Source of dietary iron determines the effect on blood pressure.
Most people are familiar with the mineral iron, and its close relationship the health of red blood cells. Iron deficiency can create one of the most common types of anemia, while excessive amounts of iron can promote oxidative damage to the cardiovascular system.
Blood pressure is not often associated with dietary iron status, so it was interesting to see this study by Imperial College in London published in July 2008. It looked at the two types of dietary iron and compared their effect on blood pressure.
Dietary iron is classified as either heme iron, or non-heme iron. Heme iron consists of iron bound to a protein complex, this is the type of iron found in red meats and fish and is very well-absorbed. Non-heme iron is the type found in plant foods and more poorly absorbed.
What the researchers found was very interesting. Heme iron, red meat especially, was associated with higher blood pressure (the effects were mainly seen on systolic pressure). Non-heme iron was associated with lower blood pressure.
Whether the different effects are due to the different absorption characteristics or something else remains to be determined. But the study is highly suggestive that anyone trying to lower or normalize blood pressure would be well-advised to limit or eliminate consumption of red meat.