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Comment by erispoe | Hacker News Reader

> Men get advised to donate blood to lower their risk of heart disease.

I had never heard of that and did not find any article supporting that from a quick search. I found observational studies concluding that men who donate blood are less at risk for heart attacks, but did not control for selection bias (men who choose to or can donate blood are healthier) or for causes associated with the blood donation (e.g. you might discover you have high blood pressure while donating and seek treatment afterwards).

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One mechanism is the accumulation of excess iron, which can only be removed through bloodletting (e.g., menstruation).

https://www.webmd.com/men/features/too-much-iron-in-your-blo...

When I was diagnosed with high blood pressure I asked my doctor if I could donate more blood to lower it and she laughed and said your veins are not rigid pipes so it's not that easy.

I hate when people laugh at good questions. It really fucking annoys me.

The only stupid question is the one that isn't asked. Laughing at people really puts a dent in that, sadly.

How heavy is 1KG of iron?

Asked because not asking is apparently stupid but the question isn't.

Heavy enough to hurt you if it falls on your head, light enough to easily carry for a while.

Your answer isn't in weight but I asked how heavy it is, I expect a weight as answer.

Also I just doped a 1KG block of iron on my head from 1mm distance and it didn't hurt me. Then I cold rolled the block of iron into a 4x4m sheet of metal and I was unable to carry it around for more than a few seconds. Your answer is not only useless its also demonstrably wrong.

Maybe just maybe the question is stupid.

Why do you ask? Oh, for purposes of helpful demonstration. Seems like a question that is stupid by letter but not by spirit.

I do concede that there are dumb questions, of course. Although typically I like to say, there are no dumb questions but there are dumb times to ask questions.

Not a fan of the Socratic method, I see. When I was a child my father would ask me and my siblings "Which is heavier, a pound of feathers or a pound of lead?"

It wasn't a stupid question, it was an enlightening question, and your "stupid" question would not have sparked further discussion if you'd not asked it.

Thanks for proving the quotation right.

cope harder

Depends how they laugh. You can laugh in a good natured way at what should be a logical step but weirdly isn’t because of a non-obvious component of a system. They are funny in a similar way to how a joke is- something about the sudden change in perspective but with an flaw in the logic. But you are right that you need to make it clear you aren’t laughing at them to avoid such confusion.

I see what you mean, but I probably would have laughed at that because it's a really clever solution, not out of scorn. I am guessing a doctor that has spent decade hearing about various blood pressure medications and treatment would have an instant of "That's funny, why can't we just empty them a bit?"

when doctors laugh at me (I ask a lot of questions like this) I typically show them the underlying scientific article that supports it, and ask them if they've read it.

They stop laughing after that.

It does seem like a reasonable question, so I’m curious why you got that answer. Any domain experts here?

Not exactly my field, but IIRC blood pressure is not a passive result of how much blood is present, but rather is regulated by the body through a series of control networks. Removing blood does not reduce blood pressure (the body recognizes the dip and will adjust, plus more blood is made again quickly) because the problem is not that there is too much blood, but rather that the pressure setpoint is wrong.

Things like atherosclerosis reduce the space available for blood and increase the pressure without the body realizing the setpoint needs to change, thus why pressure increases.

It's a completely reasonable question. Blood pressure is a function of many variables, including vascular resistance, compliance, heart function, and --yes-- blood volume. In fact, one of the treatments for blood pressure, though rarely a first line, is to use a diuretic to reduce fluid volume. As other posters have commented, the body will compensate this to some degree, and it is not a very lasting or well-controlled effect, so the doctor is correct that bloodletting is not the standard of care for hypertension. But a mental experiment on the extreme margins can help address the question intuitively as well: suppose you removed all the blood, or else suppose you 100x-ed the blood supply. Would pressure fall and rise respectively? Of course it would.

diuretic are super low risk; why wouldn't they be first?

Blood pressure is more of a function of resistance to flow than volume (ignoring things like trauma induced hypovolemic shock - aka bleeding out) - which can be from many causes, including vasodilation/constriction, plaque buildup, compartment syndrome, heart issues (bad rhythm, valve issues, etc.), shock, or regulatory dysfunctions indirectly impacting those areas.

Volume issues, especially difficulty processing waste/removing excess fluid (renal failure or disfunction), can pop up, but reducing volume as a solution is kind of like taking gas out of your gas tank because your throttle keeps getting stuck and you don't want to run anyone over.

Yeah, it can kinda help maybe (and if you're desperate you should do it), but it isn't really addressing the underlying issue. Sometimes you don't have time or the ability to address the underlying issue, but it shouldn't be the first thing to go to.

Not ridiculous that say excess iron or blood volume could be an issue or help if addressed - just not a high odds thing to be tackling usually.

High blood pressure is rarely due to excessive blood volume, but rather due to the constriction of small arteries.

The effect of blood donation on health is through the reduction of iron (which is a both necessary and toxic element), not blood volume.

Your blood volume is replenished in days, where as replenishing your iron stores takes longer.

The doctor laughed at that? Even if wrong that’s a pretty intuitive thing to think. It’s a very reasonable question - as would the inverse (adding more blood to raise pressure).

I doubt it was a "ha-ha you're a stupid idiot" laugh but more of the sort of laugh you'd do when a toddler does something that makes perfect common sense, but violates social norms (like discussing their bowel movements with strangers).

Quick and dirty search gets me a piece titled Health benefits of blood donation which says (in part):

Studies have shown that, in general, Americans tend to consume more iron on a daily basis than is necessary for good health. Ingestion of quantities of iron beyond a certain quantity can promote formation of free radicals in the body. Free radicals have justly earned their reputation for causing cellular changes which can disrupt normal cell function and increase the risk of certain chronic diseases such as heart disease and cancer. This is more likely to be a problem for men and post menopausal women...

https://medicalwesthospital.org/january-is-blood-donor-month...

I'm American. If you aren't, that might be a factor.

The paragraph you quoted references (but does not cite) studies about the effect of excessive iron consumption, not evidence for a causal link from blood donation to reduced cardiovascular risks.

It seems that there is some correlation between cardiovascular risk and blood donation, but this might just be due to a confounding factor: healthy people tend to donate blood more.

E.g. this study [1]:

Despite the significant difference in QRISK2 parameters between study groups, none of these parameters was correlated to the extent of donation when controlling for age, BMI and smoking status.

Or this one [2]:

No significant associations were found between blood donation and the risk of myocardial infarction in analyses restricted to men with hypercholesterolemia or those who never used antioxidant supplements or aspirin. The study results do not support the hypothesis that reduced body iron stores lower CHD risk.

Ironically this other Dutch study [3], shows an association (not causal) between frequent blood donation and cardiovascular health in women but not in men.

[1]: https://pubmed.ncbi.nlm.nih.gov/28797569/ [2]: https://www.ahajournals.org/doi/full/10.1161/01.cir.103.1.52 [3]: https://heart.bmj.com/content/105/16/1260

My recollection is that the inference that men should donate blood to protect their heart health is based at least in part on the fact that women see an increase in heart disease around the time they stop menstruating:

Once women reach the age of 50, about the age of natural menopause, their risk for heart disease increases dramatically.

https://www.webmd.com/menopause/guide/menopause-heart-diseas...

How different is the increase of heart disease risk for men above 50?

A quick search indicates men actually see an increase after age 45. Some additional stats from the below source:

The average lifetime risk of developing cardiovascular disease was around 52% for men and 39% for women.

Lifetime risk jumped to 69% for men and 50% for women who had two or more cardiovascular risk factors by age 50.

Lifetime risk was just 5% among men and 8% among women who had optimal risk factors for cardiovascular disease at age 50.

https://www.webmd.com/heart-disease/news/20060206/how-great-...

> Once women reach the age of 50, about the age of natural menopause, their risk for heart disease increases dramatically.

Wouldn't the hormonal changes associated with menopause be a more likely explanation for the increase in heart disease risk than the fact they are no longer losing blood periodically?

The correct answer is probably "both" rather than only one or the other. It's humans that like to create simple explanations and clear cut categories, not nature. Nature gives us egg-laying mammals because nature didn't ask our opinion beforehand.

Any thoughts on what Americans consume more of that gives them more iron?

Aside from the obvious (meat, nuts), fortification of processed foods is more common in the US than other countires, and the FDA has some mandatory fortification rules. Breakfast cereals and flour are required to be fortified with iron, amongst other things.

My wife is a phlebotomist. She often sees men who've been prescribed blood donation to control their iron levels. Unfortunately that blood has to be discarded because of the high iron level.

> I had never heard of that and did not find any article supporting that from a quick search

It would be ironic if medieval doctors who "bled" patients to cure them had actually been on to something all this time.

Known to be effective in haemochromatosis, but thankfully now replaced with a medication.

Thanks for searching, I hope parent would be able to provide further details on that statement.

I got O -ve so I maintained >45 Kgs weight(min required) so I could donate when needed but my bones couldn't take it (Osteoporosis, Achondroplasia) and so now I've reduced my weight to 40 Kgs; It was bummer to hear donating lowers risk of heart disease although I wish it was true as its a win-win for donating blood.

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