Mineral
Iron (as Ferrous Fumarate)
Also known as: ferrous fumarate, iron(II) fumarate, Fe2+
Ferrous fumarate is a highly bioavailable form of iron used to prevent and treat iron deficiency anemia by supporting oxygen transport and energy metabolism. It is one of the most absorbable iron salts available.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every Iron (as Ferrous Fumarate) product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Thorne Iron Bisglycinate | 96 A | $0.27 |
| 2 | Transparent Labs Grass-Fed Whey Protein Isolate | 95 A | $2.00 |
| 3 | Complement ForHer Hormone Balance and Longevity Multivitamin for Women | 89 A | $0.67 |
| 4 | Thorne Basic Prenatal | 88 A | $1.23 |
| 5 | Ritual Essential Prenatal | 88 A | $0.65 |
| 6 | Pure Encapsulations Iron-C | 87 A | $0.32 |
| 7 | Solgar Gentle Iron | 87 A | $0.09 |
| 8 | Transparent Labs Multivitamin | 86 A- | $1.33 |
| 9 | Complement Restore | 86 A- | $1.90 |
| 10 | Seed AM-02™ Energy + Focus Supplement | 86 A- | $1.17 |
| 11 | Garden of Life Primal Defense Ultra | 86 A- | $0.56 |
| 12 | Garden of Life Organics Prenatal Multi | 86 A- | $1.14 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much Iron (as Ferrous Fumarate) should I take?
The typical range is 18-27 mg elemental iron daily (adult women); 8-11 mg daily (adult men). treatment duration depends on deficiency severity; typically several months for repletion
When should I take Iron (as Ferrous Fumarate)?
take on empty stomach for optimal absorption, or with small amount of food if GI upset occurs. preferably without food, but avoid dairy, calcium, and coffee which reduce absorption.
Which form of Iron (as Ferrous Fumarate) is best?
tablet. Other forms in the catalog: capsule, liquid.
Is Iron (as Ferrous Fumarate) safe?
Commonly reported: constipation, nausea, abdominal discomfort, dark stools, vomiting.
Which Iron (as Ferrous Fumarate) supplement scores highest?
Thorne Iron Bisglycinate, at 96/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
18 mg / day · UL 45 mgIron (as Ferrous Fumarate) has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
Iron (as Ferrous Fumarate) dosage reference →Primary uses
- iron deficiency anemia treatment
- anemia prevention
- oxygen transport
- energy production
How it works
- component of hemoglobin for oxygen transport
- component of myoglobin for muscle oxygen storage
- cofactor in cytochrome P450 enzymes
- supports cellular energy production
Dosage
- Typical range
- 18-27 mg elemental iron daily (adult women); 8-11 mg daily (adult men)
- Timing
- take on empty stomach for optimal absorption, or with small amount of food if GI upset occurs
- With food
- preferably without food, but avoid dairy, calcium, and coffee which reduce absorption
- Duration
- treatment duration depends on deficiency severity; typically several months for repletion
- Special populations
- pregnant women: 27 mg daily; children require age-adjusted dosing; avoid in hereditary hemochromatosis
Forms
- tablet· 70/100
- capsule· 70/100
- liquid· 70/100
Safety
Common side effects
- constipation
- nausea
- abdominal discomfort
- dark stools
- vomiting
Contraindications
- hemochromatosis
- hemosiderosis
- repeated blood transfusions
- active GI bleeding
Products containing Iron (as Ferrous Fumarate)
Top-scoring supplements in our catalog that list Iron (as Ferrous Fumarate) on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Iron deficiency anemia treatment is supported by extensive clinical evidence; ferrous fumarate specifically has strong bioavailability data.
Grade A: Multiple well-designed human trials support the main claims.
Related in Mineral
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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.