Researchers at Wake Forest Baptist Medical Center have used an animal model to demonstrate that high amounts of dietary iron, equivalent to eating large quantities of red meat, suppress leptin – the hormone regulating appetite, energy expenditure and metabolism. Human beings cannot excrete iron; hence accumulating large quantities of the mineral will increase the likelihood that leptin levels will drop significantly, increasing appetite and the chances of over-eating.

Leptin And Iron– Discovering The Connection

Scientists used mice to evaluate the effects of increased quantities of iron on leptin concentrations. Male mice were fed high and low-normal iron diets, 2000 mg/kg and 35 mg/kg respectively, for two months. The amount of iron in their fat tissue was then recorded.

A 215 percent increase in the amount of iron was observed in the mice fed the high iron diet. Moreover, the amount of leptin in their blood was 42 percent lower as compared to the mice fed the low-normal iron diets. These results were verified using ferritin blood tests (measure the quantity of iron stored) from a large clinical study previously conducted with human participants.

Making Inferences

Senior author Don McClain, M.D., Ph.D., Director of the Center on Diabetes, Obesity and Metabolism at Wake Forest Baptist corroborated the results, saying that the food intake of mice with high levels of iron in their system also increased. In humans, large quantities of dietary iron, even in the high-normal range, have also been highlighted as a contributory factor for diabetes, Alzheimer’s and fatty liver disease.

“Hence, this is another reason not to eat too much red meat, since the iron in red meat is more readily absorbed than iron from plant sources”, said Dr McClain.

The researchers also demonstrated that fat tissue responded to iron availability in order to regulate leptin expression. The optimal iron tissue level is still not known, explained Dr McClain, who hopes to conduct large-scale clinical trials for determining whether lowering iron levels has any impact on weight and risk of diabetes.

“The better we understand how iron works in the body, the better chance we have of finding new pathways that may be targets for the prevention and treatment of diabetes and other diseases”.

The study appeared recently in the Journal of Clinical Investigation.