Aimee C. Richardson, Anne-Louise M. Heath, Jillian J. Haszard, Maria A. Polak, Lisa A. Houghton, Tamlin S. Conner

Studies investigating possible associations between iron status and mood or depressive symptoms have reported inconsistent results. However, they have neither used body iron to measure iron status nor measured mood using daily measures. We investigated whether body iron was associated with depressive symptoms, daily mood, daily tiredness, difficulty concentrating, and stress in young adult women and men. Young adult (17-25 years) women (n = 562) and men (n = 323) completed the Center for Epidemiologic Studies Depression Scale, then reported negative and positive mood, and other states daily for 13 days. Non-fasting venous blood was collected to determine hemoglobin, serum ferritin and soluble transferrin receptor (to calculate body iron), C-reactive protein, and alpha-1-acid glycoprotein concentration. Regression models tested linear associations between body iron and the outcome variables, controlling for possible confounders. No associations were found between body iron and the outcome variables in women. However, higher body iron was associated with more depressive symptoms in men (3.4% more per body iron mg/kg; 95% confidence intervals (CI): 0.8%, 5.9%). In young adult women, body iron is unlikely to be associated with significant deficits in mood or depressive symptoms. However, higher body iron may be associated with more depressive symptoms in young adult men.