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Dietary iron intake and risk of coronary disease among men
A Ascherio1, W C Willett, E B Rimm
1Department of Epidemiology, Harvard School of Public Health, Boston, MA.
Insights
Dietary iron intake does not increase coronary heart disease risk in men. However, high heme iron intake, found in red meat, may elevate the risk of myocardial infarction and is linked to higher iron stores.
Area of Science:
- Cardiovascular Disease Epidemiology
- Nutritional Science
- Iron Metabolism
Background:
- Investigated the relationship between dietary iron intake and coronary disease incidence.
- Focused on a large cohort of men aged 40-75 without prior cardiovascular disease.
- Utilized a 4-year follow-up period with baseline food frequency questionnaires.
Purpose of the Study:
- To examine the association between total and heme iron intake and coronary heart disease (CHD) risk.
- To determine if heme iron intake is linked to increased iron stores (serum ferritin).
- To evaluate the hypothesis that dietary iron increases coronary risk in men.
Main Methods:
- Prospective cohort study of 44,933 men.
- Data collection via food frequency questionnaires at baseline.
- Statistical analysis adjusted for established cardiovascular risk factors, dietary fats, and cholesterol.
Main Results:
- No significant association found between total iron intake and overall coronary heart disease risk.
- Higher total iron intake (highest quintile) showed a non-significant trend towards lower risk of fatal or nonfatal myocardial infarction.
- Increased risk of fatal coronary disease or nonfatal myocardial infarction observed in the highest quintile of heme iron intake (RR 1.42).
- Heme iron intake, but not total iron, correlated positively with serum ferritin levels.
Conclusions:
- Dietary iron in general does not appear to increase coronary risk in men.
- Higher heme iron intake is associated with an increased risk of myocardial infarction.
- Heme iron intake is positively associated with iron stores, suggesting a potential mechanism for increased cardiovascular risk.
Background:
We prospectively studied iron intake in relation to the incidence of coronary disease in a 4-year follow-up of 44,933 men (with no previous history of cardiovascular disease) aged 40 to 75 years in 1986 who completed a food frequency questionnaire at baseline.
Methods And Results:
We documented 844 incident cases of coronary disease (249 nonfatal myocardial infarctions, 137 coronary disease fatalities, and 458 bypass operations or angioplasties). After adjustment for established risk factors, there was no significant association between total iron intake and risk of coronary heart disease. Men in the highest quintile of total intake (median, 37 mg/d) had a relative risk (RR) of fatal coronary disease or nonfatal myocardial infarction of 0.73 (95% confidence intervals [CI], 0.51, 1.06) compared with men in the lowest quintile of intake (median, 11 mg/d). Dietary intake of heme iron--mainly from red meat--also was not significantly associated with risk of coronary heart disease. However, incidence of fatal coronary disease or nonfatal myocardial infarction was higher among men in the top quintile of heme iron intake compared with men in the lowest quintile (RR, 1.42; 95% CI, 1.02, 1.98). This association remained after adjustment for dietary cholesterol and fats. Heme iron but not total iron intake was positively correlated with serum ferritin among 123 members of the cohort who participated in a validation study.
Conclusions:
These results do not support the hypothesis that dietary iron in general increases coronary risk in men; they are consistent, however, with an increased risk of myocardial infarction among men with higher intake of heme iron, which is itself positively associated with iron stores.