Iron
Vital for oxygen transport, but balance is key.
Iron is essential for hemoglobin production, oxygen transport, and cellular energy metabolism. Both deficiency and excess are harmful. Iron deficiency causes anemia and fatigue, while excess iron promotes oxidative damage and is linked to increased risk of heart disease, diabetes, and neurodegeneration. Maintaining optimal iron status is one of the most important mineral balancing acts for longevity.
How Iron affects aging
Iron's day job is oxygen and energy: it sits at the center of hemoglobin and myoglobin, and iron-sulfur clusters are essential working parts of the mitochondrial electron transport chain. When iron runs low, the deficit shows up system-wide before anemia ever appears — fatigue, reduced exercise capacity, impaired concentration, restless legs — because every mitochondrion is running short. For menstruating women, endurance athletes, and frequent blood donors, deficiency is common enough to actively rule out rather than push through.
The other edge is chemistry: unbound "labile" iron catalyzes the Fenton reaction, converting mild oxidants into hydroxyl radicals that shred lipids and DNA. When lipid peroxidation overwhelms a cell's defenses, the cell dies by ferroptosis — an iron-dependent form of regulated cell death now implicated in neurodegeneration, cardiac injury, and kidney damage. Because the body has no active excretion route for iron, tissue stores tend to ratchet upward with age, accumulating in exactly the organs aging damages most, including the brain.
The genetic evidence has sharpened the overload concern. A large genomic analysis of healthspan, lifespan, and longevity found the implicated genes enriched for haem metabolism, and Mendelian randomization within it pointed to genetically higher serum iron as causally reducing healthy lifespan. This does not make iron a villain — deficiency is unambiguously harmful — but it supports the U-shaped view behind the ferritin target of roughly 40–100 ng/mL: enough to fuel mitochondria, not enough to feed the chemistry of decline.
Dosage
RDA: 8mg for men and postmenopausal women, 18mg for premenopausal women
Optimal for longevity: Longevity researchers recommend maintaining ferritin levels between 40-100 ng/mL. Excess iron is as dangerous as deficiency.
Iron is the nutrient to test before touching: a ferritin blood test (interpreted alongside inflammation markers, since ferritin rises with CRP) tells you which side of the U-curve you are on. If you are low, ferrous bisglycinate is gentler on the gut than ferrous sulfate, vitamin C taken alongside boosts absorption, and coffee, tea, and calcium block it — separate them by a couple of hours. Alternate-day dosing is increasingly favored to work with the body's hepcidin rhythm.
If you are not deficient, do not supplement — most men and postmenopausal women should avoid iron-containing multivitamins entirely. The tolerable upper limit is 45mg daily, and iron pills are a leading cause of accidental poisoning in children, so store them out of reach. If ferritin runs high, blood donation lowers it reliably, and it is worth screening for hereditary hemochromatosis, one of the most common genetic conditions in people of northern European ancestry.
Deficiency signs
~10% of US women of childbearing age are iron deficient; ~2% of men
- Fatigue and weakness
- Pale skin and brittle nails
- Cold hands and feet
- Shortness of breath during exercise
- Restless legs
Top food sources
What the research shows
This trial randomized 1,277 patients with peripheral arterial disease to iron reduction via scheduled blood draws or usual care. Despite the compelling theory, lowering iron stores did not significantly reduce all-cause mortality (20% versus 23%, p=0.17) or the combined endpoint of death, heart attack, and stroke. A null worth respecting: crude iron removal in people with established disease is not a proven longevity intervention, even if keeping stores moderate for life may still matter.
Analyzing genetic data on healthspan, parental lifespan, and longevity together, this study flagged haem metabolism as an aging-relevant pathway and — via Mendelian randomization — found evidence that genetically higher serum iron causally reduces healthy lifespan, while transferrin, which binds free iron, appeared protective. Because genetic evidence sidesteps many confounders of observational nutrition research, this is one of the stronger arguments for keeping iron in the moderate range.
The definitive review of ferroptosis — regulated cell death driven by iron-dependent accumulation of lipid hydroperoxides. It maps how iron homeostasis, glutathione-based antioxidant defenses, and lipid metabolism intersect, and connects ferroptotic death to neurodegenerative disease, stroke, and kidney injury. Mechanism papers do not prove dietary claims, but this is the biology underlying the concern about lifelong iron accumulation.
Frequently asked questions
Should I take iron just in case?
No — iron is the clearest test-first nutrient. Deficiency and excess are both harmful, the body cannot excrete surplus, and blind supplementation pushes you toward the wrong end of the U-curve. A ferritin test is cheap and settles the question.
What ferritin level should I aim for?
Longevity-oriented practitioners commonly target roughly 40–100 ng/mL. Levels below about 30 suggest depleted stores even without anemia, while persistently high values deserve a workup. One caveat: ferritin rises with inflammation, so interpret it alongside a marker like CRP.
How do I absorb more iron from food?
Pair plant (non-heme) iron with vitamin C — peppers, citrus, tomatoes — and keep coffee, tea, and calcium supplements a couple of hours away from iron-rich meals. Heme iron from meat and seafood absorbs several-fold better than plant iron regardless of what accompanies it.
My ferritin is high — what should I do?
First rule out inflammation and fatty liver, both of which raise ferritin without true iron overload, and ask your doctor about screening for hereditary hemochromatosis. If stores are genuinely high, regular blood donation lowers ferritin reliably and helps someone else in the process.
Does eating red meat cause iron overload?
For most people, no — the hormone hepcidin throttles iron absorption as stores fill. But heme iron absorption is less tightly regulated than plant iron, so heavy daily red meat intake can nudge stores upward over the years, and carriers of hemochromatosis variants are far more susceptible. An occasional ferritin check is sensible if red meat is a staple.
Track your iron intake
Biohack logs iron alongside 22 other longevity nutrients in every meal.