A
Grade A💊 18-45mg daily when deficient🎯 11 primary uses🔗 1 synergy⚠️ Review warnings
Levels upNutrition+50 pts
Overview
Essential for oxygen transport and immune cell function, but excess can feed pathogens. Important to test before supplementing.
Primary Uses
Hair lossHair growthFerritin supportEnergyOxygen transportFatigueAnemia preventionImmune cell functionAnemia treatmentImmune functionCognitive function
Frequently Asked About Iron
How much Iron should I take?
The typical effective range is 18-30 mg. Individual needs vary based on age, body weight, diet, and goals — start at the lower end and adjust based on response. Always consult a healthcare provider before starting a new supplement.
When is the best time to take Iron?
Empty stomach or with vitamin C. Consistency matters more than perfect timing — pick a daily anchor (e.g. with breakfast or before bed) and stick with it.
Should I take Iron with food?
Optional, may reduce absorption.
What is the best form of Iron?
Iron Bisglycinate is generally the best-absorbed form (Iron chelated with glycine (Ferrochel)). Cheaper forms exist but often deliver less usable Iron per dose.
Does Iron interact with medications?
Yes — known interactions include Separate from thyroid meds and Antacids reduce absorption. If you take any prescription medication, talk to your doctor or pharmacist before starting Iron.
What does Iron pair well with?
Iron stacks well with Vitamin C — these combinations either improve absorption or work synergistically toward common goals.
Who should not take Iron?
Iron should be avoided or used with caution by people with Hemochromatosis and Iron overload. Pregnant or breastfeeding women should consult a healthcare provider before use.
Compare Forms
8 formsDifferent chemical forms vary in absorption, side effects, and best use cases. Higher bioavailability scores indicate better absorption.
Iron Bisglycinate
HIGH 100Iron chelated with glycine (Ferrochel)
Best for:Iron deficiencySensitive stomachsPregnancy
💡 Excellent absorption. Dramatically reduced GI side effects.
✅ Pros
- • Best tolerated
- • High absorption
- • No constipation
- • No nausea
⚠️ Cons
- • More expensive
- • Lower elemental iron per pill
📝 Ferrochel brand - best choice for most people
Iron Glycinate
HIGH 100Iron chelated with glycine
Best for:Iron deficiencyGeneral supplementation
💡 Excellent absorption with minimal side effects
✅ Pros
- • Great absorption
- • Gentle
- • Well-tolerated
⚠️ Cons
- • Higher cost
📝 Same as bisglycinate
Ferrous Fumarate
HIGH 85Iron salt with fumaric acid
Best for:Iron deficiencyHigher dose needs
💡 Good absorption. High elemental iron content.
✅ Pros
- • High elemental iron
- • Effective
- • Reasonably priced
⚠️ Cons
- • Can cause constipation
- • GI upset possible
📝 Good option if glycinate too expensive
Ferrous Gluconate
GOOD 80Iron salt with gluconic acid
Best for:Mild iron deficiencySensitive stomachs
💡 Good absorption. Gentler than sulfate.
✅ Pros
- • Better tolerated than sulfate
- • Reasonable absorption
⚠️ Cons
- • Lower elemental iron
📝 Middle ground option
Carbonyl Iron
GOOD 75Highly purified metallic iron
Best for:Those who need pure ironLower toxicity risk
💡 Slow, sustained absorption. Very low toxicity risk.
✅ Pros
- • Low toxicity risk
- • Slow release
- • Pure form
⚠️ Cons
- • Slower to raise levels
- • May need higher doses
📝 Safest form - low overdose risk
Ferrous Sulfate
GOOD 70Most common prescription iron form
Best for:Medical treatment of anemiaWhen prescribed
💡 Good absorption but significant GI side effects
✅ Pros
- • Inexpensive
- • Widely available
- • Effective
⚠️ Cons
- • Constipation
- • Nausea
- • Dark stools
- • GI upset common
📝 Common but poorly tolerated - try glycinate first
Ferric Citrate
GOOD 70Ferric iron with citric acid
Best for:Kidney disease patientsPhosphate binding
💡 Moderate absorption. Also binds phosphate.
✅ Pros
- • Phosphate binding for kidney patients
⚠️ Cons
- • Lower absorption than ferrous forms
📝 Mainly for kidney disease (Auryxia)
Ferric Iron
LOW 55Oxidized (Fe3+) form of iron
Best for:Specific medical uses
💡 Poor absorption - must be reduced to ferrous form
✅ Pros
- • Less reactive
⚠️ Cons
- • Poor absorption
- • Less effective
📝 Ferrous (Fe2+) forms preferred
Dosage
Typical range
18-45mg daily when deficient
Timing
Empty stomach or with vitamin C
With food
Optional, may reduce absorption
Dose Tiers
RDA / DV
8-18 mg
Moderate
18-30 mg
Therapeutic
60-200 mg elemental
Upper Limit
45 mg
Duration
Until levels normalize
Special Populations
Women, vegetarians
Research & Studies
Landmark clinical studies on Iron. Each title links to a plain-English breakdown — what the study shows, what its limitations are, and how to read around them.
- Oral iron supplements increase hepcidin and decrease iron absorption from daily or twice-daily doses in iron-depleted young women
Landmark absorption study showing iron supplements taken daily (or twice-daily) trigger hepcidin elevation that blocks subsequent absorption — supporting alternate-day dosing as more efficient for iron repletion.
- Iron bioavailability and dietary reference values
Reviews enhancers (vitamin C, meat) and inhibitors (phytate, polyphenols, calcium) of non-heme iron absorption, providing the mechanistic basis for pairing iron with vitamin C and separating it from tea/coffee.
Browse all curated studies →
Mechanism of Action
- • Hemoglobin component
- • Myoglobin in muscles
- • Electron transport chain
- • Enzyme cofactor
Evidence Quality
Evidence Grade A
Essential mineral critical for oxygen transport
Safety & Contraindications
Serious Warnings
- • Toxicity at high doses
- • Hemochromatosis
Contraindications
- • Hemochromatosis
- • Iron overload
Common Side Effects
- • Constipation
- • Nausea
- • Dark stools
Pregnancy & Breastfeeding
Often needed
Liver & Kidney Notes
Test levels first
Interactions
💊 Medications
- • Separate from thyroid meds
- • Antacids reduce absorption
🧪 Supplements
- • Vitamin C enhances
- • Calcium inhibits
🍽️ Food & Alcohol
- • Meat best source
Stacking & Synergies
Pairs Well With
Best Goal Synergies
EnergyAnemia
Buying Guide
What to Look For
- • Gentle form like bisglycinate
Standardization Markers
Elemental iron stated
Adulteration risk
Low
Practical Notes
- • Test ferritin before supplementing
- • Target ferritin 70+ for hair
- • ALWAYS test before supplementing
- • Bisglycinate is gentlest form
- • Don't supplement if not deficient
- • Bisglycinate gentlest on stomach
- • Test levels before supplementing
- • Bisglycinate gentlest form
Tags
mineralhairessentialferritinenergyoxygenimmuneblood
Top Products with Iron
Highest-scored catalog products containing Iron, ranked by our scoring engine.
Iron BisglycinateThorne96
Grass-Fed Whey Protein IsolateTransparent Labs95
ForHer Hormone Balance and Longevity Multivitamin for WomenComplement89
Basic PrenatalThorne88
Related Guides
In-depth guides covering Iron — protocols, comparisons, and use cases.
More in Mineral
Other ingredients in the Mineral category.
Boron
Trace mineral supporting bone health, cognitive function, and hormone metabolism. May support testosterone in deficient states.
Calcium
Essential mineral for bone health, muscle function, nerve signaling, and blood clotting.
Calcium Carbonate
Common, economical calcium form with highest elemental calcium percentage. Requires stomach acid for absorption.
Calcium Citrate
Well-absorbed calcium form that doesn't require stomach acid. Better for those on acid-reducing medications.
Chloride
Essential electrolyte mineral that works with sodium and potassium to maintain fluid balance, nerve transmission, and stomach acid production.
Chromium Picolinate
Trace mineral for insulin sensitivity and blood sugar regulation. Popular for carb cravings.
Last reviewed: September 2026 by the Formulate Research Team. Sources cited above; methodology and scoring criteria published here.
Cite this page
Formulate Research Team. (2026, September). Iron — Evidence-Based Supplement Guide. Formulate Supplement Encyclopedia. https://app.formulate-health.app/learning/supplements/iron
Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.