blood donors live longer

One of the pieces of evidence used in our discussions of the health effects of iron has been the better health of blood donors. For example, blood donors have better insulin sensitivity and a greatly reduced risk of heart attack. But why do blood donors live longer?

The question always arises, however, to what extent these effects aren’t confounded by the fact that blood donors are healthier than non-donors even before they donate a drop of blood. People are prevented from donating blood due to high blood pressure, heart disease, cancer, and so on.

A recent study tried to get around that problem: “Blood donation and blood donor mortality after adjustment for a healthy donor effect”.(1)

The way the researchers did this was by comparing current donors to people who had stopped donating blood due to advanced age. (See here.)

Here’s what they found:

Analyses adjusted only for demographic characteristics showed a 18.6% reduction in mortality per additional annual donation (95% confidence interval [CI], 16.8%-20.4%). After additional adjustment for the internal healthy donor effect, each additional annual donation was associated with a 7.5% decreased mortality risk (95% CI, 5.7%-9.4%).

So presumably someone who donated 6 times a year, the maximum allowable, would have a 45% decreased risk of dying in a given year. That’s a lot.

Unadjusted except for demographics (presumably age and sex), mortality risk went down 18% for each additional annual donation.

The correlation is very likely closer to serum ferritin level, a measure of iron status. Blood donors start and end up with varying ferritin levels. But they didn’t have that data. Probably they would find that a donor who consistently had a 50 ng/ml ferritin would be less likely to die than one who only dropped to 80.

A previous study, unadjusted for the healthy donor effect, found that donors had an 88% lower risk of heart attack.

In another study, patients randomized to phlebotomy had 40% lower risk of cancer – and that can’t be attributed to being a healthy donor. (See here for both.)

There’s a wealth of evidence that accumulation of iron is toxic and accelerates aging, and blood donation is the most effective way to lower iron levels.

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  1. BB says:

    Fantastic series of articles on blood iron. What is the best way to get or safely perform phlebotomy if blood donation is not possible or very inconvenient?

    • P. D. Mangan says:

      Well, there is the option of therapeutic phlebotomy, but this requires a doctor’s orders and I don’t know how many doctors would be willing to do it absent frank iron overload. But some alternative types might, for example, an “integrative medicine” doc.

  2. Philomathean says:

    According to the Red Cross individuals with high blood pressure can donate blood if the blood pressure is controlled. Moreover, individuals with heart disease can donate as well as long as a specific timeframe has elapsed in relation to a traumatic event, e.g., six months post heart attack.

  3. Null says:

    I was rereading Seth Roberts’ blog and he mentioned that Norway heart disease markedly dropped during WWII and then went back up after the war . There are many many factors, but could widespread blood donation have been the cause? I can’t find any information about blood donations in Norway during that time and I don’t speak Norwegian.

    • P. D. Mangan says:

      As far as I know, blood donation was not widespread at the time. In my city, the current blood bank was founded in 1949, after a woman died for lack of a transfusion. I could be mistaken; but Norway was early knocked out of the war so presumably had low casualties. My guess as to lower rates of heart disease in WW2 is overall less food.

  4. Greg says:

    Great series on iron! What are your thoughts on lactoferrin for iron chelation? Chris Kresser mentions it in a video found here:

    • P. D. Mangan says:

      Thanks, Greg. Lactoferrin (found in whey) would, I believe, chelate iron in the gut, but whether it does so inside the body seems doubtful. The reason is that proteins are normally broken down into their constituent amino acids in the gut, so lactoferrin probably wouldn’t survive that process.

  5. Tom says:

    P.D., I remember in an earlier column you mentioned that for blood donation to be effective, it had to be whole blood, and not just platelets, or something to that effect. Is there any way to check for this? At an annual church or school blood drive, for example, are they generally taking whole blood, and is there a way to tell? Beyond simply asking, that is.

    • P. D. Mangan says:

      Hi Tom, that’s correct, only a whole blood donation lowers iron, since it’s red blood cells that contain iron. Platelets or plasma donations don’t lower iron. At a church or school blood drive, they’ll be collecting whole blood. Plasma and platelet donations require the use of relatively sophisticated equipment found only at a blood bank.

  6. gregor says:

    Don’t all women effectively “donate blood” regularly via menstruation? It seems an implication of this is that some of the gender gap in mortality might be iron-related. And does having iron rich blood have any benefits to counter the decreased longevity? Strength for example?

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