Iron Bisglycinate Explained – Everything You Need to Know About Chelated Iron

When it comes to iron supplements, form really does matter. On one hand there’s ferrous sulphate, fumarate, and gluconate, and on the other hand, iron bisglycinate. So why do we prefer iron bisglycinate, and what advantages does it offer over the others? Time for some mineral chemistry and to share everything you need to know about chelated iron.

What is iron bisglycinate?

Iron bisglycinate is a chelated form of iron, made from iron bound to two molecules of the amino acid glycine. 

Minerals need to be bonded to a carrier substance so we can ingest them as supplements. Glycine is a good choice as a carrier molecule because your body recognises it easily and absorbs the attached iron. 

Iron bisglycinate has been shown to have higher bioavailability and absorption compared to iron salts like ferrous sulphate and ferrous fumarate and is less likely to leave you with a metallic taste or cause bloating, nausea, or constipation [1].

What does iron do?

Iron plays a central role in energy production, immunity, detoxification, and cognitive health:

Energy production: iron is used by enzymes and electron transport chains in mitochondrial energy production [2]. Iron deficiency impairs energy metabolism, causing fatigue and tiredness.

Oxygen transport: iron is used to build haemoglobin, a protein in red blood cells that carries oxygen around the body, and myoglobin, an oxygen-binding protein in muscle tissue [3].

Immune health: immune cells depend on iron for normal growth, differentiation, and activity [4]. 

Detoxification: the cytochrome P450 family of enzymes that metabolise various drugs, hormones, and toxins in the liver depend on iron availability to function properly.

Cognitive health: iron influences the synthesis and signaling of neurotransmitters such as dopamine, noradrenaline, and adrenaline. It’s also needed for healthy nerve myelination and energy metabolism in the brain [5].

Normal cell division: iron-dependent enzymes play an essential role in cell metabolism and DNA synthesis.

What are the symptoms of iron deficiency?

A short-term fall in iron levels doesn’t always cause any obvious symptoms because your body uses up the iron stores in your liver, muscles, spleen, and bone marrow. Long term iron deficiency can lead to iron-deficiency anaemia. Commons signs include [6]:

• Fatigue and low energy

• Breathlessness

• Headaches

• Looking pale

• Heart palpitations

More unusual symptoms may include [6]:

• Tinnitus

• Hair loss

• A sore tongue and ulcers at the corner of the mouth

• A craving to eat non-food items like paper or coal

• Sunken nails that look like a spoon

What are the benefits of iron bisglycinate?

The advantage of iron bisglycinate is that it’s gentle on your digestion, non-constipating, and very well absorbed compared to other forms of iron. 

This makes it a good choice for people who are:

• Pregnant and/or breastfeeding. 

• Vegan or vegetarian and/or have a diet that’s low in iron. Plant sources of iron (called non-haem iron) are not as bioavailable as the haem iron found in animal products. 

• Managing iron deficiency anaemia.

• Managing heavy periods or a health condition like ulcerative colitis that may cause frequent blood loss.

• Taking medication that impairs iron absorption.

What’s the difference between iron bisglycinate and ferrous sulphate?

*Researchers examining the prevention of iron deficiency in pregnancy found that 25mg of iron bisglycinate was as effective as 50mg ferrous sulphate in preventing iron deficiency and caused far fewer side effects [7].

Does iron bisglycinate cause constipation?

Iron bisglycinate is known as a gentle, non-constipating form of iron. It’s a good choice during pregnancy and for those with a sensitive digestion because it’s so well tolerated and less likely to cause constipation compared to ferrous sulphate or fumarate [1].

How much iron should I take?

The amount of iron you need from a supplement depends on your age, sex, and current dietary intake. 

Our Iron Bisglycinate provides 20mg of elemental iron, a clinically relevant dose to support energy levels, normal immune function, and cognitive health. 

How can I improve my iron absorption?

Once you’ve bought your iron supplement, you want to get the most from it so try these tips for maximising iron absorption.

It’s a good idea to take your iron with either a glass of water or natural fruit juice (the vitamin C in fruit enhances iron absorption). Don’t take it with black, green, or white tea, as tea contains tannins that can interfere with iron uptake. 

Other potential absorption inhibitors include dairy products and foods rich in phytates, such as beans, pulses, and wholegrains [8]. Enjoy these foods a couple of hours before or after taking your iron supplement.

FAQs

What is iron bisglycinate?

Iron bisglycinate is a chelated form of iron made from iron bound to two molecules of the amino acid glycine. It is gentle on the stomach, non-constipating, and well tolerated during pregnancy and by people with a sensitive digestion. 

What are the benefits of iron bisglycinate?

Iron bisglycinate is a highly bioavailable form of iron that can be used to support normal iron levels. Iron plays a central role in energy metabolism, normal immune function, oxygen transport, detoxification, and cognitive health.

What symptoms can iron deficiency cause?

Common symptoms of iron deficiency are fatigue and tiredness, breathlessness, pale skin, headaches, and heart palpitations.

What is the difference between iron bisglycinate and ferrous sulfate?

Ferrous sulphate is a type of iron salt whereas iron bisglycinate is a chelated form of iron. Iron bisglycinate is better absorbed and less likely to cause constipation, nausea, and gastrointestinal discomfort compared to ferrous sulphate. 

Is iron bisglycinate chelated?

Yes, iron bisglycinate is a chelated form of iron made from elemental iron bound to glycine.

We hope this has explained the many advantages of iron bisglycinate over other forms of iron. We think it’s the superior choice and hope you do too!

If you have any questions about Iron Bisglycinate or any of our other mineral products, do get in touch. Discover our full range of chelated minerals and shop for Iron Bisglycinate in our online store today.

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References

1. Bumrungpert, A., Pavadhgul, P., Piromsawasdi, T., & Mozafari, M. R. 2022. Efficacy and Safety of Ferrous Bisglycinate and Folinic Acid in the Control of Iron Deficiency in Pregnant Women: A Randomized, Controlled Trial. Nutrients, 14(3), 452. https://doi.org/10.3390/nu14030452 

2. Kim, S. L., Shin, S., & Yang, S. J. 2022. Iron Homeostasis and Energy Metabolism in Obesity. Clinical Nutrition Research, 11(4), 316–330. https://doi.org/10.7762/cnr.2022.11.4.316 

3. National Institutes of Health, 2023. Iron. [online] Available at https://ods.od.nih.gov/factsheets/Iron-Consumer/ [Accessed 11 Aug 2025].

4. Haschka, D., Hoffmann, A., & Weiss, G. 2021. Iron in immune cell function and host defense. Seminars in Cell & Developmental Biology, 115, 27-36. https://doi.org/10.1016/j.semcdb.2020.12.005 

5. Hare, D. J., Ayton, S., Bush, A. I., & Lei, P. 2013. A delicate balance: Iron metabolism and diseases of the brain. Frontiers in Aging Neuroscience, 5, 54825. https://doi.org/10.3389/fnagi.2013.00034 

6. NHS, 2024. Iron deficiency anaemia. [online] Available at https://www.nhs.uk/conditions/iron-deficiency-anaemia/ [Accessed 11 Aug 2025].

7. Milman, N., Jønsson, L., Dyre, P., Pedersen, P.L., Larsen, L.G. 2014. 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. Journal of Perinatal Medicine 42(2):197-206. doi: 10.1515/jpm-2013-0153. PMID: 24152889 

8. Petroski, W., & Minich, D. M. 2020. Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds. Nutrients, 12(10), 2929. https://doi.org/10.3390/nu12102929