Search for nutritional confounding factors in the relationship between iron deficiency and brain function.

This paper on confounding factors in the relationship between iron deficiency and brain function is mainly limited to nutritional factors, primarily factors that can contribute to the development of iron deficiency and that may have an independent direct action on brain function. Three theoretically possible confounders were found in a systematic search for dietary factors: 1) low intake of ascorbic acid, 2) excess of phytates, and 3) increased absorption of lead. Ascorbic acid has a marked effect on the bioavailability of dietary iron and is also known to directly influence various metabolic processes in the brain. Phytates inhibit the absorption not only of iron but also of zinc. An iron deficiency may thus be accompanied by a zinc deficiency which may affect mental performance. A state of iron deficiency may increase the absorption of lead from the diet, which in turn may affect brain function.