(P11-061-23) Dietary Heme Iron Intake and the Risk of Type 2 Diabetes: An Analysis in the Context of Dietary Patterns

Objectives: Higher heme iron intake, mainly from animal-based meat, is associated with an increased risk of type 2 diabetes (T2D). However, few studies have evaluated the possible mediating role of heme iron underlying the associations between dietary patterns and T2D risk. We aimed to examine whether and to what extent previously reported associations of red meat intake and several dietary patterns with T2D risk could be attributable to heme iron intake.

Methods: We followed 162,262 women from the Nurses’ Health Study I (1984-2016) and II (1991-2017) and 42,352 men from the Health Professionals Follow-up Study (1986-2016), who were free of diabetes, cardiovascular disease, and cancer at baseline. Validated food-frequency questionnaires were used to collect and derive dietary iron intake, total red meat consumption, and six T2D-related dietary patterns: Alternate Healthy Eating Index (AHEI), Alternate Mediterranean Diet (AMED), Dietary Approaches to Stop Hypertension(DASH) diet, healthful Plant-based Diet Index (hPDI), prudent diet, and western diet. Cox proportional hazards models were used to assess the association between iron intake and T2D risk. We further conducted mediation analyses to estimate the proportion of associations between these dietary patterns and T2D risk that could be explained by heme iron intake.

Results: During the follow-up of 5,221,605 person-years, we documented 19,311 incident T2D cases. After multivariable adjustment, higher heme iron intake was associated with an increased T2D risk (HR comparing extreme quintiles = 1.22; 95% CI: 1.16-1.29; P for trend < 0.001). No significant associations were observed for nonheme iron and total iron. Heme iron intake could explain 20.7% (95% CI: 9.5-39.2%) of the positive association between total red meat consumption and T2D risk. The attributable proportion is 10.5% (95% CI: 8.0-13.8%) for the positive association of western diet, and 15.8% (95% CI: 11.8-20.9%), 15.7% (95% CI: 11.5-21.0%), 14.3% (95% CI: 10.8-18.7%), 7.0% (95% CI: 5.4-8.9%), and 6.7% (95% CI: 4.1-10.8%) for the inverse associations of AMED, DASH diet, AHEI, hPDI, and prudent diet, accordingly.

Conclusions: Heme iron intake partially mediated the harmful associations for red meat consumption and western diet and the beneficial associations for several healthy dietary patterns with T2D.

Funding Sources: National Institute of Health