Iron status and cardiovascular disease risk in black South African women: the PURE study

Abstract

Objective: To examine the associations between measures of iron status and cardiovascular disease (CVD) risk factors in South African women. Method: In a cross-sectional study, demographic information and health history were obtained during individual interviews using validated questionnaires in the North West Province, South Africa. Anthropometric indices, iron indices, blood pressure, blood glucose and lipid profiles were measured using standard procedures in 1 262 apparently healthy black South African women aged 35 years or older. Iron status was assessed using serum concentrations of ferritin, transferrin receptor (TfR) and TfR:ferritin ratio. Results: Associations between iron status parameters and CVD risk factors were generally weak (r < 0.3, p < 0.01) and were not retained when adjustment was made for age, body mass index, smoking, alcohol consumption and C-reactive protein in the analysis. Waist circumference (WC) and waist:hip ratio (WHR) were higher in the fourth quartile of serum ferritin than in the third quartile, and also in the third quartile compared to the second quartile (P < 0.05). Based on WC and WHR respectively, 31% and 52% of the women had excess abdominal obesity. The mean (95% confidence interval) serum TfR concentration was high, at 9.09 ?g/ml (8.77, 9.44), indicating risk of iron deficiency. The mean (95% confidence interval) concentrations of lipids [total cholesterol 4.78 mmol/l (4.64, 4.93), high-density lipoprotein cholesterol 1.45 mmol/l (1.39, 1.52), low-density lipoprotein cholesterol 1.65 mmol/l (1.53, 1.78), triglyceride 1.12 mmol/l (1.07, 1.18)] were within reference ranges. Conclusion: No significant association was found between iron status parameters and established CVD risk factors. However, excessive abdominal adiposity indicated by high WC and WHR contributes significantly to increased serum ferritin concentration in this population.