Obesity, Iron and Young Women: Studies Investigating the Nutritional Implications of Excess Adiposity on Iron Status in Young Women

Abstract

THESIS TITLE: Obesity, iron and young women: studies investigating the nutritional implications of excess adiposity on iron status in young women. Recent evidence suggests a link between obesity, inflammation and disrupted iron metabolism that is mediated by the hormone hepcidin. This is of particular concern in young (18-30y) women as risk of weight gain and iron inadequacy is already high. Research in this demographic is also scarce, with limited studies using novel iron markers [e.g. soluble transferrin receptor (sTfR) and hepcidin] suitable for obese or inflamed individuals. To address the lack of research in this group, four studies were conducted for this thesis: (1) a systematic review summarising evidence on adult obesity, inflammation and iron status; (2) a cross-sectional study examining iron deficiency and obesity-related iron and hepcidin disturbances in young overweight women; (3) a 12-month randomised intervention assessing weight loss and dietary protein/haem iron manipulation on iron status in young women; and (4) a secondary genetic study on the intervention outcomes investigating impact of the rs855791 genetic polymorphism on body iron responses to altered protein/haem iron intake. The systematic review showed obese adults, particularly those with a body mass index >35kg/m2, exhibited biochemical changes consistent with inflammation and lower iron status. Conversely, this was not found in the subsequent study of young overweight women where simple iron deficiency (hypoferritinemia), was the major iron-related issue. With haem iron intake often recommended for treating iron deficiency, a randomised trial comparing two weight loss diets with contrasting protein and haem iron content was conducted in these women. Results demonstrated higher protein/haem iron intake to be useful for those with greater iron needs, and weight loss per se may be beneficial for normalising mild obesity-related iron disturbances. An exploration of genetics in the final study also revealed a significant effect of the rs855791 polymorphism on iron status, although its impact was mild relative to protein/haem iron intake.