Iron's link to diabetes has been in the news over the last few years.
In February, 2004, a study that appeared in the Journal of the American Medical Association found that high levels of iron in the body almost tripled women's risk for developing diabetes. Researchers had examined iron stores in over 32,000 women who took part in the Nurses' Health Study and followed them for 10 years.
Recently, a study which appears in this month's issue of Diabetes Care found that women with high intakes of heme iron - the kind found primarily in meat - had a 28% greater risk of developing diabetes than women whose meat intake was lower. Researchers examined dietary intake of over 85,000 women who took part in the Nurses' Health Study and followed them for 20 years.
One item to note - This recent study found no association between diabetes and iron intake from supplements, iron intake from non-heme sources (such as spinach and other greens, beans, and fortified cereals), or total iron intake from all sources. It could only document a link between diabetes and the intake of heme iron. (Heme iron is a constituent of hemoglobin and myoglobin molecules in animals. Only about 40% of the total iron supplied by meat is in the heme form.)
Although this study investigated iron's association with the risk for developing diabetes, it did not reveal a mechanism, nor did it discuss what effect intake of heme iron would have in those already dealing with the disease. However, in an interview with Reuters Health, one of its authors theorized:
"In excess, these molecules create a state of "oxidative stress" that damages body cells over time. Oxidative stress could theoretically set the stage for diabetes by reducing body cells' sensitivity to the hormone insulin, Rajpathak explained."
- More evidence ties iron intake to diabetes risk
For the 2004 JAMA study:
Body Iron Stores in Relation to Risk of Type 2 Diabetes in Apparently Healthy Women
For a news summary of the JAMA study:
Diabetes risk may be associated with elevated iron levels
For the June, 2006 Diabetes Care study:
Iron Intake and the Risk of Type 2 Diabetes in Women