News - Teenage Iron Intake Impacts Brain In Later Life
Iron and the proteins that transport it are critically important for brain function. Since both a deficiency and an excess of iron can negatively impact brain function, the body’s regulation of iron transport to the brain is crucial for healthy brain development. This is evidenced in a new study published in the Proceedings of the National Academy of Sciences, which shows that intake of iron in our teenage years has a huge impact on healthy brain wiring in later life.
To assess brain volume and integrity, Professor Thompson’s team collected brain MRI scans on 615 healthy young-adult twins and siblings, who had an average age of 23. Of these subjects, 574 were also scanned with a type of MRI called a “diffusion scan”, which maps the brain’s myelin connections and their strength, or integrity. 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.
Eight to 12 years before the current imaging study, researchers measured the subjects’ blood transferrin levels. Transferrin is the name given to the iron carrying protein. They hoped to determine whether iron availability in the developmentally crucial period of adolescence impacted the organisation of the brain later in life. By averaging the subjects’ transferrin levels, which had been assessed repeatedly at 12, 14 and 16 years of age, the researchers estimated iron availability to the brain during adolescence.
The team discovered that subjects 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 analyses of the twins in the study also revealed that a common set of genes influences both transferrin levels and brain structure.
“We found that healthy brain wiring in adults depended on having good iron levels in your teenage years,” Thompson said. “This connection was a lot stronger than we expected, especially as we were looking at people who were young and healthy — none of them would be considered iron-deficient. We also found a connection with a gene that explains why this is so. The gene itself seems to affect brain wiring, which was a big surprise,” he said.
“You wouldn’t think the iron in our diet would affect the brain so much in our teen years. But it turns out that it matters very much. Because myelin speeds your brain’s communications, and iron is vital for making myelin, poor iron levels in childhood erode your brain reserves which you need later in life to protect against aging and Alzheimer’s.” “This is remarkable, as we were not studying iron deficient people, just around 600 normal healthy people. It underscores the need for a balanced diet in the teenage years, when your brain’s command centre is still actively maturing,” he added.
Jahanshad et al. Brain structure in healthy adults is related to serum transferrin and the H63D polymorphism in the HFE gene. Proc Natl Acad Sci USA.