New research suggests iron deficiencies could raise stroke risk by making blood "sticky." 

Ischaemic strokes usually occur when blood supply to the brain is intercepted by clots, an Imperial College London news release reported. 

Past studies have suggested that iron deficiencies (which affect about two billion people worldwide) increase stroke risk, but medical experts were not sure how the two were related. 

The researchers found iron deficiencies can increase the stickiness of platelets, which are small blood cells. A link between iron deficiencies and the stickiness of platelets was discovered 40 years ago, but the connection of these findings to stroke risk has been overlooked until now.

The research team looked at 497 patients who had a rare condition called hereditary haemorrhagic telangiectasia (HHT) which causes enlarged blood vessels in the lungs. These blood vessels usually work to filter out small clots before the blood enters the arteries, but when these vessels are enlarged they are more likely to allow a clot to pass through to the brain. 

The team found the patients who were iron deficient were more likely to suffer a stroke. 

"Since platelets in the blood stick together more if you are short of iron, we think this may explain why being short of iron can lead to strokes, though much more research will be needed to prove this link," Doctor Claire Shovlin, from the National Heart and Lung Institute at Imperial College London, said in the news release. "The next step is to test whether we can reduce high-risk patients' chances of having a stroke by treating their iron deficiency. We will be able to look at whether their platelets become less sticky. There are many additional steps from a clot blocking a blood vessel to the final stroke developing, so it is still unclear just how important sticky platelets are to the overall process. We would certainly encourage more studies to investigate this link."