There are many different forms of iron salts, and not all of them work the same way in the body. Each type has its own absorption rate, side effect profile, and role in treatment. Understanding the differences can help patients and practitioners choose the most suitable option for iron deficiency.
Ferrous gluconate
Ferrous gluconate is often well tolerated and contains a lower amount of elemental iron per tablet compared to other salts. This can make it gentler for individuals who experience stomach upset with stronger preparations. It is commonly used in people who have mild deficiency or those who prefer a softer introduction to iron therapy.
Ferrous sulfate
Ferrous sulfate is one of the most widely used forms worldwide. It is affordable, effective, and well studied. It provides a moderate amount of elemental iron and is typically recommended as a first line option. Some individuals may experience gastrointestinal symptoms such as nausea or constipation. These side effects often impact long term adherence, which is an important factor when rebuilding iron stores.
Ferrous fumarate
Ferrous fumarate contains a higher concentration of elemental iron than ferrous gluconate or ferrous sulfate. It is considered an effective option for raising iron stores. Some studies suggest it can still cause gastrointestinal discomfort, although this varies from person to person. Its higher elemental iron content can be helpful when stronger repletion is needed.
Iron bisglycinate
Iron bisglycinate is a chelated form of iron that tends to be gentler on the stomach. It is often chosen by individuals who have had trouble tolerating traditional salts. Research shows that iron bisglycinate has good absorption and may be easier to continue long term due to fewer digestive side effects. Its safety and tolerability make it a popular choice in prenatal care and general nutrient repletion.
Heme iron
Heme iron is sourced from animal products, especially liver and other organ meats. Supplemental forms of heme iron are absorbed efficiently because the body takes up heme through a pathway that is different from non heme forms. It is usually well tolerated and can be an option for those who need support but experience discomfort with typical ferrous salts. It tends to be more expensive and is not suitable for individuals who avoid animal based products.
Non heme iron
Non heme iron is found naturally in plant foods such as legumes, nuts, seeds, and leafy greens. It is less efficiently absorbed because it competes with other dietary components. In supplement form, non heme iron varies in absorption depending on the salt used. Pairing it with vitamin C rich foods can support better uptake.
Ferrous ascorbate
Ferrous ascorbate combines iron with vitamin C. Vitamin C can enhance absorption in the small intestine and may reduce the chance of constipation in some individuals. This combination is used in certain clinical settings where increased absorption is desired. While it shows good absorption, it is not always the first choice because availability and cost may differ compared to more common salts.
Polysaccharide iron complex
Polysaccharide iron complex is a non ionic form of iron that is designed to be gentler on the digestive system. It can be helpful for individuals who cannot tolerate traditional salts. However, studies suggest that its absorption can be lower than ferrous salts, which means it may take longer to restore iron stores. It is often used in mild to moderate deficiency or when other forms are not tolerated.
It is always important to speak with a healthcare professional when choosing an iron supplement. Each form has its own absorption rate, side effect profile, and ideal use, so what works well for one person may not be the best option for another. A clinician can review your blood work, medical history, current medications, and digestive tolerance to help determine the most suitable preparation. They can also guide you on the correct dose, how long to take it, and how to monitor your response. This approach helps ensure that treatment is safe, effective, and tailored to your needs.
About the author:
Hi, I’m Abinaa, a fourth-year naturopathic medical student at the Canadian College of Naturopathic Medicine with a deep-rooted passion for natural healing, inspired by my South Asian upbringing. Through this blog, I hope to share my journey, explore topics in holistic health and wellness, and offer simple, thoughtful insights that support a more balanced and mindful way of living.
