Associations of dietary total, heme, non-heme iron intake with diabetes, CVD, and all-cause mortality in men and women with diabetes.

BACKGROUND

Iron metabolism disorders significantly increase the risk of diabetes and its related complications by inducing oxidative stress, inflammation, insulin resistance, and disturbances in glucose and lipid metabolism. However, whether dietary iron intake can influence progression of diabetes remains unclear. The present study aims to investigate the relationship between total iron, heme iron, and non-heme iron intake and diabetes, CVD, and all-cause mortality among men and women with diabetes in the U.S. population.

METHODS

A total of 4416 adults with diabetes(2415 men and 2001 women) from the NHANES 2003-2014 were enrolled. Dietary information was collected by 24-h dietary recall during two nonconsecutive days. Dietary total iron intake was measured based on the dietary survey. Dietary heme iron intake was calculated based on its proportion in dietary total iron intake from each food. non-heme iron is the difference between total iron and heme iron. Diabetes, CVD, and all-cause mortality status were identified as main outcomes. Cox models and RCS analysis were performed to estimate the hazard ratios and 95%CIs.

RESULTS

For men, the participants with a higher dietary heme iron intake were associated with higher risks of CVD (HR = 1.61,95%CI:1.03-2.51) and all-cause mortality (HR = 1.42,95%CI:1.10-1.83). For women, participants in the highest quartile of dietary total/heme/non-heme iron intake had a higher diabetes mortality risk ((HR = 2.33,95%CI:1.24-4.38; HR = 1.87,95%CI:1.00-3.49; HR = 2.28,95%CI:1.19-4.39), compared to those in the lowest quartile. Additionally, the dose-response curve for the relationship between dietary non-heme iron intake and CVD mortality followed a reverse J-shape in women with diabetes.

CONCLUSIONS

Higher dietary heme iron intake was associated with an increased CVD mortality risk in both men and women with diabetes. Additionally, higher dietary total, heme, and non-heme iron intake was linked to an increased risk of diabetes mortality among women with diabetes. Therefore, women with diabetes should pay more attention on the overconsumption of any type of dietary iron.