Healthy brain development in adults seems to depend on having good iron levels in teenage years, a new US study suggests.
In the study, blood levels of transferrin, a protein that transports iron throughout the body and brain, were measured in 615 healthy teenagers (1). By averaging the participants’ transferrin levels, which were assessed repeatedly – at 12, 14 and 16 years of age – the researchers estimated iron availability to the brain during adolescence. Eight to 12 years later magnetic resonance imaging brain scans of the adolescents with an average age of 23 were analyzed. Of these subjects, 574 were also scanned to map the brain’s myelin connections and their strength, or integrity. The study results showed that the transferrin levels were related to detectable differences in both the brain’’s macro-structure and micro-structure when the adolescents reached young adulthood. Participants who had elevated transferrin levels – a common sign of poor iron levels in a person’’s diet – had structural changes in brain regions that are vulnerable to neurodegeneration. Further analyzes of twins who took part in the study revealed that a common set of genes influences both transferrin levels and brain structure.
The researchers commented that dietary iron seems to affect the brain very much during the teenage years. Because myelin speeds up the ’brain’s communication and iron is vital for making myelin, poor iron levels in childhood may erode brain reserves that are needed later in life to protect against aging and Alzheimer’s disease. This would be remarkable, as the scientists were not studying iron deficient but normal healthy people. They pointed out that the results underscore the need for a balanced diet in the teenage years, when the ’brain’s command center is still actively maturing. The discovery of a common set of genes that influences both transferrin levels and brain structure may shed light on the neural mechanisms by which iron affects cognition, neurodevelopment, and neurodegeneration. Myelin is the fatty sheath that coats the ’brain’s nerve axons, allowing for efficient conduction of nerve impulses, and iron plays a key role in myelin production.
Iron and the proteins that transport it are critically important for brain function. Iron deficiency is the most common nutritional deficiencies worldwide, causing poor cognitive achievement in school-aged children. Yet later in life, iron overload is associated with damage to the brain, and abnormally high iron concentrations have been found in the brains of patients with Alzheimer’s, Parkinson’s and Huntington disease. Since both deficiency and excess of iron can negatively impact brain function, the body’s regulation of iron transport to the brain is crucial. When iron levels are low, the liver produces more transferrin for increased iron transport.