Types of Iron Supplements
In this guide, we’ll help you understand the types of iron supplements and what to look for in an iron vitamin.
By Halle Tecco, MBA, MPH
Iron is a micronutrient vital to disease prevention, health, and wellbeing. Although iron is found naturally in many foods, it is difficult for your body to absorb, especially during pregnancy. Without enough iron, your body cannot make hemoglobin, and you may develop anemia. Anemia is the most common blood disorder, and according to the National Heart, Lung, and Blood Institute, it affects more than three million Americans.
According to the Centers for Disease Control and Prevention (CDC)1:
- Iron is critical for motor and cognitive development. Children and pregnant women are especially vulnerable to the consequences of iron deficiency.
- Iron is a leading cause of anemia which is defined as low hemoglobin concentration. Anemia affects 43% of children younger than five years of age and 38% of pregnant women globally.
- Anemia during pregnancy increases the risk of death for the mother and low birth weight for the infant. Worldwide, maternal and neonatal deaths total between 2.5 million and 3.4 million each year.
- The World Health Organization (WHO) recommends iron and folic acid supplements for reducing anemia and improving iron status among women of reproductive age.
One way doctors treat iron deficiency and anemia is through oral iron supplements, intended to increase the levels of iron and hemoglobin in your body. But with so many options on the market, how do you know which type of iron supplement is best for you? Let's delve into the world of iron supplementation.
Different Types of Iron Supplements
Ferrous sulfate is one of the most common forms of iron supplements as it contains a high concentration of elemental iron, making it an effective option for treating iron deficiency.2 It is readily absorbed by the body and is often recommended for individuals experiencing a low iron level.
Ferrous gluconate is another widely used iron supplement and is known for its gentle effect on the stomach, making it a suitable choice for those with sensitive digestive systems. While ferrous gluconate contains less elemental iron compared to ferrous sulfate, its absorption rate is still satisfactory.3
This form of iron supplement contains a higher concentration of elemental iron than ferrous gluconate.4 It is well-absorbed and is often used to treat iron deficiency anemia. It is advisable to take ferrous fumarate with vitamin C-rich foods to enhance iron absorption.
Chelated Iron Supplements
Chelated iron supplements consist of iron molecules bound to amino acids, enhancing their absorption in the body. This form of oral iron supplementation is gentle on the stomach and is less likely to cause digestive discomfort.5
Liquid Iron Supplements
These types of iron supplements offer a convenient and easy-to-digest alternative to traditional tablets or capsules. They are absorbed quickly by the body and are a suitable choice for individuals who have difficulty swallowing pills. Liquid iron supplements often come in various flavors and can be taken on their own or mixed with juice or water. However, they may not provide as high a concentration of iron as other forms.6
Look at the “Supplement Facts”
High purity iron is the form of iron best used by your body. Often, two iron amounts are listed on a supplement label: the larger number being the chemical compound form and the smaller number being the amount of iron in the compound (aka the high purity iron). When choosing a supplement, look at the type of iron in the formula. For instance,
- Carbonyl has 98-100% high purity iron
- Ferrous fumarate has approximately 33% high purity iron
- Ferrous sulfate has 20% high purity iron
- Ferrous gluconate has 12% high purity iron
Read the label closely . For example, 54 mg of carbonyl contains 54 mg of high purity iron, but 54 mg of ferrous sulfate contains only 10.8 mg of high purity iron.
Look for Carbonyl iron
Not only does Carbonyl iron contain the most high purity iron, it is often preferred by physicians because it is less toxic to children who might take an accidental overdose. Carbonyl iron is significantly less toxic than the other options due to the fact that it must first be solubilized by gastric acid.7
One research paper called Carbonyl iron “an effective, inexpensive treatment for iron deficiency anemia” because it is “accompanied by tolerable side effects and may have an advantage over therapy with iron salts by substantially reducing or eliminating the risk of iron poisoning in children.”8
Decide if you prefer a tablet or liquid
Iron supplements generally come in liquid, tablet, or capsule form. We haven’t found a manufacturer that makes iron gummies, probably due to the unpleasant taste of iron alone (or the fact that gummies look like candy to children). Gummy multivitamins are also more likely to fail ConsumerLab's tests of quality than tablets, as they often contain much less or much more of the listed amounts of ingredients.9
If you have difficulty swallowing pills, then liquid may be a good alternative. However, liquid is often harder on the stomach, so there’s a tradeoff. The Natalist Iron supplement is a small tablet, which has low toxicity and is easy on the stomach.
Choose a brand that is GMP certified
GMP (which stands for 'Good Manufacturing Practices') is a set of best practices for dietary supplement manufacturing in the United States that are maintained by the FDA. These regulations establish the baseline quality requirements for dietary supplement companies and manufacturers. In addition to ensuring quality control and assurance, GMP’s requirements help ensure that dietary supplement products consistently meet specifications for purity, strength, and composition. Manufacturers get GMP certified through an audit by a third-party organization like NSF. If you don’t see GMP or NSF certification, R-U-N.
All Natalist vitamins are made in an NSF-certified facility, which exceeds the FDA cGMP (Good Manufacturing Practices) manufacturing standards. Certificates of analysis are reported for every batch of manufactured vitamin to ensure final product integrity and quality.
Ask your physician for the right dosage
Too much iron can be toxic to the liver and cause serious health problems. The best way to determine your optimal dose is to talk to your doctor and take an iron supplement as instructed. For pregnant women, the CDC recommends treating anemia through an oral dose of 60 to 120 mg per day of iron.10 Always check with your physician before starting an iron supplement, and be sure to get a specific recommendation for the type of iron and dosage.
Learn more about proper nutrition for fertility and pregnancy.
- Centers for Disease Control and Prevention. Micronutrient Facts . Centers for Disease Control and Prevention. Published April 30, 2018. https://www.cdc.gov/nutrition/micronutrient-malnutrition/micronutrients/index.html
- Cleveland Clinic. Iron Supplements for Anemia (Ferrous Sulfate): Types, Benefits & Side Effects. Cleveland Clinic. Published May 24, 2022. https://my.clevelandclinic.org/health/drugs/14568-iron-oral-supplements-for-anemia
- Harvard School of Public Health. Iron. Harvard School of Public Health. Published September 16, 2019. https://www.hsph.harvard.edu/nutritionsource/iron/
- National Institutes of Health. Office of Dietary Supplements - Iron. Nih.gov. Published April 5, 2022. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional
- Mayo Clinic. Iron Supplement (Oral Route, Parenteral Route) Description and Brand Names - Mayo Clinic. Mayoclinic.org. Published 2019. https://www.mayoclinic.org/drugs-supplements/iron-supplement-oral-route-parenteral-route/description/drg-20070148
- Society for the Advancement of Blood Management. Patient’s Guide to Oral Iron | Iron Corner | SABM. Society for the Advancement of Blood Management. Published December 23, 2020. https://sabm.org/patient-guide-to-oral-iron/
- Mudan A, Lebin J. Iron Toxicity - Emergency Management - DynaMed. DynaMed. Published 2023. https://www.dynamed.com/management/iron-toxicity-emergency-management
- Gordeuk VR, Brittenham GM, McLaren CE, Hughes MA, Keating LJ. Carbonyl iron therapy for iron deficiency anemia. Blood. 1986;67(3):745-752. https://www.ncbi.nlm.nih.gov/pubmed/3947745
- Cooperman T. Iron in Multivitamins & Gummies. ConsumerLab.com. Published Autumn 6, 2018. https://www.consumerlab.com/answers/why-is-iron-not-in-many-multivitamins-how-can-i-find-one-that-does-contain-iron/iron-in-multivitamins/
- Morey S. CDC Issues Guidelines for Prevention, Detection and Treatment of Iron Deficiency. American Family Physician. 2013;58(6):1475. https://www.aafp.org/afp/1998/1015/p1475.html