Long-term dietary iron intake and risk of non-fatal cardiovascular diseases in the China Health and Nutrition Survey.

ABSTRACT

AIMS: We aimed to investigate the association of long-term dietary iron intake with the risk of non-fatal cardiovascular diseases (CVDs), myocardial infarction (MI), and stroke in Chinese populations with predominantly plant-based diets by sex. METHODS AND RESULTS: A total of 17 107 participants (8569 men and 8538 women) aged 18-80 years in the China Health and Nutrition Survey (CHNS) 1989-2015 were included. Dietary intake was assessed repeatedly by three consecutive 24-h dietary recalls. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During a median follow-up of 11.1 years, the adjusted HRs (95% CIs) for non-fatal CVDs risk across quintiles of total iron intake in men were 1.00, 0.65 (0.46-0.93), 0.54 (0.37-0.78), 0.66 (0.46-0.94), 0.69 (0.47-1.03), but no significant association in women. Similar associations were found for stroke risk, but not for MI risk. The dose-response curves for the association of total iron and non-heme iron intake with the risk of non-fatal CVDs and stroke followed a reverse J-shape only in men and similar reverse J-shaped association of heme iron intake with non-fatal CVDs and stroke risk in both men and women (P-non-linearity <0.05). CONCLUSION: Moderate dietary iron intake may protect against non-fatal CVDs and stroke, especially in Chinese men consuming plant-based diets. Both quantity and quality of dietary iron intake should be considered in the prevention of non-fatal CVDs due to differences in dietary patterns among diverse populations.

This prospective cohort study, using data from 8569 men and 8538 women who participated in the China Health and Nutrition Survey (CHNS) 1989­2015, suggests that moderate intake of dietary iron may protect against non-fatal cardiovascular diseases (CVDs) and stroke, especially in men consuming predominantly plant-based diets. Key findings In men, the association of dietary intake of total iron, heme iron, and non-heme iron with the risk of non-fatal CVDs and stroke followed a reverse J-shape, with the lowest risk at ∼26 mg/d of total iron intake, ∼2 mg/d of heme iron intake, and ∼24 mg/d of non-heme iron intake. In women, a J-shaped association between dietary heme iron intake and the risk of non-fatal CVDs and stroke were observed, with the lowest risk at ∼1.8 mg/d of heme iron intake; while higher dietary intakes of total iron and non-heme iron tended to be associated with a lower risk of non-fatal stroke.