Iron B

Helps in deficiency; without deficiency it is useless and harmful

HealthEndurance Recompositionthere are certified formsnote: doping control

Citable fact

«Iron» — evidence level B. Dosage: The doctor selects doses based on ferritin, transferrin and hemoglobin; typically 40–100 mg of elemental iron per day, and every other day if it is not tolerated. Forms: sulfate, fumarate, bisglycinate. Source: PMID 39536912, permanent link to the source in the list below.

How it works

Iron is required for the synthesis of hemoglobin and myoglobin, for oxygen transport and for the work of oxidative enzymes in muscle. Deficiency without anemia already reduces endurance.

Dosage and intake

Dosage

The doctor selects doses based on ferritin, transferrin and hemoglobin; typically 40–100 mg of elemental iron per day, and every other day if it is not tolerated. Forms: sulfate, fumarate, bisglycinate.

When to take

On an empty stomach or with vitamin C; 2 hours before or 4 hours after tea, coffee, calcium and iron-containing products. Every-other-day intake may improve absorption.

Doses are given for adults. For profiles under 18 the app does not show doses, and during pregnancy and lactation the personal calculation is replaced by advice to consult a doctor.

Forms

Sulfate, fumarate, gluconate and bisglycinate have been studied. Bisglycinate is tolerated better, but there is less data on how fast it restores stores; data on “liquid iron” and heme forms are limited.

What is confirmed

Systematic review in female athletes: in iron deficiency, therapy improves aerobic performance
Less fatigue and better exercise tolerance in anemia
In athletes with normal stores, supplementation does not improve performance
Especially relevant for women, long-distance runners and vegetarians

Adverse effects and limitations

Constipation, nausea, dark stools, metallic taste
Overdose is life-threatening, especially in children: keep out of reach
Excess iron increases oxidative stress and damages the liver
Taking it without a blood test can mask other causes of anemia

Interactions

Calcium, tea, coffee, milk and antacids reduce absorption
Tetracyclines, fluoroquinolones and bisphosphonates bind to iron — separate by at least 2 hours
Vitamin C improves absorption; taking it together with zinc impairs the uptake of both

Who must not use it

Under 18 years: Only for confirmed deficiency and as prescribed by a doctor.
Pregnancy and lactation: Often prescribed when indicated; self-administration without tests is not recommended.
hemochromatosis
thalassemia
hemosiderosis
chronic inflammatory diseases

Sources

Open in the app

This page holds reference data with links to studies. In the app you can calculate calories and macros for your goal, build a personal supplement stack and review weekly training volume.

Open «Iron» in the app