Studies have repeatedly demonstrated that blood donors experience lower mortality than the general population, but some have suggested that this may be due to healthier people donating blood.

A 2015 analysis of the Scandinavian Donation and Transfusion database (SCANDAT) found that after adjusting for the internal healthy donor effect, each additional annual donation of blood was associated with a 7.5% decreased risk of death over some number of years.

(I’m waiting for a copy of the study to find out the average number of years of follow-up.)

In other words, the more frequent someone donated blood, the lower their risk of death.

The analyses included 1,182,495 donors of whom 15,401 died during 9,526,627 person-years of follow-up.

Men who donated blood were 88% less likely to have a heart attack during a 9-year followup compared to men who did not donate blood according to a 1998 study from Finland.

This was after adjusting for age and coronary disease risk factors.

Only one (1) man out of 153 (0.7%) who had donated blood in the previous 24 months before baseline had a heart attack during 1984 to 1995, whereas 316 men of 2529 (12.5%) who had not donated blood had a heart attack.

“These findings suggest that frequent blood loss through voluntary blood donations may be associated with a reduced risk of acute myocardial infarction in middle-aged men,” the authors of the study concluded.