Iron
Iron is an essential mineral. 165 peer-reviewed studies are available in our database. Common forms include Ferrous Sulfate, Ferrous Fumarate, Iron Bisglycinate.
Content reviewed by Zynava Research Team · Last updated February 2026 · Editorial policy
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Explore iron supplements and browse options based on ingredient research.
What Is Iron?
Iron is an essential mineral critical for oxygen transport in the blood (as part of hemoglobin) and energy production in cells.
Key fact: Bisglycinate is a chelated form often used for tolerability.
What Research Has Examined
- Often discussed for its essential role in red blood cell production and oxygen transport
- Commonly mentioned in relation to energy levels and combating fatigue from deficiency
- Frequently explored for its importance during pregnancy and menstruation
- Sometimes studied for its role in cognitive function and development
Iron Supplement Forms
Ferrous Bisglycinate
Chelated form; often cited for gentleness and absorption
Ferrous Sulfate
Most common and affordable; may cause more GI side effects
Ferrous Gluconate
Moderate absorption; gentler than sulfate for some
Carbonyl Iron
Highly pure elemental iron; slower absorption, lower toxicity risk
Heme Iron
Animal-derived form; may absorb more efficiently than non-heme
Typical Dosage Range
Supplement labels typically list 18–65 mg per serving The RDA is 8 mg for men and 18 mg for premenopausal women
Optimal dosage may vary based on individual factors. Always consult a healthcare professional before starting any supplement regimen.
Safety & Considerations
- Should only be supplemented when deficiency is identified or at risk
- Excess iron can be toxic and may cause gastrointestinal distress
- Some forms are gentler on the stomach than others
- Can interact with many medications including antacids, thyroid medications, and antibiotics
- Individuals with hemochromatosis must avoid iron supplements
Explore Iron Supplements
Use our research tool to explore iron supplements and see what studies have examined.
Research Studies on Iron
Our database contains 165 peer-reviewed studies examining iron. Below are selected recent studies:
Health Goals Associated with Iron
Research has examined iron in relation to several health areas:
Related Supplements
Frequently Asked Questions About Iron
What is Iron?
Iron is an essential mineral critical for oxygen transport in the blood (as part of hemoglobin) and energy production in cells.
What are the different forms of Iron?
Iron is available in several supplemental forms including Ferrous Sulfate, Ferrous Fumarate, Iron Bisglycinate, Heme Iron. Bisglycinate is a chelated form often used for tolerability.
What health goals is Iron associated with?
Research has examined iron in relation to several health areas including anemia, restless legs. The best supplement depends on individual factors — consult a healthcare professional for personalized guidance.
Is Iron safe to take?
Should only be supplemented when deficiency is identified or at risk Excess iron can be toxic and may cause gastrointestinal distress Some forms are gentler on the stomach than others Can interact with many medications including antacids, thyroid medications, and antibiotics Individuals with hemochromatosis must avoid iron supplements Always consult a healthcare provider before starting any supplement, especially if you take medications or have existing health conditions.
Natural Food Sources of Iron
Dietary sources of iron offer the advantage of providing the nutrient alongside other beneficial compounds naturally present in food. Here is a look at the most significant food sources and practical tips for optimizing your intake.
- Red meat — A 3 oz serving of beef provides about 15% of the daily value as highly absorbable heme iron
- Oysters — An excellent source of heme iron
- Lentils — One cup of cooked lentils provides about 35% of the daily value as non-heme iron
- Spinach — A cup of cooked spinach provides about 35% of the daily value, though as non-heme iron
- Fortified cereals — Many breakfast cereals are fortified with iron
- Dark chocolate — One ounce of dark chocolate provides about 20% of the daily value
Dietary Context
Iron exists in food as two types: heme iron (found in animal products) and non-heme iron (found in plant foods and fortified products). Heme iron is absorbed 2-3 times more efficiently than non-heme iron. Iron deficiency is one of the most common nutritional deficiencies worldwide, particularly among women of childbearing age.
Absorption: Food vs. Supplements
Non-heme iron absorption is strongly influenced by other dietary components. Vitamin C can dramatically increase non-heme iron absorption — consuming just 75 mg of vitamin C with a meal can increase iron absorption by 3-4 times. Conversely, tannins in tea and coffee, calcium, and phytates can inhibit iron absorption.
Practical Tips
- Pair plant-based iron sources with vitamin-C-rich foods (bell peppers, citrus, tomatoes)
- Avoid drinking tea or coffee with iron-rich meals, as tannins reduce absorption
- Cast-iron cookware can contribute small amounts of iron to food, especially with acidic dishes
How to Take Iron
Getting the most from iron supplementation involves more than just choosing the right product. When and how you take it can significantly affect absorption and effectiveness.
Best time to take: Morning on an empty stomach for best absorption
With or Without Food
Ideally taken on an empty stomach (1 hour before or 2 hours after eating) for maximum absorption. If stomach upset occurs, taking with a small amount of food is acceptable, though absorption will be reduced.
How Often
Typically once daily. Some research suggests alternate-day dosing may actually improve absorption efficiency compared to daily dosing.
Practical Tips
- Take with vitamin C (orange juice, bell peppers) to dramatically enhance absorption
- Avoid taking with calcium supplements, dairy, coffee, or tea — these significantly reduce iron absorption
- Wait at least 2 hours between iron and other mineral supplements
- Alternate-day dosing has shown promise for improving absorption while reducing side effects
Important Interactions
- Antacids and proton pump inhibitors reduce iron absorption
- Iron can reduce the effectiveness of levothyroxine and certain antibiotics
- Tannins in tea and coffee can reduce iron absorption by 50-90%
This is not an exhaustive list of interactions. Always consult a healthcare provider or pharmacist about potential interactions with your specific medications and health conditions.
Where to Find Iron Supplements
If you are considering iron supplementation, choosing a quality product from a reputable retailer is an important step. Here are some trusted options where you can browse and compare iron supplements.
How to Choose a Quality Iron Supplement
- Look for Good Manufacturing Practice (GMP) certification on the label
- Check whether the product uses the specific form of the ingredient you are looking for
- Review customer feedback and ratings for real-world product experiences
- Consider the supplement form (capsule, powder, liquid, gummy) that best suits your preference
To explore supplements by ingredient or health goal, try our AI Supplement Advisor.
Research Highlights: Iron
Researchers have investigated iron across 2 clinical trials, 2 reviews, 1 meta-analysis, 1 systematic review, with publications spanning 2025 to 2026. The summaries below highlight key findings from these studies. As with all research, results should be considered within the broader body of evidence and may not apply to every individual.
Oral iron supplements for children in malaria-endemic areas
Published in Cochrane Database Syst Rev. Study from 2026.
Source: View full study on PubMed
The benefits and harms of oral iron supplementation in non-anaemic pregnant women: a systematic review and meta-analysis
Published in Fam Pract. Study from 2025. Comprehensive analysis combining multiple studies.
Source: View full study on PubMed
Iron supplementation for infants in the NICU: What preparation, how much, and how long is optimal?
Published in Semin Fetal Neonatal Med. Study from 2025.
Source: View full study on PubMed
A review of the effect of iron supplementation on the gut microbiota of children in developing countries and the impact of prebiotics
Published in Nutr Res Rev. Study from 2025.
Source: View full study on PubMed
Dietary Heme Iron: A Review of Efficacy, Safety and Tolerability
Published in Nutrients. Study from 2025.
Source: View full study on PubMed
Systematic review on supplementation, fortification, and food-based interventions for preventing iron deficiency anemia in low- and middle-income countries
Published in Asia Pac J Clin Nutr. Study from 2025. Comprehensive analysis combining multiple studies.
Source: View full study on PubMed
The research summaries above are based on published peer-reviewed studies and are provided for informational purposes only. Study findings may not apply to all individuals, and the presence of a study summary does not constitute an endorsement of iron for any specific health condition. Always consult a qualified healthcare professional before making decisions based on research findings.
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