Higher iron levels linked with increased risk of cardioembolic stroke

People with higher iron levels may be at greater risk of a certain type of stroke, new research has found.

A team from Imperial College London analysed the genetic data of more than 48,000 people and said they were surprised to find higher iron levels were associated with an elevated risk of cardioembolic stroke.

These strokes are typically caused by blood clots travelling from the heart to the brain, blocking blood and oxygen supply.

They are often associated with the heart condition atrial fibrillation, which causes an irregular heart rate and affects around one million people in the UK.

The findings, published in the journal Stroke, follow previous research suggesting iron may protect against stroke and coronary artery disease.

But the team cautioned against anyone reducing their own iron intake as they said further research was needed.

Lead author Dr Dipender Gill from Imperial’s School of Public Health said: “This result was unexpected.

“It was previously thought higher iron levels might protect against stroke but this study investigates this further to find that iron may actually increase the risk of some types of stroke.

“Iron is a vital nutrient, essential for a number of biological processes in the body, including transporting oxygen.

“However, previous research has suggested that in some cases iron can actual trigger blood to form a clot. This now needs further investigation.”

Researchers investigated the link between iron and stroke using a statistical method called Mendelian Randomization.

Using genetic data from public databases, they searched through the data of more than 48,000 people to work out the impact of genetics on iron status.

They focused on three points in the genome where a single “letter” difference in the DNA – called a single nucleotide polymorphism (SNP) – can slightly increase or reduce a person’s iron status.

When they searched for these same SNPs in data sets, including more than 60,000 stroke patients, they found those with the SNPs for higher iron status had a higher risk of cardioembolic stroke.

“This is an early-stage finding and we would certainly not recommend that patients at risk of stroke reduce their iron intake, as it has many crucial roles in the body,” Dr Gill added.

“However, our research does suggest doctors and scientists should now work towards further studies that investigate iron levels on the risk of different types of stroke, and cardiovascular disease more generally.”

The team also used the statistical technique to investigate other factors that may affect stroke risk.

They found people who have a naturally high number of cells called platelets, which are crucial to blood clotting and help to prevent bleeding, may have a higher risk of ischaemic stroke, caused by clots blocking blood supply to the brain.

Other findings included people with lower levels of a substance that helps the blood to clot, called Factor XI, may have a lower risk of cardioembolic stroke.

Researchers are currently investigating new treatments that help reduce the risk of stroke by cutting levels of Factor XI, and these new findings confirm that these types of drugs may hold promise.

Dr Gill said: “All these findings highlight potential treatments or lifestyle interventions that may help reduce stroke risk and that they may offer avenues for further study.

“Stroke is the second leading cause of death worldwide and causes around 32,000 deaths every year in the UK.

“But the disease is complicated – we now know that there are many distinct types, each with different causes.

“As we help unravel this further, it will give us a better picture of how to protect patients from stroke.”