Calcium intakes and the main food sources of calcium in New Zealand adolescent females

Abstract

Background: Adolescence is a critical time to be consuming adequate amounts of calcium for bone health. The consequences of inadequate calcium intake include reduced bone mass and increased risk of osteoporosis, a disease which decreases quality of life in older adults. Internationally, calcium intake among adolescent females is low with a high prevalence of inadequacy. Currently, limited data is available on calcium intakes of adolescent females aged 15-18 years in New Zealand.

Objective: To assess the intake of calcium and establish the prevalence of calcium inadequacy among New Zealand adolescent females aged 15-18 years old. Key food groups that contribute to calcium intake will also be examined.

Design: Phase one of the SuNDiAL study was a cross-sectional cluster study involving 145 participants aged 15-18 years old, from eight high schools across New Zealand. Online questionnaires collected self-reported data on demographic, and dietary food habits. Actual dietary intake was assessed using repeated 24-hour dietary recalls. The dietary assessment software FoodWorks was used to calculate calcium intake based on the New Zealand Food Composition Tables and was adjusted for usual intake using the multiple source method. The prevalence of calcium intake inadequacy was estimated using the estimated average requirement (EAR) cut-point method. Height and weight measurements were used to calculate body mass index Z-scores.

Results: The mean dietary calcium intake of adolescent females aged 15-18 years in New Zealand was low at 723 (95 % CI 677, 769) mg/day. Additionally, 89 % of the study population had inadequate calcium intakes. The most common food sources that contributed to calcium intake of the study cohort were milk (16 %), cheese (11 %), bread-based dishes (10 %), and bread (10 %). One fifth of participants reported consuming a plant-based milk while 18 % reported that they did not usually consume breakfast. Regular consumption of milk, fruit, vegetables, juice and breakfast had a significant positive relationship with calcium intake.

Conclusion: This study suggests that majority of adolescent females (89 %) are not consuming adequate intakes of dietary calcium, placing them at risk of osteoporosis in later life. Dietitians should be conscious of this when working with this population. Further research is recommended to examine if certain socio-economic or ethnic groups are particularly at risk. Additionally, barriers and facilitators to increase calcium intake in this population should be revised.