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Ferrous Sulfate vs. Iron Glycinate: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on January 11, 2024
Ferrous sulfate is a common iron supplement used to treat anemia; iron glycinate is a gentler, highly bioavailable form of iron supplement.

Key Differences

Ferrous sulfate is an iron salt, a combination of iron and sulfuric acid. Iron glycinate, also known as ferrous bisglycinate, is iron chelated with glycine, making it more absorbable.
Ferrous sulfate is effective but can be harsh on the stomach and may cause gastrointestinal side effects. Iron glycinate offers higher bioavailability and is gentler on the digestive system, reducing the likelihood of side effects.
Both are used to treat iron deficiency and anemia. Ferrous sulfate is often the first choice due to its effectiveness and lower cost. Iron glycinate is preferred when patients experience side effects from other iron supplements.
Ferrous sulfate may require higher doses to achieve desired iron levels but can lead to constipation or stomach upset. Iron glycinate can be taken in lower doses due to its higher absorption rate, minimizing gastrointestinal issues.
Ferrous sulfate is widely prescribed but may not be suitable for everyone due to its side effects. Iron glycinate is often recommended for those who have difficulty tolerating other iron supplements, including pregnant women and individuals with sensitive stomachs.

Comparison Chart

Chemical Form

Iron salt (iron and sulfuric acid)
Iron chelated with glycine

Bioavailability and Absorption

Lower bioavailability, harsher on stomach
Higher bioavailability, gentler on the digestive system

Common Use

First-line treatment for anemia
Used when patients have side effects from other iron forms

Side Effects

May cause gastrointestinal issues
Fewer gastrointestinal side effects

Dosage and Administration

Often requires higher doses
Effective at lower doses

Ferrous Sulfate and Iron Glycinate Definitions

Ferrous Sulfate

Gastrointestinal Effects.
Some people experience stomach upset from ferrous sulfate.

Iron Glycinate

Highly Absorbable Iron.
Iron glycinate is preferred for its high bioavailability.

Ferrous Sulfate

Anemia Treatment.
Doctors often prescribe ferrous sulfate for iron-deficiency anemia.

Iron Glycinate

Chelated Iron Form.
Iron glycinate is iron chelated with glycine for better absorption.

Ferrous Sulfate

Common Iron Form.
Ferrous sulfate is a widely used iron supplement.

Iron Glycinate

Gentle Iron Supplement.
Iron glycinate is recommended for its gentle effect on the stomach.

Ferrous Sulfate

Iron Supplement.
Ferrous sulfate supplements are used to treat anemia.

Iron Glycinate

Suitable for Sensitive Stomachs.
For those with stomach issues, iron glycinate is often advised.

Ferrous Sulfate

Iron Salt Form.
Ferrous sulfate is a form of iron combined with sulfuric acid.

Iron Glycinate

Effective at Lower Doses.
Iron glycinate can be taken in lower doses due to its efficiency.


Why is ferrous sulfate commonly prescribed?

For its effectiveness in treating iron deficiency anemia.

Can ferrous sulfate cause side effects?

Yes, it can cause gastrointestinal issues like constipation or stomach upset.

What is ferrous sulfate?

A common iron supplement used to treat iron deficiency.

Why might someone prefer iron glycinate?

Due to its higher bioavailability and fewer gastrointestinal side effects.

Is iron glycinate more expensive than ferrous sulfate?

Generally, iron glycinate is more expensive.

What makes iron glycinate different in terms of absorption?

It's chelated, making it easier for the body to absorb without causing discomfort.

Can ferrous sulfate interact with other medications?

Yes, it can interact with certain medications and should be taken under guidance.

What is iron glycinate?

A form of iron supplement that is gentler on the stomach.

Is iron glycinate safe for pregnant women?

Yes, it's often recommended due to its gentler nature.

Can children take ferrous sulfate?

Yes, but under medical supervision and appropriate dosing.

How does the body absorb ferrous sulfate?

It's absorbed in the gut but can be harsh on the stomach.

Does ferrous sulfate affect stool color?

It can darken the stool, which is normal when taking iron supplements.

Can either supplement cause allergic reactions?

While rare, allergic reactions can occur with any supplement.

Is iron glycinate suitable for vegans?

Yes, it's also free from animal-derived ingredients.

Is ferrous sulfate vegan?

Yes, it does not contain animal-derived ingredients.

How is iron glycinate taken?

Usually in capsule or tablet form, as directed by a healthcare provider.

Can either supplement cure anemia permanently?

They treat anemia caused by iron deficiency but may not cure underlying causes.

Is iron glycinate a good option for long-term use?

Yes, especially for individuals who need ongoing iron supplementation.

How quickly do ferrous sulfate supplements work?

Improvement in symptoms can be seen in a few weeks.

Does iron glycinate have any impact on stool?

Less likely than ferrous sulfate, due to its gentler nature.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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