Iron deficiency and risk factors in pre-menopausal females living in Auckland, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand

Abstract

Background: Iron Deficiency (ID) is the most common nutrient deficiency worldwide, affecting one third of the world’s population. In New Zealand (NZ), the highest rates are found within pre-menopausal females, with previously identified risk factors for ID including low meat intake, heavy menstruation and blood donation. Emerging risk factors such as inflammation and obesity are yet to be explored in NZ, along with the master hormone of iron regulation, hepcidin. Objectives: To describe iron and hepcidin status within premenopausal females, and identify risk factors for ID. Methods: Females (n=170) aged 18–45 were recruited. Biomarkers of iron status were measured: Serum ferritin (Sf), haemoglobin, soluble transferrin receptor, hepcidin as well as inflammatory markers C-reactive protein and interluekin-6. Body composition was measured using bioelectrical impedance analysis, and lifestyle factors were assessed using questionnaires, including a previously validated food frequency questionnaire. Variables known to potentially influence iron status were entered into multiple linear regression analysis to identify predictors of Sf. Results: Iron deficiency was confirmed in 55.8% of participants (Sf < 30µg·L-1). Prevalence of ID did not differ significantly (p=0.141) between South Asians (64.3%), NZ Europeans (51.6%), and those of other ethnicities (45.5%). Hepcidin concentrations were higher in those who were iron sufficient (Sf ≥ 30µg·L-1) (6.62nM vs 1.17nM, p<0.001). South Asian females had higher hepcidin (8.78nM) concentrations, compared to NZ Europeans (6.28nM) and those of other ethnicities (4.89nM) (p=0.026). The higher hepcidin concentrations in South Asian participants are possibly associated with these participants having a higher BMI (p<0.001), body fat percentage (p<0.001) and interlukein-6 (p<0.001) than NZ Europeans and other ethnicities. Hepcidin (β=0.082, p<0.001) and frequency of meat intake (β=0.058, p=0.001) were identified as significant predictors of Sf in NZ Europeans. Hepcidin was the only identified predictor of Sf in South Asians (β=0.138, p<0.001) and those of other ethnicities (β=0.117, p<0.002). Conclusion: The study confirms a positive relationship between hepcidin and Sf in NZ females, highlighting hepcidin’s potential as an emerging biomarker to identify ID. Furthermore, there were differences in hepcidin levels between ethnicities, which may be linked to higher levels of body fat and inflammation.