When you donate blood, you lower your body’s iron stores.
Iron is an essential nutrient, but in excess, it becomes a pro-oxidant, generating free radicals that damage DNA, proteins, and lipids.
This oxidative stress causes chronic inflammation and is a well-established contributor to cancer, especially in organs where iron accumulates: the liver, colon, and pancreas.
Once iron is absorbed into the bloodstream and stored in tissues, the body has no active way to eliminate the excess. There’s no iron “exit route” like there is for water (urine), carbon dioxide (breathing), or sodium (sweating).
The only ways humans lose iron are through:
- Blood loss (from menstruation, injury, or donation): While women lose iron through menstruation, their bodies absorb it more efficiently than men, helping to offset the loss.
- Shedding skin cells
- Loss of intestinal cells in feces
- Very small amounts in sweat
But these are passive and very slow. So if you’re absorbing too much iron (from food, supplements, or fortified products), it builds up over time in organs like the liver, pancreas, brain, and heart, where it can cause oxidative damage and inflammation.
We never developed a mechanism to excrete excess iron because we never needed one. Iron is essential for life: it carries oxygen to tissues through hemoglobin and supports energy production in every cell. But for most of human history, iron was relatively scarce in the diet, especially in its unbound, non-heme form.
We are now exposed to unnaturally high levels of iron. In the United States, iron fortification began in the 1940s as part of a broader effort to combat malnutrition. Enrichment policies made it mandatory to add synthetic iron to refined grains like flour, cereals, and bread.
Today, most people consume more iron than necessary, largely due to fortified foods, supplements, prenatal supplements, and multivitamins—many of which contain a cheap, highly reactive form of iron. The industrial, isolated form of iron is not well-regulated by the body, and when consumed in excess, it can lead to unabsorbed iron floating in the gut or free iron in circulation, which is dangerous.
Our biology is still wired to hold onto iron as a precious resource, but in the modern world, that same trait is contributing to rising rates of iron overload, oxidative stress, and chronic disease.
Health risks associated with excess iron:
- Increased risk of cancer, Alzheimer’s, autism, heart disease, liver disease, type 2 diabetes, and cancer.
- Iron is often marketed to women, as most anemia is automatically interpreted as an iron deficiency. But anemia simply means low red blood cell count or low hemoglobin, it does not automatically mean low iron. There are many potential causes of anemia, including hypothyroidism, vitamin B12 or folate deficiency, copper deficiency, chronic inflammation, and even liver dysfunction.
- When anemia is caused by a different nutrient deficiency (vitamin B12, folate, vitamin E, vitamin A, zinc, etc.), iron can actually worsen the problem by depleting other critical nutrients.
Elevated ferritin, an iron storage protein, is often observed in cancer patients and associated with worse outcomes: especially in breast, liver, and colorectal. Although ferritin can also rise in response to inflammation, persistently high levels may indicate underlying iron overload.
When you donate blood, you lose approximately 200–250 mg of iron with each donation, most of it in the form of hemoglobin, the iron-rich protein in red blood cells that carries oxygen throughout the body.
To rebuild the lost blood, your body must mobilize iron from internal storage, primarily from the liver, spleen, and bone marrow, to create new red blood cells. Over time, especially with regular donation, this process leads to a gradual depletion of excess iron stores, helping to maintain iron at healthier, more balanced levels.
Blood donation, or therapeutic phlebotomy, is a straightforward way to reduce excess iron. Each blood draw removes a portion of the body’s stored iron, which is then used to make new red blood cells. Over time, this can lower iron saturation and ferritin levels.
This reduction in iron load has measurable benefits: it lowers oxidative stress, reduces the risk of diseases associated with iron overload (like cancer, heart disease, and diabetes), and relieves the strain placed on organs like the liver, heart, and pancreas.
A 2022 study of over 3.3 million people in China found that blood donors had a 24% lower risk of malignant tumors and a 15% lower risk of benign tumors compared to non-donors.The authors suggest this protective effect may be due to lower iron levels.
How can we protect against excess iron and avoid iron overload?
- Avoid supplements and foods containing added iron (fortified grains, prenatal supplements, multivitamins, etc).
- Regularly consume coffee and dairy. (Both can protect against the excessive accumulation of iron)
- Opt for white sea salts which will be lower in iron.
- Avoid consuming naturally iron rich foods with sources of vitamin C. (This can enhance iron absorption.)
- Use mainly stainless steel and glass cookware.
- Include sources of vitamin E to protect against both the depleting effect of iron and its free radicals.
- Look for foods or supplements containing lactoferrin, which can help to regulate iron levels in the body.
- Donate blood if necessary.