Iron dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Iron is the most important 'no' on Aaron's stack. His ferritin, a blood test of stored iron, is 435. High ferritin means no iron at all, including inside a multivitamin. Low iron stores are for a doctor to fix, not a greens-powder decision.
Evidence grade for Iron: Preliminary. The rule: studied in people, but no published study has had people take it. The sum on this page: 1 human study where nobody was given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
1 human study where nobody was given it
2 effects reported, 2 unwanted, by people using it, not a trial
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Iron carries oxygen in your blood, and you need it. But too much iron is a disease. A blood test called ferritin shows how much iron you have stored. My ferritin is 435, so I take zero iron. That includes the iron hiding in multivitamins.
What people take it for
- Tiredness and low energy.
- Low iron stores or anemia.
- Because it came in a 'complete' multivitamin.
What studies in people showed
The key human study is about harm from too much iron. It looked at 422 treated people with an inherited iron overload disease. Those whose ferritin was over 1,000 when they were found were more likely to die from iron overload. That is a disease doctors manage, not a number to aim for. Guidelines say to read ferritin with the rest of the iron panel.
What people report
Reports, not study results
The good
- We have not collected user reports on this one yet.
The bad
- The risk this page flags: people with high iron stores who take iron anyway are adding to the problem.
- In an inherited iron overload disease, very high ferritin went with a higher risk of death.
Where these come from: We have no forum or clinic reports for this one. The risks listed come from the study and guideline on this page.
My bottom line
Never take iron without seeing your ferritin first. Mine is high, so I take none, and I read every label for hidden iron. If yours is low, fix it with your doctor, not a forum dose.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Nothing indexed yet
The 2 citations on this page do not report a result for any of the 36 goals indexed here. Most of what sits here is something else: a listing of a planned study, a study of how the body handles the drug, a safety report or a government record. None of those tests whether it works.
When this earns a spot
This page exists so people stop taking iron by default. The owner's ferritin (stored iron) is 435. High ferritin rules iron out. Low ferritin, confirmed by the rest of the iron tests, means talking with a doctor about topping up, including in pregnancy and with bleeding. It is never a greens powder decision.
Aaron's list, tier 2
Bloodwork that belongs beside the bottle
Ferritin, iron, TIBC or transferrin, saturation, and a full blood count. hs-CRP if ferritin is high.
Test again after about 90 days. If that blood number did not move, stop.
- Ferritin rises with inflammation.
- A multivitamin can hide iron.
Reading the number
High ferritin: no bottle. Low ferritin: see a doctor, not a forum dose. In people with inherited iron overload, over 1,000 went with a higher risk of death. That is not a number to aim for. It is a reason to get help.
What these tests mean: Ferritin, Iron panel.
What people typically order
Ask for the iron panel named above. Do not add an iron bottle while you wait for the result.
Show full evidence
What is Iron?
Iron is the most important 'no' on Aaron's stack. His ferritin, a blood test of stored iron, is 435. High ferritin means no iron at all, including inside a multivitamin. Low iron stores are for a doctor to fix, not a greens-powder decision.
Your body needs iron, and too much iron is a disease. This page exists because the default in the supplement aisle is to take iron without checking ferritin. That default is how people who already store plenty of iron pay for a bottle that works against them.
Aaron's published ferritin is 435. His rule is zero iron. In 422 treated people with HFE hemochromatosis, an inherited iron overload disease, a ferritin over 1,000 ug/L at diagnosis went with a higher risk of dying from iron overload. That is not a number for you to aim at. It is a reason to see a doctor when ferritin is high.
Low ferritin, with an iron panel and a low blood count to match, is the opposite talk. That is about topping up, pregnancy, bleeding or poor absorption. It is still not a forum dose. And it is still not a multivitamin you grabbed because it said 'complete'.
How does Iron work?
Iron sits in hemoglobin, which carries oxygen in your blood, in myoglobin in muscle, and in some enzymes. Ferritin stores it. A hormone called hepcidin controls how much you absorb. Inflammation raises ferritin, which can hide empty stores or make them look full. That is why ferritin is read with a full iron panel, and often with hs-CRP, a marker of inflammation.
What have studies in people found about Iron?
The human evidence this page needs is about harm from high ferritin, and how doctors check for it. It is not a bodybuilding loading plan.
- In 422 treated people with HFE hemochromatosis, high ferritin was how the risk of death from iron overload was sorted.
- Guidelines read ferritin and transferrin saturation (how full your iron carriers are) together. This site will not split them to make a bottle look safer.
- Aaron's 435 is published so the rule is concrete.
What this does not tell you: This page does not give iron doses for tiredness, 'low energy' or training. Topping up a real shortage is real, and it belongs with your doctor. A later update can cover pregnancy, and pills versus a drip, without turning this into a how-to.
The evidence, in charts
Fig. 1a · how many people
1study in people cited, but none says how many people took part
number of people not stated
We do not draw a total, because none of the studies in people on this page gives one. Read the sources below for what each study measured.
We read the number of people from the source lines on this page. Where a line gives no number, we count nothing for it. We do not guess.
Fig. 1b · evidence mix
1 of 2 sources here is a study in people. The rest is not.
- Study in people · done in people150%
- Review of studies · sums up other studies150%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
Sources here come from just two years, 2010 and 2012.
Too few different years on this page to draw a timeline. The newest source on file is from 2012, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Supplement
- Molecule weight
- Not on file
- Half-life
- None on file
- Chain length
- None on file
No amino acid sequence is on file for Iron, which is expected: a supplement is not built from amino acids.
The studies we cite
- Study in people2012Increased risk of death from iron overload among 422 treated probands with HFE hemochromatosis and serum levels of ferritin greater than 1000 ug/L at diagnosis.
Among people treated for an inherited iron overload disease, those who started with very high ferritin were more likely to die from iron overload. This is about a disease doctors manage. It is not a number for anyone to aim at.
Treated HFE hemochromatosis. Ferritin over 1,000 ug/L at diagnosis associated with higher death risk from iron overload. Clinician disease file, not a consumer target.
- Review of studies2010Clinical guidelines: HFE hemochromatosis-screening, diagnosis and management.
A guideline for doctors on screening for and managing inherited iron overload. Ferritin and transferrin saturation are tools for your doctor to read, not a do-it-yourself plan.
Guideline-level review of screening and management. Ferritin and transferrin saturation are clinician tools. They are not a self-protocol.
Common questions
Has Iron been tested in people?
Not in a completed trial cited here. 1 human study where nobody was given it. Iron is the most important 'no' on Aaron's stack. His ferritin, a blood test of stored iron, is 435. High ferritin means no iron at all, including inside a multivitamin. Low iron stores are for a doctor to fix, not a greens-powder decision.
What is the Iron dosage?
No human dose established. No published study on this page has given this compound to people and reported a result. 1 human study where nobody was given it
Is Iron FDA-approved?
Sold as a supplement, and as licensed medicines for iron shortage. It should not go into a longevity multivitamin by default when your ferritin (iron stores) is unknown or high.
My multi has iron. Is that fine?
Not if you have not seen your ferritin, and not if it is high. Aaron's rule is zero, including greens powders.
What if ferritin is low?
Then it becomes a talk with your doctor, along with the rest of the iron panel and a blood count. It does not become a grocery-aisle iron pill experiment.