Dietary iron intake and blood donations in relation to risk of type 2 diabetes in men: a prospective cohort study.
BACKGROUND
Excessive iron stores may promote insulin resistance and lead to the development of type 2 diabetes. However, prospective data relating iron intake and blood donations (determinants of body iron stores) to diabetes incidence are limited.


OBJECTIVE
We examined iron intake and blood donations in relation to the incidence of type 2 diabetes.


METHODS
We followed men aged 40-75 y who participated in the Health Professionals' Follow-up Study; were free of diabetes, cardiovascular disease, and cancer in 1986; and provided dietary data (n = 38 394). Of those participants, 33 541 also provided a history of blood donation during the past 30 y in 1992.


RESULTS
During 12 y of follow-up, we ascertained 1168 new cases of type 2 diabetes. After adjustment for age, body mass index, and other diabetes risk factors, total iron intake was not associated with the risk of type 2 diabetes. Intakes of total heme iron [multivariate relative risk (RR) for extreme quintiles: 1.28; 95% CI: 1.02, 1.61; P for trend = 0.045] and of heme iron from red meat (RR: 1.63; 1.26, 2.10; P for trend < 0.001) were associated with an increased risk. However, heme-iron intake from sources other than red meat was not associated with diabetes risk (RR: 0.99; 0.81, 1.22). No significant associations were found between blood donation and the risk of type 2 diabetes.


CONCLUSIONS
Heme-iron intake from red meat sources is positively associated with the risk of type 2 diabetes. Total iron intake, heme-iron intake from non-red meat sources, and blood donations are not related to the risk of type 2 diabetes.
Jiang
Rui
R
Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA. rjiang@hsph.harvard.edu
Ma
Jing
J
Ascherio
Alberto
A
Stampfer
Meir J
MJ
Willett
Walter C
WC
Hu
Frank B
FB
D000328:Adult; D000368:Aged; D001782:Blood Donors; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology*; D006418:Heme / Q000009:adverse effects*; D006801:Humans; D019190:Iron Overload / Q000150:complications* / Q000209:etiology; D019266:Iron, Dietary / Q000008:administration & dosage*; D008297:Male; D008460:Meat; D008875:Middle Aged; D011446:Prospective Studies
D019266:Iron, Dietary; D006418:Heme