J.D. Moyer

sci-fi writer, beat maker, self-experimenter

To Protect Your Heart, You Need to Bleed


Photo courtesy of Gordonator.com via Creative Commons license

This post is about why you should let someone stick a needle in your arm, take your blood, and sell it (in exchange for a cup of juice and some cookies).

If you’re over thirty and male, or a post-menopausal woman, you should probably be donating blood every 2-4 months. If you’re not eligible to give blood (due to a recent tattoo, international travel, illness, needle use, medication, or being a gay man) then you should take steps to reduce your iron intake and absorption.

Why? Reducing iron stores in the body (though blood donation or reducing iron intake) is probably one of the easiest things you can do to sharply reduce your chance of heart attack, cancer, and Type 2 diabetes. Those three categories of disease account for over 50% of deaths in the U.S. (link to PDF, see page 5 for chart).

People prone to anemia probably shouldn’t give blood, but it’s worth noting that anemia can also be caused by B12 or copper deficiency. Usually doctors just prescribe iron supplements when anemia is diagnosed, which can result in iron overload if the cause of anemia isn’t iron deficiency.

If you’re a premenopausal non-smoking non-diabetic woman, you have a much reduced risk of heart disease, probably due to lower iron levels (though estrogen levels may also be a factor). But after women stop menstruating, heart disease becomes the leading health risk (women are especially prone to vascular dysfunction; blood flow decreases even when the major arteries are clear).

Donating blood on a regular basis (and thus reducing the amount of stored iron in your body) improves your health in three ways:

1) Reduces chance of heart attack, reduces hardening of the arteries

High serum iron levels immediately constrict blood vessels, reduce blood flow, and in the long term lead to hardening of the arteries. “Iron loading impairs endothelial function, mostly due to oxidative stress,” says Hidehiro Matsuoka, MD, PhD (lead researcher and chief of the Kurume University School of Medicine’s hypertension program).

Donating blood, even as infrequently as once or twice a year, reduces iron levels in the body (by as much as 250mg per donation), and markedly reduces the chance of heart attack.

 2) Reducing iron stores improves insulin sensitivity, thus reducing the chance of Type 2 diabetes

This post from Stephen Guyenet discusses the relationship between iron and insulin sensitivity in some detail.

This study looked at insulin resistance in Type 2 non-alcoholic fatty liver disease, and found that iron reduction via phlebotomies (removing blood from the body) significantly improved insulin sensitivity.

This article from the American Diabetes Association discusses the glucose-iron relationship in depth, and reaches a similar conclusion. From the article:

Phlebotomy was followed by decreases in serum glucose, cholesterol, triglycerides and apoprotein B (14), and by improvement in both β-cell secretion and peripheral insulin action in patients with type 2 diabetes (15). A significant impact of tissue iron excess on systemic effects of diabetes is suggested by recent reports in which iron appears to influence the development of diabetic nephropathy and vascular dysfunction.

Excess iron is a killer — get rid of it!

3) Reducing iron stores decreases cancer risk

This study followed up, years later, with patients who had undergone iron reduction therapy in order to improve vascular health, and found that the iron reduction group had significantly lower cancer risk and mortality.

This older but quite large study found an inverse relationship between iron levels and cancer risk, especially in men.

This study found that high iron stores are associated with a higher risk of death from cancer in postmenopausal women.


I recently learned through 23andMe that I am heterozygous for the gene that causes hemochromatosis. If I had both copies of the mutated gene, I would have a very high chance of absorbing and retaining too much iron, resulting in serious health problems. According to this study, heterozygous carriers of this gene also tend to accumulate iron in the body as they age at a faster rate than the normal population (especially when the gene is inherited from the father). I inherited this particular gene from my mother (she also did the 23andMe test, so we can compare), but I am cautious with iron intake nonetheless.

Modulating Iron Levels Via Diet

Iron is an essential nutrient, and many people don’t get enough. If you are a growing child, a menstruating woman, or have digestive issues that reduce iron absorption, you might need to boost your iron levels in order to feel energetic. You can do this by:

  • eating iron-rich animal foods like beef, chicken liver, oysters, clams, and mussels (all very good sources of heme iron which is easily absorbed and utilized)
  • eat iron-rich plant foods like beans, tofu, and pumpkin seeds (all good sources of non-heme iron)
  • eat iron-rich foods with vitamin-C rich foods, or a vitamin C supplement, which increases iron absorption (taking vitamin C with each meal can triple total iron absorption)
  • taking iron supplements (non-heme iron), which most includes multivitamin-mineral supplements and many breakfast cereals
  • cooking with cast iron, especially if the recipe includes an acidic ingredient (like tomato sauce, wine, or lemon juice)
  • consume beverages high in tannins (like coffee and tea) in between meals instead of with meals; tannins reduce iron absorption
  • don’t consume calcium supplements or calcium-rich foods (like dairy products) with iron-rich foods; calcium also reduces iron absorption
  • don’t consume foods rich in phytates (most grains and legumes, especially oats) with iron-rich foods

If you want to reduce iron absorption, follow the opposite advice. Avoiding iron supplementation is especially important. I wouldn’t recommend drinking coffee and tea with every meal, or trying to eat a lot of phytate-rich foods, as you could end up reducing absorption of other nutrients that you do need.

Heart Health Summary

I’ve written before about how to prevent heart disease, highlighting the importance of sunlight and not smoking.

But what’s most important, in terms of lifestyle changes? The idea that saturated fat and cholesterol intake lead to heart disease has been largely discredited, but that doesn’t mean diet isn’t important.

Genetics may protect some individuals against specific risks factors (everyone knows someone with a grandmother who smoked like a chimney and live to be 100). But it may be possible to group lifestyle factors into “very important” and “somewhat important” (in terms of protecting against heart disease). Here’s my attempt:

Very Important Lifestyle Factors to Reduce Risk of Heart Disease

  • don’t smoke, avoid extreme air pollution
  • prevent iron overload (oxidation) and sodium overload (high blood pressure)
  • get regular sunshine (convert nitrates in skin to nitric oxide)
  • avoid too much sitting, move around every day
  • control weight (especially abdominal and visceral fat) by limiting total carbohydrate (especially refined and high glycemic foods)

Somewhat Important Lifestyle Factors to Reduce Risk of Heart Disease

  • exercise vigorously several times a week
  • reduce chronic stress (acute/brief stress is not harmful)
  • eat well (low processed/refined foods, high nutrient, fresh food)
  • take helpful supplements (vitamin K2, magnesium, fish oil, coenzyme Q10)

I could be wrong, but that’s my best guess. A multi-vitamin and jogging a few times a week isn’t going to protect your heart if you’re overweight, you sit a lot, you smoke, and you don’t get sunlight on your skin on a regular basis.

On the other hand, simple lifestyle changes like getting more sun exposure, converting to a standing desk, giving blood regularly, or losing a spare tire might mitigate other risk factors. If you do all of those things, you’re probably in good shape even if you don’t exercise vigorously and eat perfectly.

Another benefit of giving blood is that it feels pretty good. You’re probably saving a life every time you donate! And it’s weird, but kind of amazing, to think of your blood circulating in another person’s body. We are all connected, but the blood donor and receiver more than others.

Good health to you — may you live long and prosper!





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  1. Hi J.D.

    Firstly, thanks for writing this blog. I think it’s approximately 2 years since I added this to my RSS reader, and I’ve enjoyed many of your articles. Article I especially remember is the one about prayer (as an atheist).

    Secondly, I have been reading health blogs for several years now, and I’ve also started writing some own articles. I think you might like some of them:

  2. Want another good reason to check/monitor your iron levels? For those who have not been to 23andMe and may not be aware of their status – the American College of Clinical Pathologists recommends that EVERYONE be tested for hemochromatosis (HC) by age 25. This hereditary condition is present in about 10-15% of the population of the U.S. – much more common than most people think. Consequences of iron accumulation: liver cirrhosis, liver cancer, heart attack, kidney failure. Have your doctor test your ferritin (the protein that binds iron and keeps it in the body), iron saturation percent, and TIBC (total iron blood count). If anything is amiss in those numbers, you should check for the gene mutation for HC. If anyone in your family tests positive for the gene mutation, everyone should be tested. This condition is easily controlled through phlebotomy. Average statistics are that if both parents are carriers of the gene mutation and if they have four children, one will be actively affected (need lifelong blood draws), two will be carriers and one will not carry at all. If you’re married or going to be married and are planning on having children, you should both be aware of your status. These tests are not expensive and can save lives.

    • Thanks for sharing that — I wasn’t aware of the different varieties of iron-related blood tests. When you donate blood they only test your hemoglobin/hematocrit (low hemoglobin might indicate iron deficiency, but could also be related to other health issues).

  3. Sometimes copper deficiencies can be due to high levels of zinc as zinc blocks copper absorption.

  4. C

    Interesting concept! Many should also consider if they are healthy enough for donation. I worry of those with chronic infections (herpes family, mycoplasma, etc) contributing to blood stores. I do love that 23andMe makes it so easy to obtain this type of valuable information however. Its easy and affordable. I’m particularly interested in looking at methylation snps. http://bit.ly/RsOo8o

  5. Mags

    There’s zero evidence that losing a spare tire actually has any kind of causative effect on long term mortality rates. There are actually not enough people who have lost weight and kept it off for 5+ or even 2+ years to even do a study on. I would suggest reading Health at Every Size asap

    There *is* evidence that a “spare tire” as you put it correlates with a longer lifespan:

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