Newsletter #207 - 3 Major Benefits of Blood Donation 🩸
Hey guys! So, this week, I thought I’d take a look at some of the little-known physiological benefits associated with blood donation.
Blood donation is obviously a prosocial and all-around nice thing to do, especially nowadays since the pandemic has reduced the number of donors. But remarkably, it also seems to be health-promoting, possibly because it reduces extra iron in the body. Each donation of 500mL of whole blood removes up to 250 mg of heme iron. That is obviously not so good if you have low hemoglobin, but could be profoundly helpful if you are among the millions who suffer from varying levels of iron overload. A study that came out just a couple weeks ago revealed that blood donation can remove persistent environmental contaminants that bind to proteins in blood, which could also explain some of the long-term improvements we see in blood donors.
PS: Before we get too carried away, it is worth noting that some of the benefits of blood donation in observational research may be partly due to a form of selection bias known as the “healthy donor effect.” Basically, people who donate blood tend to start out healthier, due to donor selection procedures and because sick folks just aren’t as likely to head out to the Red Cross. So these findings do kind of have to be taken with a grain of salt, even though there are plausible underlying biological mechanisms.
This Week's Research Highlights
Researchers in Australia recruited firefighters with elevated serum levels of perfluoroalkyl and polyfluoroalkyl substances (PFASs). These are synthetic compounds occurring in lots of industrial and consumer products because of their resistance to fire and water, and which have been linked to an array of adverse health effects. The firefighters were randomly split into three groups: 95 were assigned to just be observed (controls), 95 were assigned to donate plasma every 6 weeks, and 95 were assigned to donate blood every 12 weeks. After 12 months, the firefighters who donated blood or plasma showed a significant reduction in PFASs. Donating plasma was most effective, resulting in a ~30% reduction in the body burden of PFASs after 12 months. This may be because plasma can be donated more frequently, and because serum PFAS levels are two times higher than blood PFAS levels.
It has been suggested that one of the reasons for the disparity in cardiovascular risk between men and premenopausal women is due to frequent iron loss through menstruation, and that removal of excessive iron could reduce the risk of coronary events. To explore this hypothesis, researchers in eastern Finland followed a cohort of almost 3000 middle-aged men for almost nine years. After adjusting for predictive coronary disease risk factors, men who donated blood were found to have an 88% reduced risk of having a heart attack over the study period, compared to non-donors.
Researchers in Germany recruited 292 participants through blood transfusion services. Blood pressure was measured before and after blood donation, with each participant donating 1-4 times over a one year period. About half of them had elevated blood pressure at baseline. In these hypertensive subjects, four blood donations caused systolic and diastolic blood pressure to decrease from a mean of 155.9 ± 13.0 down to 143.7 ± 15.0 mmHg, and from 91.4 ± 9.2 down to 84.5 ± 9.3 mmHg, respectively. Donors with the most severe hypertension were shown to benefit the most, experiencing a 17.1 mm Hg drop in systolic BP and an 11.7 mmHg drop in diastolic BP. Previous research has shown that higher ferritin is linked to greater risk of hypertension, although markers of iron metabolism were not associated with changes in blood pressure in this study. (Also, hat tip to @kevinbass for sharing this paper on twitter).
Random Trivia & Weird News
Jim Becker, a lifelong fan of the Green Bay Packers, spent years donating blood in order to afford tickets, starting back in the mid-1950s.
It wasn’t until decades later that he was diagnosed with hemochromatosis, and doctors informed him that his frequent blood donation had likely kept him from an early grave. "They said if I hadn't done that, that most likely I would have been dead by 45," said Becker.
Podcasts We Loved This Week
- Shruti Naik: Why is inflammation a dangerous necessity? Via The Joy of Why.
- Heather Turgeon & Julie Wright: Why are teens so sleep deprived? Via Science Friday.
Products We Are Enjoying
Mason jar salads are a pretty popular form of meal prep, you’ve probably seen them a few times if you’ve ever scrolled through Instagram. But most glass mason jars aren’t really built with this purpose in mind - except for this one.
This is a 34 oz jar, so plenty of room for all of your salad ingredients, and there is a stainless steel cup embedded in the lid so you can pack dressing or sauce. Has a nice, old-timey aesthetic, and is very practical if you’re trying to up your meal prep game.
humanOS Catalog Feature of the Week
This week, we’d like to highlight our how-to guide for chrononutrition. We often fixate on what we are eating, when we are discussing diet and lifestyle, but we are gradually appreciating that when we eat also has a significant impact on our health and our daily performance.
This guide will help show you how to optimize your food timing, in alignment with the latest scientific research, to maintain robust circadian alignment and to ensure you are performing at your very best.
(PS: If you’re looking for a deeper dive into the subject of nutrient timing and other aspects of circadian physiology, please refer to our Circadian OS Program.)
Thanks for reading, and see y'all next week!