A new study from Harvard T.H. Chan School of Public Health has found a strong connection between high intake of heme iron, which is found in red meat and other animal products, and an increased risk of developing type 2 diabetes (T2D).
While previous studies have suggested a link between heme iron and T2D, this research provides a more comprehensive understanding of the relationship by incorporating multiple layers of data, including dietary reports, metabolic biomarkers, and advanced metabolomics.
Heme iron, the type of iron found in animal-based foods, differs from non-heme iron, which is primarily found in plant-based foods.
The study, published in Nature Metabolism, analyzed 36 years of dietary data from 206,615 adults participating in the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study.
The researchers assessed the participants’ intake of various forms of iron—including total iron, heme iron, non-heme iron, dietary iron, and supplemental iron—and examined the connection to their risk of developing T2D.
Lead author Fenglei Wang, a research associate in the Department of Nutrition at Harvard, explained that by combining epidemiological data with metabolic biomarkers and metabolomic profiles, the research team was able to gain a deeper understanding of how heme iron intake contributes to T2D risk and the metabolic pathways involved.
The study’s findings are significant. Participants who consumed the highest amounts of heme iron had a 26% higher risk of developing T2D compared to those who consumed the least.
The researchers also discovered that heme iron intake was responsible for more than half of the T2D risk associated with eating unprocessed red meat and contributed to the risk linked with several dietary patterns related to T2D.
In contrast, the study found no significant link between non-heme iron intake from diet or supplements and T2D risk.
In addition to analyzing dietary data, the researchers also examined biological mechanisms that might explain the connection between heme iron and T2D.
They looked at plasma metabolic biomarkers in a subset of 37,544 participants, focusing on indicators related to insulin levels, blood sugar, blood lipids, inflammation, and iron metabolism.
The results showed that higher heme iron intake was associated with adverse changes in these biomarkers, including increased levels of C-peptide, triglycerides, C-reactive protein, leptin, and markers of iron overload.
On the other hand, beneficial biomarkers like HDL cholesterol and adiponectin were lower in those with higher heme iron intake.
Further analysis identified a dozen blood metabolites, including L-valine, L-lysine, uric acid, and several lipid metabolites, that may play a role in the relationship between heme iron intake and T2D risk.
These metabolites have previously been linked to T2D, suggesting that they could be key factors in how heme iron contributes to the disease.
The findings of this study have important implications for public health and dietary guidelines. The researchers expressed concern about the growing trend of adding heme iron to plant-based meat alternatives to enhance their flavor and appearance.
While these products are becoming increasingly popular, the potential health risks associated with their heme iron content need further investigation.
Frank Hu, the Fredrick J. Stare Professor of Nutrition and Epidemiology at Harvard and the study’s corresponding author, emphasized the importance of making healthy dietary choices to prevent diabetes.
He suggested that reducing heme iron intake, particularly from red meat, and shifting toward a more plant-based diet could be effective strategies for lowering the risk of T2D.
However, the researchers also acknowledged some limitations of the study, including the possibility of incomplete accounting for confounding factors and measurement errors in the dietary data.
Additionally, the study population was predominantly white, so the findings need to be replicated in more diverse racial and ethnic groups to confirm their generalizability.
This research highlights the need for continued investigation into the dietary factors that contribute to the risk of T2D, particularly the role of heme iron.
By understanding the underlying mechanisms and making informed dietary choices, it may be possible to reduce the incidence of T2D and improve overall public health.
If you care about diabetes, please read studies that pomace olive oil could help lower blood cholesterol, and honey could help control blood sugar.
For more information about diabetes, please see recent studies about Vitamin D that may reduce dangerous complications in diabetes and results showing plant-based protein foods may help reverse type 2 diabetes.
The research findings can be found in Nature Metabolism.
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