Associations of Serum Ferritin and Transferrin % Saturation With All-cause, Cancer, and Cardiovascular Disease Mortality: Third National Health and Nutrition Examination Survey Follow-up Study

OBJECTIVES Even though experimental studies have suggested that iron can be involved in generating oxidative stress, epidemiologic studies on the association of markers of body iron stores with cardiovascular disease or cancer remain controversial. This study was performed to examine the association of serum ferritin and transferrin saturation (%TS) with all-cause, cancer, and cardiovascular mortality. METHODS The study subjects were men aged 50 years or older and postmenopausal women of the Third National Health and Nutrition Examination Survey 1988-1994. Participants were followed-up for mortality through December 31, 2006. RESULTS Serum ferritin was not associated with all-cause, cancer, or cardiovascular mortality for either men or postmenopausal women. However, all-cause, cancer, and cardiovascular mortality were inversely associated with %TS in men. Compared with men in the lowest quintile, adjusted hazard ratios for all-cause, cancer, and cardiovascular mortality were 0.85, 0.86, 0.76, and 0.74 (p for trend < 0.01), 0.82, 0.73, 0.75, and 0.63 (p for trend < 0.01), and 0.86, 0.81, 0.72, and 0.76 (p for trend < 0.01), respectively. For postmenopausal women, inverse associations were also observed for all-cause and cardiovascular mortality, but cancer mortality showed the significantly lower mortality only in the 2nd quintile of %TS compared with that of the 1st quintile. CONCLUSIONS Unlike speculation on the role of iron from experimental studies, %TS was inversely associated with all-cause, cancer and cardiovascular mortality in men and postmenopausal women. On the other hand, serum ferritin was not associated with all-cause, cancer, or cardiovascular mortality.