Associations between indices of iron status, anthropometric and biological markers of cardiovascular disease risk

Abstract

Background: In South Africa, as in many other developing countries, iron deficiency (the most common micronutrient deficiency) still remains unresolved; while obesity has emerged as a public health challenge causing increases in the incidence and prevalence of cardiovascular diseases (CVDs). Research has shown that certain iron indices are associated with both anthropometric and biological markers of CVDs. Adiposity is thought to modulate the pathway linking iron status to CVDs. Objective: To examine the associations between iron indices, anthropometric and biological markers of CVDs in an African population undergoing transition. Methods: This thesis was based on secondary analysis of data generated during the Transition and Health during Urbanisation of South Africans (THUSA) study; and primary and secondary analysis of the baseline Prospective Urban and Rural Epidemiological (PURE) study. Both studies were cross–sectional in design and were conducted between 1996–1998 and in 2005 respectively in the North West Province of South Africa. The 1854 men and women participants in the THUSA study (>15years) and 1262 women participants in the PURE study (>35years) were included in the analysis. The relationship between iron and anthropometric indicators of CVD risk was examined in the THUSA study while that of iron status, anthropometric and biological markers of CVD risk was examined in the PURE study. Results: In the THUSA study, ferritin was positively associated with body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), body fat and subscapular skinfold (r=0.141, 0.359, 0.396, 0.308, 0.141 respectively for men and 0.126, 0.232, 0.319, 0.126, 0.105 respectively for women; p<0.01). Only the women showed decreased serum iron concentration with increasing BMI (p<0.05). WC and WHR increased with increasing serum ferritin concentration for both genders (p<0.05). As for the PURE study, associations between iron status parameters and CVD risk factors were generally weak (r<0.3, p<0.01) and were not retained after adjusting for valid confounders. WC and WHR increased with increasing ferritin concentration (p<0.05). Conclusion: Although these results do not indicate any significant association between iron indices and biological markers of CVD, its association with anthropometric indices gives an indication of the possible contribution of iron in the aetiology of CVDs. Thus, it may be necessary to exercise caution on the emphasis placed on iron as a nutrient and iron intervention programmes because of the suggestive role of iron in CVD development.