Mineral
Iron (Ferrous Sulfate)
Also known as: ferrous sulfate, FeSO4, iron(II) sulfate, fe
An essential mineral critical for oxygen transport, energy production, and immune function. Ferrous sulfate is a highly bioavailable form commonly used in supplemental iron products.
Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.
Every Iron (Ferrous Sulfate) 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 (Ferrous Sulfate) should I take?
The typical range is 8-18 mg daily (recommended dietary allowance); 25-325 mg daily for anemia treatment. Supplement duration depends on severity of deficiency; treatment typically 3-6 months; maintenance dose for prevention
When should I take Iron (Ferrous Sulfate)?
Take on empty stomach 1 hour before or 2 hours after meals for optimal absorption; with food if GI upset occurs. Food reduces absorption by ~40-50%; vitamin C enhances absorption; avoid calcium, tea, coffee which inhibit absorption.
Which form of Iron (Ferrous Sulfate) is best?
ferrous sulfate. Other forms in the catalog: ferrous bisglycinate, ferrous fumarate, ferric citrate.
Is Iron (Ferrous Sulfate) safe?
Commonly reported: Nausea (very common), Constipation or diarrhea, Abdominal discomfort, Dark-colored stools (expected, not harmful), Headache, Metallic taste.
Which Iron (Ferrous Sulfate) 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 (Ferrous Sulfate) has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
Iron (Ferrous Sulfate) dosage reference →Primary uses
- Oxygen transport (hemoglobin synthesis)
- Energy production
- Immune function
- Cognitive development and function
- Iron deficiency anemia prevention and treatment
How it works
- Core component of hemoglobin and myoglobin
- Cofactor for cytochrome oxidase and other enzymes
- Essential for ATP synthesis
- Required for immune cell function
Dosage
- Typical range
- 8-18 mg daily (recommended dietary allowance); 25-325 mg daily for anemia treatment
- Timing
- Take on empty stomach 1 hour before or 2 hours after meals for optimal absorption; with food if GI upset occurs
- With food
- Food reduces absorption by ~40-50%; vitamin C enhances absorption; avoid calcium, tea, coffee which inhibit absorption
- Duration
- Supplement duration depends on severity of deficiency; treatment typically 3-6 months; maintenance dose for prevention
- Special populations
- Women 19-50 require 18 mg daily; postmenopausal women and men require 8 mg daily; pregnant women require 27 mg daily; children require 7-11 mg daily based on age
Forms
- ferrous sulfate· 70/100
- ferrous bisglycinate· 70/100
- ferrous fumarate· 70/100
- ferric citrate· 70/100
Safety
Common side effects
- Nausea (very common)
- Constipation or diarrhea
- Abdominal discomfort
- Dark-colored stools (expected, not harmful)
- Headache
- Metallic taste
Contraindications
- Hemochromatosis or iron overload disorders
- Certain anemias (sideroblastic, hemolytic)
- Active gastrointestinal bleeding without investigation
- Frequent blood transfusions
Products containing Iron (Ferrous Sulfate)
Top-scoring supplements in our catalog that list Iron (Ferrous Sulfate) on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.
Evidence notes
Extensive RCT evidence for iron deficiency anemia treatment and prevention. Strong evidence for efficacy of ferrous salts. Well-established hematologic and biochemical benefits.
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.