A new Danish study points towards the safety of donating blood by finding that regular donors live longer than those who give blood infrequently, Videnskab.dk reports. But the study can’t answer once and for all if donating blood is safe because it doesn’t compare donors and non-donors.

The aim of the study was to find out if there were serious health risks to donating blood over and above the short-term symptoms experienced by some donors, such as fainting and pain from incorrect needle-sticks. Researchers particularly wanted to know about the long-term consequences of iron deficiency following a blood donation.

Henrik Ullman of Copenhagen University, the author of the study, told Videnskab.dk that he was relieved by the results.

“My reaction to the results was first and foremost relief. Given that those who have donated a lot live longer than those who have donated a little, there is no evidence there is anything dangerous about donating blood,” he said.

Not conclusive
The study used data from millions of blood donors in Denmark and Sweden, and Ullman explained there was good reason for this.

“It is the world’s biggest data set in this area,” he said. “Scandinavia is the only place where you can write such an article because it is the only place that has this type of register.”

But Ullman conceded that the study didn’t prove conclusively the safety of donating blood.

“The study can be used to reassure blood donors and blood banks. It says that it is seemingly healthy and safe to donate,” he said.

“But we are still working with other underlying effects that can have an impact on health.”

The methodological problem of comparing donors and non-donors is that donors are screened for health problems in order to be eligible to donate, so they are typically healthier than the general population.