Zinc status, dietary zinc intake and metabolic risk in Australian children and adolescents; Nepean Longitudinal Study

Purpose Zinc is essential for normal growth and metabolism. We aimed to characterise the total and bioavailable dietary zinc intake and plasma zinc concentrations in healthy children, longitudinally, and to examine the association between plasma zinc concentrations, dietary zinc intake and cardiometabolic markers in the same cohort. Methods A secondary data analysis of a prospective cohort study, the Nepean Longitudinal Study, which followed an Australian birth cohort at ages 8 (n = 436) and 15 years (n = 290) collecting dietary, anthropometry and biochemistry data (plasma zinc, fasting glucose, insulin and lipid profile). Diet was assessed by a 3-day food record and a food frequency questionnaire at 8 and 15 years, respectively. Zinc bioavailability was determined by the phytate/zinc molar ratio. Results At 8 years, the median zinc intake was 7.84 mg (interquartile range 6.57-9.35) for boys and 7.06 mg (5.98-8.30) for girls. Three of 345 children reported inadequate absorbable zinc intake, and none reported inadequate total zinc intake. At 15 years, median zinc intake was 11.8 mg (9.41-14.8) for boys and 8.54 mg (6.76-10.7) for girls. The prevalence of inadequate intakes of absorbable zinc and total zinc was 19 and 29 %, respectively. Plasma zinc concentration was not correlated with dietary zinc intake, adiposity nor lipids at either time point, but it was inversely correlated with fasting glucose at 8 year and with insulin at 15 years. Conclusions Australian children had an overall adequate zinc status. However, adolescents who reported suboptimal dietary zinc intakes were more likely to have raised insulin concentrations.