Blood stored for transfusions starts to go bad within hours after it's removed from the body and can hurt more than help many people who receive it, reports Time magazine. Doctors have long known that transfusions put many patients at higher risk for heart attacks and death, and now a new study has identified the culprit as depleted levels of nitric oxide in banked blood.
Nitric Oxide helps red blood cells deliver oxygen—and it's almost completely gone from banked blood by the 42-day expiration deadline, according to the study in Proceedings of the National Academy of Sciences. "We are giving blood that cannot deliver oxygen properly," said the lead researcher. Scientists say the gas can be replaced, and that stored blood could even be "supercharged" with nitric oxide to further reduce heart attack risk.