Does Iron Bisglycinate Have Elemental Iron?

October 31, 2025 •

3 min read

Approximately 2 billion people worldwide suffer from iron deficiency, making effective iron supplementation a critical health topic. Iron bisglycinate is a chelated form of iron that contains elemental iron, but its unique structure ensures better absorption and fewer gastrointestinal side effects than other iron compounds.

Quick Summary

Iron bisglycinate contains elemental iron, which is chelated or bound to two glycine molecules. This superior chelated structure enhances the bioavailability and absorption of the iron, minimizing side effects like constipation common with traditional iron salts.

Key Points

Contains Elemental Iron: Iron bisglycinate is a chelated compound that contains elemental iron, the active form the body needs.
Chelated Structure: The elemental iron is bound to two glycine molecules, creating a protective chelate structure.
Enhanced Absorption: The chelated form is recognized by the body, leading to better absorption and higher bioavailability than traditional iron salts.
Fewer Side Effects: The chelate protects the gut from free iron, resulting in significantly fewer gastrointestinal side effects like constipation and nausea.
Effective at Lower Doses: Due to its superior absorption, iron bisglycinate can be effective even at lower dosages of elemental iron compared to other forms.
Avoids Absorption Inhibitors: The stable chelate is less affected by common dietary inhibitors like phytates and tannins, ensuring consistent absorption.

Understanding Elemental Iron and Its Role

Elemental iron is the usable amount of iron in a supplement that the body can absorb. This is the key figure when addressing iron deficiency or anemia, and different iron compounds have varying percentages of elemental iron. For example, ferrous sulfate is about 20% elemental iron, and ferrous fumarate is roughly 33%. The form of the iron, like whether it is chelated, affects absorption.

The Unique Nature of Iron Bisglycinate

Iron bisglycinate is a chelated form where ferrous iron is bonded to two glycine molecules. This stable structure protects the iron in the digestive system, leading to several benefits over traditional iron salts like ferrous sulfate:

Enhanced Absorption: The glycine in iron bisglycinate aids iron uptake.
Superior Bioavailability: It is more bioavailable than ferrous sulfate, even with dietary inhibitors present.
Fewer Side Effects: Gastrointestinal issues common with other iron supplements are significantly reduced with iron bisglycinate.

How Iron Bisglycinate Delivers Elemental Iron

Iron bisglycinate largely stays intact until it reaches the small intestine. Instead of releasing free iron ions, which can cause irritation, the body absorbs the chelated molecule through a process similar to amino acid absorption. Once inside intestinal cells, the elemental iron is released and joins the body's iron supply, with absorption regulated by the body's needs. This mechanism makes iron bisglycinate more efficient than iron salts for delivering elemental iron.

List of Absorption Benefits

High absorption rates: More iron is absorbed into the bloodstream.
Gentle on the stomach: The chelated form minimizes irritation.
Avoids absorption inhibitors: The stable chelate is protected from dietary factors like phytates and tannins.
Higher efficacy at lower doses: Better bioavailability means lower doses can be effective.

Comparison of Iron Supplements

Comparing iron bisglycinate to other supplements highlights its advantages. While elemental iron content is important, absorption and side effects are key to effectiveness and patient adherence.


Feature	Iron Bisglycinate	Ferrous Sulfate	Ferrous Fumarate
Structure	Chelated (iron bound to glycine)	Inorganic iron salt	Inorganic iron salt
Bioavailability	High; well-absorbed	Low; poorly absorbed in GI tract	Moderate; better than sulfate but less than bisglycinate
Elemental Iron Content	Lower percentage by weight, but higher absorption makes it effective	Higher percentage by weight, but poorly absorbed	Higher percentage by weight, but less absorbed than bisglycinate
Gastrointestinal Side Effects	Low incidence (e.g., less constipation)	High incidence (constipation, nausea, upset stomach)	Moderate incidence
Interaction with Food	Less affected by dietary inhibitors	Easily inhibited by phytates and other compounds	Can be affected by dietary inhibitors
Patient Compliance	High, due to fewer side effects	Low, due to unpleasant side effects	Variable

Conclusion

Yes, iron bisglycinate does contain elemental iron, but its chelated form provides a superior delivery method. Binding elemental iron to glycine enhances absorption and significantly reduces common side effects of traditional iron salts, leading to improved tolerability and effectiveness for addressing iron deficiency. It's always best to consult a healthcare professional to determine if iron bisglycinate is the right choice and dosage for your needs.

Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial.

Frequently Asked Questions

Elemental iron is the pure, active iron available for absorption. Iron bisglycinate is a compound where elemental iron is bound, or chelated, to two glycine molecules. This binding mechanism makes the elemental iron more bioavailable and gentler on the stomach.

Yes, elemental iron from bisglycinate is absorbed differently. Unlike iron salts which can release free iron ions that irritate the gut, the body absorbs the intact bisglycinate chelate directly. This specific pathway increases absorption efficiency and minimizes side effects.

Iron bisglycinate is gentle on the stomach because its chelated structure prevents the elemental iron from irritating the gastrointestinal lining. This reduces the likelihood of side effects such as nausea, constipation, and stomach cramps commonly associated with other iron supplements.

No, a higher percentage of elemental iron does not always guarantee a better supplement. While ferrous sulfate contains a higher percentage of elemental iron by weight, its absorption is often poor and inconsistent. The high bioavailability of iron bisglycinate often makes it more effective, even with a lower elemental iron dose.

Iron bisglycinate is less susceptible to dietary inhibitors than iron salts. Its chelated structure protects it from substances like phytates in cereals and tannins in tea and coffee, which can significantly hinder the absorption of other iron forms.

Yes, studies suggest that iron bisglycinate is safe for long-term use, especially since its absorption is regulated by the body's iron stores. Its superior tolerability also promotes better adherence to long-term supplementation regimens needed to replenish iron stores.

For optimal absorption, some sources recommend taking iron bisglycinate on an empty stomach with vitamin C. However, if you have a sensitive stomach, taking it with a light meal is often recommended, as its chelated form makes it highly tolerable even when taken with food.