Volume 34
An extraordinary thing happened when those at high risk for heart disease were randomized to give blood—and it had nothing to do with their heart.
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Back in the early 80s, a pathologist in Florida suggested that the reason premenopausal women are protected from heart disease is that they have lower stores of iron in their body. The thought was since oxidized “cholesterol is important in atherosclerosis, and oxidation is catalyzed by iron,” maybe the “lower iron stores of [menstruating] women reduce their risk” of coronary heart disease. This novel suggestion, that “the longevity enjoyed by women over men might relate to the monthly [blood] loss [was] remarkable.” But, is it true?
Well, the consumption of heme iron—the iron found in blood and muscle—is “associated with…increased risk” of heart disease. Each milligram a day was “associated with a 27% increase in risk.” But, heme iron is found mainly in meat. So, it’s possible some of the other “constituents…in meat such as saturated fat and cholesterol are responsible” for the apparent link between heme iron and heart disease. If only we could find a way to get men to menstruate. Then, we could finally put the theory to the test.
Well, what about blood donations? Why just lose a little every month, when you can donate a whole unit at a time? This study, in Nebraska, suggested that blood donors seemed to have reduced risk. Another study, in Boston, failed to show any connection.
To resolve this question once and for all, one would really have to put it to the test. Take people at high risk for heart disease, randomly bleed half of them, and then follow them all over time, and see who gets more heart attacks. Maybe, it could turn the old “bloodletting” of the past into “bleeding edge technology.” And, that was actually what was suggested in the original paper, as a way to test this idea. It took twenty years, but researchers finally did it. Why did it take so long? Well, there isn’t much money in bloodletting these days. The leech lobby just isn’t as powerful as it used to be.
What did they find? It didn’t work. The blood donors ended up having the same number of heart attacks as the non-donor group. But, something extraordinary happened. The cancer rates dropped. A 37% reduction in overall cancer incidence, and those who developed cancer had a significantly reduced risk of death. An editorial in the Journal of the National Cancer Institute responded with near disbelief; the “results almost seem to be too good to be true.” Strikingly, they started to see cancer reduction benefits within six months, after just giving blood once. Here’s cancer mortality as the study progressed. As you can see, the cancer death rates started to diverge within just six months. This is consistent with the spike in cancer rates we see within just six months of getting blood, getting a blood transfusion. Maybe, that influx of iron accelerated the growth of hidden tumors.
