Iron is an essential mineral that plays a role in multiple different functions in the body. Most notably it is part of the hemoglobin protein that carries oxygen from the lungs to all other cells. It is also is involved in energy production and is required for DNA synthesis. There is some scientific evidence that suggests excess iron levels are linked to an increase in the risk for the development of diabetes; however further scientific studies are needed to establish whether excess iron actually contributes to the cause of the disease.
Iron Regulation
Iron levels in the body are tightly controlled by multiple mechanisms because it participates in vital functions, but excess iron can cause oxidative stress and tissue injury. The liver is the main storage site for excess iron. When iron levels are sufficient to maintain function the liver releases a protein called hepcidin. Hepcidin blocks absorption of iron in the intestine and decreases the release of iron into the blood. Dysregulation of hepcidin synthesis and release contributes to states of iron overload and iron deficiency. A study and review of the literature in the May 2009 issue of "Diabetes, Obesity and Metabolism" notes that between 53 and 82 percent of patients that have a genetic disorder of iron overload, called hereditary hemochromatosis develop type 2 diabetes.
Diabetes Risk
The study in "Diabetes, Obesity and Metabolism" reports that a marker of iron levels is high in overweight or obese, insulin resistant individuals and correlated to an increased risk for developing type 2 diabetes. A second study in the February 2004 issue of "The Journal of the American Medical Association" found that higher levels of iron are also associated with an increased risk for developing type 2 diabetes in healthy women. This association was also observed in men in a study conducted in Finland. Currently, no studies have evaluated rather reducing iron levels in type 2 diabetics reverses any metabolic abnormalities associated with the disease. These studies are necessary to determine if iron excess contributes to the cause and symptoms of the disease and not just coincidentally correlated.
Mechanism
Although iron makes up part of enzymes that act as antioxidants, iron can also increase the generation or reactive oxygen species and increase oxidative stress. A review in a 1993 issue of the "British Medical Bulletin" describes several studies that provide evidence that increased oxidative stress contributes to the development of type 2 diabetes. Iron has also been found in other studies to decrease glucose uptake by muscle and compromise insulin production and release.
Type 1 Diabetes
The great majority of studies that have investigated the correlation between iron and diabetes have evaluated the link with type 2 diabetes; however a recent pilot study in the September 2010 issue of "Diabetology and Metabolic Syndrome" reports that increased dietary intake of iron in the first four months of infancy is linked to an increase in the future development of type 1 diabetes. Although not yet confirmed in other studies it is important that this correlation is further investigated because most baby formulas are fortified with iron in order to prevent anemia.
References
- PubMed: Biomarkers of Body Iron Stores and Risk of Developing Type 2 Diabetes
- "The Journal of the American Medical Association"; Body Iron Stores in Relation to Risk of Type 2 Diabetes in Apparently Healthy Women; R. Jiang et al.; February 2004
- "British Medical Bulletin"; Diabetes Mellitus and Free Radicals; S.P. Wolff; 1993
- "Diabetology and Metabolic Syndrome"; Dietary Iron Intake in the First 4 Months of Infancy and the Development of Type 1 Diabetes: A Pilot Study; Ambika Ashraf et al.; September 2010
