How much Iron should you take?

Dose by lab results. Iron bisglycinate is one preferred form (Mark Hyman); heme iron is another (Bryan Johnson). Do not supplement blind, without testing.

What form of Iron is best?

Iron bisglycinate: gentle on the stomach and well absorbed (Mark Hyman). Heme iron: animal-derived and highly bioavailable (Bryan Johnson). Liquid iron allows targeted dosing. Avoid ferrous sulfate if your stomach is sensitive.

Timing Protocol

When to Take Iron

What researchers say about when, how and with what to take iron, and how strong the evidence is.

The verdict on Iron overall

Leaning for

Iron supplements improve health only in people whose iron is low.

4 sources: 1 positive, 3 partly

Based on what researchers say in publicly available videos, not medical advice. Always consult your healthcare provider before starting, stopping, or changing any supplement.

Short answer

Take it with vitamin C to boost absorption; heme iron plus vitamin C is taken each morning in one routine (Bryan Johnson). An empty stomach absorbs best; take it with food if it upsets your stomach. Keep it away from calcium, coffee and tea, which block absorption.

Full Protocol

Timing: Take it with vitamin C to boost absorption; heme iron plus vitamin C is taken each morning in one routine (Bryan Johnson). An empty stomach absorbs best; take it with food if it upsets your stomach. Keep it away from calcium, coffee and tea, which block absorption.
Dosage: Dose by lab results. Iron bisglycinate is one preferred form (Mark Hyman); heme iron is another (Bryan Johnson). Do not supplement blind, without testing.
Form: Iron bisglycinate: gentle on the stomach and well absorbed (Mark Hyman). Heme iron: animal-derived and highly bioavailable (Bryan Johnson). Liquid iron allows targeted dosing. Avoid ferrous sulfate if your stomach is sensitive.
Notes: Always test before you supplement, because deficiency and overload both harm. Key tests: serum ferritin, serum iron, TIBC and transferrin saturation. Ferritin alone is not enough, because inflammation raises it (Peter Attia). Retest every 3-6 months while supplementing. Menstruating women, vegans and vegetarians, endurance athletes and people with gut absorption problems are most at risk of deficiency. Screen for hereditary hemochromatosis if ferritin stays high (Chris Kresser, on The Doctor's Farmacy).

What the evidence says about timing

One verdict, worked out from every counted mention. One dot is one source: a researcher or a study. Tap a dot to see its receipt.

positive partly neutral negative Each researcher and each study counts once per claim, however often they come up.

Not enough evidence

Taking iron with vitamin C increases how much is absorbed.

No counted mention yet.

Researchers say

No researcher counted yet.

Studies show

No study counted yet.

1 more not counted · see why

We could not tell where the evidence comes from. 1

Bryan Johnson's channel 00:56

Where the sources disagree

Built from every credited researcher and cited study on each claim.

Leaning for

Iron supplements improve health only in people whose iron is low.

Supports it 1 source: Chris Kresser, on The Dr. Hyman Show, at 43:09

Positive Video · Opinion

“I'm not a big fan of iron supplementation typically unless there's a reason you know unless we see that that patient has anemia”

Open the tape at 43:09 →
Partly 3 sources: Andrew Huberman, on Huberman Lab, at 1:26:18

Partly Video · Opinion

“iron can be toxic, too little means you're anemic. For women, the levels of iron that you want are somewhere between 25 and 100. And for men, somewhere between 30 and 150.”

Open the tape at 1:26:18 →

Dr Michael Breus, on Rangan Chatterjee's channel, at 1:26:48

Partly Video · Opinion

“all I do is fix those deficiencies. Sleep gets better and I don't have to do anything else.”

Open the tape at 1:26:48 →

Paula Hillard, on The Drive, at 2:23:10

Partly Video · Opinion

“yes if you're correcting deficiencies I think you can make a case for that.”

Open the tape at 2:23:10 →

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Full Iron Report

Every claim with its verdict and receipts

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Timing is half the equation

You know when to take Iron. A free account opens the interaction warnings for your whole stack. Pro adds chat about your own situation, drawn from 3,700+ hours of recorded interviews with 380 researchers and doctors, plus 48,500+ research studies.

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Iron verdict