study is an ongoing clustered, cross-sectional survey in New Zealand that began in 2019. The data presented in this thesis were collected between February and April 2020. Male participants were enrolled from 6 high schools nationwide in Otago, Wellington, Christchurch, Rotorua, Tauranga and Auckland. High schools were selected based on a student roll of at least four hundred. Socio- demographics and bowel habits were self-reported with an online questionnaire. Height and weight were measured, and a Body Mass Index z-score was generated for each participant. Dietary data were assessed via two interviewer-led 24-hour multi-pass dietary recalls on non-consecutive days. The dietary data entered into FoodWorks 9 (Xyris Software, Australia) were used to estimate mean energy and fibre intakes for each participant. These were adjusted for within-person variation using a Multiple Source Method (MSM) program to represent usual intakes. The proportion of total fibre intake provided from the 33 food groups was estimated using Stata Statistical Analysis Software 16.0 (StrataCorp, Texas).

Results: One hundred and thirty-five male participants enrolled in our study. One hundred and two of those completed one 24-hour recall and seventy-two completed a second recall. Overall, the mean fibre intake was at 24.1 g/day (95% CI: 22.2, 25.9), which was lower than the AI of 28 g/day. Bread was the single largest food source of fibre intake contributing to eighteen percent, with thirty-nine percent of the male participants consuming white bread, followed by grains and pasta, and fruits at almost twelve percent and vegetables at eleven percent. Only one hundred and twenty-nine male participants completed the bowel habits questionnaire. Fifty percent of the male participants had bowel movements of either 5, 6 or 7 times a week, with the greatest frequency at 7 times a week, and sixty-eight percent had a Type 3 stool type on the Bristol Stool Chart, indicating regular bowel habits with a normal stool consistency among the adolescent male population.

Conclusion: The mean dietary fibre intake of this convenience sample of adolescent schoolboys was lower than the recommended. Given the influence of dietary fibre on optimal health promotion and chronic disease prevention, encouraging and supporting the adolescent male population to increase fibre-dense foods and whole grains consumption in accordance with the New Zealand dietary guidelines may help in achieving their AI for dietary fibre.