Iron

Vitamin C dramatically increases iron absorption

2-3x better absorption when taken together

⟡ B-Complex (B12, Folate)

All needed for red blood cell production

Complete anemia prevention/treatment

✦ Molybdenum

Molybdenum supports iron metabolism and utilization

Better iron utilization and reduced sulfite sensitivity

⟡ Lactoferrin

Lactoferrin-bound iron is absorbed via specific receptors, offering a gentler iron delivery mechanism than ferrous sulfate with fewer GI side effects.

Improved iron bioavailability with reduced GI distress in iron-deficiency anemia

Top studies from 40+ peer-reviewed papers

📚meta-analysisn=7175

Anker SD et al. • Nature medicine (2025)

“This meta-analysis examined the effects of Iron.”

Key Findings:

All-cause mortality at 12 months and for the complete length of follow-up (HR = 0.82 (95% CI = 0.65-1.03)) and HR = 0.92 (95% CI = 0.80-1.07), respectively, indicated the overall safety of i.v. iron treatment.
These findings suggest that treating iron deficiency in patients with HF significantly reduces cardiovascular events and also suggests further investigation of optimal dosing of i.v. iron.
Treatment effects were greatest in the first year after randomization when the doses of i.v. iron provided are highest.

📚meta-analysisn=48971

Finkelstein JL et al. • The Cochrane database of systematic reviews (2024)

“Daily oral iron supplementation during pregnancy may reduce maternal anaemia and iron deficiency at term.”

Key Findings:

There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence).
Infant outcomes: Women taking iron supplements are probably less likely to have infants with low birthweight (5.2% versus 6.1%; RR 0.84, 95% CI 0.72 to 0.99; 12 trials, 18,290 infants; moderate-certainty evidence), compared to placebo or no iron supplementation.
However, the evidence is very uncertain for infant birthweight (MD 24.9 g, 95% CI -125.81 to 175.60; 16 trials, 18,554 infants; very low-certainty evidence).
The evidence is very uncertain about the effects of iron + folic acid on maternal iron-deficiency anaemia (10.8% versus 25%; RR 0.43, 95% CI 0.17 to 1.09; 1 trial, 131 women; very low-certainty evidence), or maternal deaths (no events; 1 trial; very low-certainty evidence).

📚meta-analysisn=722

Zhou Y et al. • Nutrients (2024)

“It was found that dietary factors were one of the major causes of anemia, and iron-containing supplements and nutrition counseling could be effective interventions to reduce the prevalence of anemia, ID, and IDA among Chinese pregnant women.”

Key Findings:

The results showed that the prevalence of anemia, ID, and IDA among pregnant women in China were 30.7% (95% CI: 26.6%, 34.7%), 45.6% (95% CI: 37.0%, 54.2%), and 17.3% (95% CI: 13.9%, 20.7%), respectively.
Generally, lower prevalence was observed in the economically more advanced eastern region of the country, while the prevalence of ID was higher in the eastern region than that in the western region.
The prevalence of anemia and IDA in rural areas was higher than that in urban areas, but ID prevalence was higher in urban areas.
In conclusion, the regional differences and urban-rural disparities in the prevalence of anemia indicate the need for more context-specific interventions to prevent and treat anemia.

📚meta-analysisn=572

Jensen MCH et al. • The Cochrane database of systematic reviews (2024)

“Intravenous iron probably reduces fatigue slightly in the early postpartum weeks (8 to 28 days) compared to oral iron tablets, but probably results in little to no difference after four weeks.”

Key Findings:

Intravenous iron versus oral iron supplementation The evidence is very uncertain about the effect of intravenous iron on mortality (risk ratio (RR) 2.95, 95% confidence interval (CI) 0.12 to 71.96; P = 0.51; I² = not applicable; 3 RCTs; 1 event; 572 women; very low-certainty evidence).
Intravenous iron probably results in a slight reduction in fatigue within 8 to 28 days (standardised mean difference -0.25, 95% CI -0.42 to -0.07; P = 0.006; I² = 47%; 2 RCTs; 515 women; moderate-certainty evidence).
Oral iron probably increases the risk of constipation compared to intravenous iron (RR 0.12, 95% CI 0.06 to 0.21; P < 0.001; I² = 0%; 10 RCTs; 1798 women; moderate-certainty evidence).
The evidence is very uncertain about the effect of intravenous iron on anaphylaxis or hypersensitivity (RR 2.77, 95% CI 0.31 to 24.86; P = 0.36; I² = 0%; 12 RCTs; 2195 women; very low-certainty evidence).

📚meta-analysisn=920

Compare with Others Find Based on Your Goals

Shah AA et al. • JAMA network open (2021)

“In this large systematic review and meta-analysis, intravenous iron was associated with an increased risk of infection.”

Key Findings:

Intravenous iron was associated with an increased risk of infection when compared with oral iron or no iron (RR, 1.17; 95% CI, 1.04-1.31; I2 = 37%; moderate certainty of evidence).
In this large systematic review and meta-analysis, intravenous iron was associated with an increased risk of infection.
Well-designed studies, using standardized definitions of infection, are required to understand the balance between this risk and the potential benefits.

View all 40+ studies

What would you like to do next?

Related Supplements

Zn9.0

Zinc

Involved in 300+ enzymatic reactions — supports immune defense, testosterone production, wound healing, and sleep quality.

I9.0

Iodine

Essential trace mineral for thyroid hormone production — deficiency is common and affects metabolism, energy, and cognition.

Se9.0

Selenium

Required for selenoprotein production that regulates thyroid hormones, powers glutathione peroxidase, and strengthens immune defense.

CA8.8

Calcium

8.8/10

Builds and maintains bone density while supporting muscle contraction, nerve signaling, and cardiovascular function.

Fe9.0

Iron

mineral

Iron (Various Forms)

Essential mineral for oxygen transport and energy production — critical for those with deficiency, especially women and athletes.

bodyenergymineralanemiawomen's healthathletes

40+ studies

Evidence

Reviewed 19 days ago

moderate

Safety

18-45mg elemental iron for deficiency (varies by severity)

Dose

12-24 weeks

Time to Effect

Ferrous bisglycinate (gentle, well-absorbed) or iron protein succinylate

Best Form

Mechanisms of Action

🫁

Oxygen Transport

Essential component of hemoglobin

⚡

Energy Production

Required for mitochondrial function

Biological PathwayBeta

How Iron works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.

Supplement

Molecular Target

Biological Process

Health Outcome

Strong

Moderate

Emerging

strong

moderate

emerging

Tap node to isolate • Pinch to zoom • Tap edge for research

Recommended Dose

18-45mg elemental iron for deficiency (varies by severity)

18mg elemental iron45mg elemental iron

Loading: Every-other-day dosing may improve absorption

Optimal Timing

On empty stomach if tolerated
Away from tea, coffee, dairy

Can be taken without food

Available Forms

Form	Type
💊Ferrous bisglycinate (gentle, well-absorbed) or iron protein succinylate	Recommended
💊Ferrous sulfate (cheapest but harsh)	Alternative
💊Ferrous fumarate	Alternative
💊Heme iron (from animal source)	Alternative

Bisglycinate causes less GI upset. Ferrous sulfate is effective but causes more constipation. Check 'elemental iron' content, not total weight.

Duration

Minimum: 12 weeks

Optimal: 24 weeks

Cycling: Continue 3-6 months after ferritin normalizes, then retest. Do NOT supplement long-term without monitoring.

Note: Best absorbed on empty stomach with vitamin C. If GI upset, take with small amount of food. Avoid taking with calcium, tea, coffee within 2 hours.

⚡

Energy Restoration

Improved energy levels when deficient

⏱️ 2-4 weeks

85% of users notice thispositive

🧠

Cognitive Function

Better focus and mental clarity

⏱️ 4-8 weeks

70% of users notice thispositive

🏃

Exercise Performance

Improved endurance capacity

⏱️ 4-12 weeks

65% of users notice thispositive

ModerateMax safe dose: 18-27 mg/day in pregnancy; 9-10 mg/day in lactation

🟡

Pregnant women

Higher needs (27mg/day); follow prenatal guidance

🟡

Men and postmenopausal women

Lower risk of deficiency — test before supplementing

Who Should NOT Take This

Hemochromatosis or iron overload
Repeated blood transfusions
Adequate iron stores (test first!)

Drug Interactions

Thyroid medications (levothyroxine)severe

Reduces absorption — take 4+ hours apart

Antacids, PPIsmoderate

Reduce iron absorption

Antibiotics (fluoroquinolones, tetracyclines)severe

Iron reduces antibiotic absorption — separate by 2+ hours

levodopasevere

Reduced levodopa effectiveness, worsening Parkinson symptoms

ciprofloxacinsevere

Significantly reduced antibiotic effectiveness

risedronatesevere

Reduced drug effectiveness for osteoporosis

ofloxacinsevere

Up to 90% reduction in antibiotic absorption

demeclocyclinesevere

Antibiotic treatment failure

deferoxaminesevere

Counteracts therapeutic effect of iron chelation

Possible Side Effects

Constipation

moderatecommon

Tip: Use bisglycinate form; add magnesium; increase fiber/water

Nausea/GI upset

mildcommon

Tip: Take with food; switch to gentler form

Dark stools

mildcommon

Tip: Normal effect of iron — not concerning

Warnings

ALWAYS test iron levels before supplementing — excess iron is harmful
Keep away from children — iron overdose is dangerous
Do NOT take with calcium, tea, or coffee
Monitor ferritin to avoid iron overload

✦ Vitamin C

Vitamin C dramatically increases iron absorption

2-3x better absorption when taken together

⟡ B-Complex (B12, Folate)

All needed for red blood cell production

Complete anemia prevention/treatment

✦ Molybdenum

Molybdenum supports iron metabolism and utilization

Better iron utilization and reduced sulfite sensitivity

⟡ Lactoferrin

Lactoferrin-bound iron is absorbed via specific receptors, offering a gentler iron delivery mechanism than ferrous sulfate with fewer GI side effects.

Improved iron bioavailability with reduced GI distress in iron-deficiency anemia

Top studies from 40+ peer-reviewed papers

📚meta-analysisn=7175

Anker SD et al. • Nature medicine (2025)

“This meta-analysis examined the effects of Iron.”

Key Findings:

All-cause mortality at 12 months and for the complete length of follow-up (HR = 0.82 (95% CI = 0.65-1.03)) and HR = 0.92 (95% CI = 0.80-1.07), respectively, indicated the overall safety of i.v. iron treatment.
These findings suggest that treating iron deficiency in patients with HF significantly reduces cardiovascular events and also suggests further investigation of optimal dosing of i.v. iron.
Treatment effects were greatest in the first year after randomization when the doses of i.v. iron provided are highest.

📚meta-analysisn=48971

Finkelstein JL et al. • The Cochrane database of systematic reviews (2024)

“Daily oral iron supplementation during pregnancy may reduce maternal anaemia and iron deficiency at term.”

Key Findings:

There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence).
Infant outcomes: Women taking iron supplements are probably less likely to have infants with low birthweight (5.2% versus 6.1%; RR 0.84, 95% CI 0.72 to 0.99; 12 trials, 18,290 infants; moderate-certainty evidence), compared to placebo or no iron supplementation.
However, the evidence is very uncertain for infant birthweight (MD 24.9 g, 95% CI -125.81 to 175.60; 16 trials, 18,554 infants; very low-certainty evidence).
The evidence is very uncertain about the effects of iron + folic acid on maternal iron-deficiency anaemia (10.8% versus 25%; RR 0.43, 95% CI 0.17 to 1.09; 1 trial, 131 women; very low-certainty evidence), or maternal deaths (no events; 1 trial; very low-certainty evidence).

📚meta-analysisn=722

Zhou Y et al. • Nutrients (2024)

“It was found that dietary factors were one of the major causes of anemia, and iron-containing supplements and nutrition counseling could be effective interventions to reduce the prevalence of anemia, ID, and IDA among Chinese pregnant women.”

Key Findings:

The results showed that the prevalence of anemia, ID, and IDA among pregnant women in China were 30.7% (95% CI: 26.6%, 34.7%), 45.6% (95% CI: 37.0%, 54.2%), and 17.3% (95% CI: 13.9%, 20.7%), respectively.
Generally, lower prevalence was observed in the economically more advanced eastern region of the country, while the prevalence of ID was higher in the eastern region than that in the western region.
The prevalence of anemia and IDA in rural areas was higher than that in urban areas, but ID prevalence was higher in urban areas.
In conclusion, the regional differences and urban-rural disparities in the prevalence of anemia indicate the need for more context-specific interventions to prevent and treat anemia.

📚meta-analysisn=572

Jensen MCH et al. • The Cochrane database of systematic reviews (2024)

“Intravenous iron probably reduces fatigue slightly in the early postpartum weeks (8 to 28 days) compared to oral iron tablets, but probably results in little to no difference after four weeks.”

Key Findings:

Intravenous iron versus oral iron supplementation The evidence is very uncertain about the effect of intravenous iron on mortality (risk ratio (RR) 2.95, 95% confidence interval (CI) 0.12 to 71.96; P = 0.51; I² = not applicable; 3 RCTs; 1 event; 572 women; very low-certainty evidence).
Intravenous iron probably results in a slight reduction in fatigue within 8 to 28 days (standardised mean difference -0.25, 95% CI -0.42 to -0.07; P = 0.006; I² = 47%; 2 RCTs; 515 women; moderate-certainty evidence).
Oral iron probably increases the risk of constipation compared to intravenous iron (RR 0.12, 95% CI 0.06 to 0.21; P < 0.001; I² = 0%; 10 RCTs; 1798 women; moderate-certainty evidence).
The evidence is very uncertain about the effect of intravenous iron on anaphylaxis or hypersensitivity (RR 2.77, 95% CI 0.31 to 24.86; P = 0.36; I² = 0%; 12 RCTs; 2195 women; very low-certainty evidence).

📚meta-analysisn=920

Compare with Others Find Based on Your Goals

Shah AA et al. • JAMA network open (2021)

“In this large systematic review and meta-analysis, intravenous iron was associated with an increased risk of infection.”

Key Findings:

Intravenous iron was associated with an increased risk of infection when compared with oral iron or no iron (RR, 1.17; 95% CI, 1.04-1.31; I2 = 37%; moderate certainty of evidence).
In this large systematic review and meta-analysis, intravenous iron was associated with an increased risk of infection.
Well-designed studies, using standardized definitions of infection, are required to understand the balance between this risk and the potential benefits.

View all 40+ studies

What would you like to do next?

Related Supplements

Zn9.0

Zinc

Involved in 300+ enzymatic reactions — supports immune defense, testosterone production, wound healing, and sleep quality.

I9.0

Iodine

Essential trace mineral for thyroid hormone production — deficiency is common and affects metabolism, energy, and cognition.

Se9.0

Selenium