Supplement
Iron
Drug-grade for the deficient, pointless-to-harmful for everyone else, and the test decides which you are.
Iron is the oxygen-carrying core of hemoglobin and a cofactor across energy metabolism. We grade Iron B- on evidence and B for worth-it at about $5-10 per month.
Evidence
Worth it
Typical cost: $5-10/month
What it does
Iron is the oxygen-carrying core of hemoglobin and a cofactor across energy metabolism. It is supplemented as ferrous salts or gentler chelates. No ingredient in this library has a wider gap between its value in the right person and its risk in the wrong one, and the queue that commissioned this record demanded that be said plainly.
What the research says
Treats iron deficiency and iron-deficiency anemia, unequivocally
Evidence: strong. Iron deficiency is the most common nutritional deficiency in the world. Oral iron reliably raises hemoglobin and ferritin in deficient people; this is drug-grade, guideline-anchored medicine, the strongest treatment claim in this library's mineral section. Symptoms that prompt testing: fatigue, pallor, breathlessness, restless legs, hair shedding, and reduced exercise tolerance.
Improves fatigue in non-anemic people whose ferritin is low
Evidence: moderate. Randomized trials in fatigued women with low ferritin but normal hemoglobin (Favrat 2014; Vaucher 2012) found iron improved fatigue versus placebo. The boundary is the blood test: benefit tracks documented low iron stores, not the symptom of tiredness by itself.
No benefit, and accumulating risk, in people whose iron is already sufficient
Evidence: moderate. The body has no regulated way to excrete excess iron, so unneeded supplementation accumulates. In the landmark Pemba trial, routine iron given to iron-replete children in a malaria-endemic region increased serious adverse events, the field's standing warning against untargeted iron. In adults, excess shows up as GI distress acutely and, in iron-loading conditions like hemochromatosis, organ damage over years.
Iron grades like a medicine because it behaves like one: powerfully effective for the deficiency it treats, measurably helpful for fatigue when stores are low even without anemia, and pointless-to-harmful when stores are full, with the harm mechanism (no excretion pathway) built into human physiology. The grade reflects correct-use value: high for the large population that is genuinely deficient, nothing for everyone else, and the record is written so the test comes before the purchase.
The week's longevity and biohacking news.
This grade for Iron rests on the record above. When a new result changes that record, the grade changes with it, and the Thursday email is where the change lands first: the week's longevity and biohacking news, in plain English, linked back to the reasoning on this page.
The week's longevity and biohacking news. Every story graded against the evidence. Free. Unsubscribe anytime.
Every grade follows a published rubric, and sponsors never change one. When the evidence moves a grade, Thursday is where you hear it first, before you renew a stack that stopped earning its cost.
Is it worth it?
Evidence (B-) clears the leaderboard floor, and the worth-it grade is the derived value at this price: about $7 a month at treatment doses. The grade applies to iron bought after a test shows deficiency; untested purchase has no such value. Derived from the October 2026 worth-it model.
Typical cost
$5-10/month
Common form, not a brand recommendation
Dosage context established
Test first: ferritin and hemoglobin decide whether iron is indicated at all. Do not take iron for energy without a blood test showing you need it; excess iron accumulates and harms. When indicated, standard treatment is about 40 to 65 mg of elemental iron once daily, and alternate-day dosing absorbs comparably with fewer side effects because it works with the hepcidin cycle (Stoffel trials). Take it away from calcium supplements, tea, coffee, and thyroid medication, all of which block absorption. Recheck levels after 8 to 12 weeks and stop when replete unless a clinician says otherwise.
Worth-it leaderboard
Iron ranks #16 for worth-it.
That rank comes from the gated model on the leaderboard: evidence grade B- or better, purchasable, and useful beyond a single occasion, then scored on evidence against monthly cost.
See the full worth-it leaderboard →
When the evidence moves a grade, this ranking moves with it. Thursday is where you hear it first.
Safety notes
Overdose is the pediatric emergency in this category: iron tablets are a leading cause of fatal poisoning in young children, so treat the bottle like medicine around kids, because it is. In adults: constipation, nausea, and black stools are common and benign; the serious risks are slower (iron loading in hemochromatosis, which is common and often undiagnosed, and masking the cause of a deficiency, which in older adults can be gastrointestinal blood loss that needs investigation, not just replacement). Anyone found iron-deficient after midlife should expect a clinician to ask why, and that question matters more than the supplement.
Longevity Lab Report
Iron news. Graded when it happens.
The grade on this page stays free. The email carries the news on iron: expert moves, dose changes, and what is working, in plain English every Thursday.
Changelog
Last updated 2026-10-23
- 2026-10-23|Graded from the deficiency treatment literature, the non-anemic fatigue trials, and the Pemba trial's warning on untargeted supplementation. This is a test-first record: the caution travels inside the dosage guidance, not only in the safety notes, because readers and answer engines lift dosage blocks alone.
- 2026-10-23|Listed under energy, matching this record's graded fatigue findings in iron-deficient people.