Consuming iron-rich meats linked to greater risk for type 2 diabetes

Key takeaways:

• Individuals with the highest heme iron intake had a 26% greater risk for developing type 2 diabetes.
• Association observed for higher heme iron intake and increased biomarker values.

A higher intake of heme iron may be linked to an increased risk for developing type 2 diabetes, study results published in Nature Metabolism showed.

Researchers also reported an association between heme iron intake and higher levels of several biomarkers, according to an updated analysis of findings from a retrospective cohort study.

“This is the first time we’ve put all of the pieces together and come up with a pretty comprehensive picture of the relationship between heme iron, red meat and diabetes,” Frank B. Hu, MD, MPH, PhD, the Fredrick J. Stare Professor of Nutrition and Epidemiology at Harvard, told Healio.

According to background information from the American Red Cross, heme iron is found in food sources like meat, seafood and poultry, whereas non-heme iron can be found in vegetables, nuts and fruits.

In the study, Hu and colleagues evaluated 36 years’ worth of dietary data from 204,615 participants (79% women) from the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study.

They also assessed the plasma metabolic biomarkers of 37,544 participants and the metabolic profiles of 9,024 participants to better understand the biological mechanisms behind the association between diabetes and heme iron.

Overall, participants in the highest heme iron intake group had a 26% higher risk for developing type 2 diabetes compared with those in the lowest intake group (HR = 1.26; 95% CI, 1.2-1.33).

“We observed a stronger unfavorable association for heme iron intake among participants with a lower BMI compared with those with a higher BMI,” Hu and colleagues wrote.

They added that this finding could be due to obesity potentially affecting the body’s ability to store iron.

Study investigators reported no associations between diabetes and a greater intake of total iron, non-heme iron or supplemental iron.

Heme iron also accounted for a large proportion of the association between unprocessed red meat intake and risk for diabetes “as well as a modest to moderate proportion for several dietary patterns,” Hu and colleagues wrote.

Researchers also noted an association between higher heme iron intake and elevated levels of biomarkers like leptin, c-peptide, triglycerides, and C-reactive protein. They also identified several metabolites tying heme iron to diabetes risk, including uric acid.

Hu and colleagues noted some study limitations. For example, most participants were white health professionals, diminishing the general applicability of the results to other diverse populations.

Additionally, “we were unable to identify other prospective cohorts that have repeatedly measured heme iron intake along with similar metabolic and metabolomic biomarkers to replicate our findings,” the researchers noted.

“Iron is an essential nutrient, so it’s a double-edged sword,” Hu explained. “On the one hand, iron deficiency is not good because it causes anemia, but too much iron, especially heme iron, can be harmful because it increases the risk of inflammation and diabetes.”

He said that switching from meat-based diets, especially those centered around red meat, to plant-based diets “can substantially reduce heme iron intake and also reduce the risk for type 2 diabetes.”

Hu added that people who still want animal-based diets do not have to completely stay away from red meat, “but they can also replace it with poultry or fish and healthy plant-based proteins like nuts and legumes.”

References:

• Iron rich foods. Available at: https://www.redcrossblood.org/donate-blood/blood-donation-process/before-during-after/iron-blood-donation/iron-rich-foods.html. Accessed Aug. 19, 2024.
• Significant link found between heme iron, found in red meat and other animal products, and type 2 diabetes risk. Available at: https://www.hsph.harvard.edu/news/press-releases/significant-link-found-between-heme-iron-found-in-red-meat-and-other-animal-products-and-type-2-diabetes-risk/. Published Aug. 13, 2024. Accessed Aug. 19, 2024.
• Wang F, et al. Nat Metab. 2024;doi:10.1038/s42255-024-01109-5.