Iron Supplements

Monday June 1 2015

Iron Supplements

Tara Loseth, R.Ph. May 2015

If you have had a blood test and are low in iron, your doctor  has likely recommended that you take an iron supplement.  But which one should you take?  There are many iron supplements available, and they differ in price, iron content, type of iron, and tolerability. This article will clarify your choices, and will help you to decide which iron supplement is right for you.

Iron salts

These include Ferrous Gluconate, Ferrous Sulfate, and Ferrous Fumarate.

Ferrous Gluconate 300mg tablets contain 35mg of iron

Ferrous Sulfate 300mg tablets contain 60mg of iron (also comes in liquid and infant drops)

Ferrous Fumarate 300mg tablets or capsules contain 100mg of iron

These three iron salts have been around a long time and are the least expensive iron supplements.  They are best absorbed on an empty stomach with water, or with an acidic drink such as orange juice.  Taking a Vitamin C tablet along with water also improves absorption.

Iron salts are much less expensive than other options, and they are effective if taken correctly.  But some people experience side effects such as nausea and stomach pain.  To reduce these side effects you can take them with food; however, this will lower the absorption of iron.  Iron salts can also cause constipation; this can be made worse if you take them with food, since the iron will bind to the food.

Iron complexes

Iron polysaccharide (including FeraMaxR and other brands) – iron is attached to and surrounded by starch, making it tasteless and odourless.  This product contains 150mg of elemental iron.  Iron polysaccharides have been shown to raise iron levels.  However, unlike the other options, no information is available on how much iron gets absorbed per dose.

FeramaxR comes as a gelatin capsule or as a powder.

Iron-heme complex (ProferrinR) – iron is attached to and surrounded by a protein, making it easy for the small intestine to absorb.  Although this product contains less iron than the other products, more iron gets absorbed from each dose than from any of the iron salts.

Iron complexes cause less nausea and bowel side effects than iron salts, and they can be taken with or without food.  However, it should be noted that they are not as well-studied as the older iron salts.  There are no studies to compare the effectiveness of the old iron salts to the new iron complexes.


Make sure your iron supplement is spaced apart from any medications that you take *

Keep iron supplements out of reach of children - overdose is harmful *


Vegan/Vegetarian options

For those wishing to avoid animal products, the choices are either the iron salts or FeraMaxR powder.  FeraMaxR capsules contain animal gelatin, and the ProferrinR protein is from a bovine source.

Other iron-containing products


These usually contain a small amount of iron, in the form of iron salts (4mg-10mg, up to 27mg in prenatal multivitamins)  Because the iron is included with other minerals, iron absorption is less.

Slow-release iron:

These are expected to have less absorption than regular-release products

Ferric ammonium citrate (Iron CitrateR), Carbonyl Iron, Ferrous Bisglycinate:

These are iron products that are not readily available in Canada.

Iron injections:

If a person cannot tolerate oral iron, or cannot absorb oral iron, they may need to take an                 injectible form.

Iron-containing foods

Dietary iron - especially foods such as liver, lean red meats, seafood such as oysters, clams, tuna, salmon, sardines and shrimp - will help to raise your iron levels.  However, they typically take more time to raise iron levels than iron supplements do.  Something else to keep in mind is that drinking tea or coffee can lower the amount of iron you absorb from your food.

More information

HealthLinkBC-What Foods Have Iron

HealthLinkBC-Iron and Your Health

HealthLink BC - Iron Deficiency Anemia

The Iron Maiden  -> this is an excellent website to help you learn more about iron deficiency and treatments, but bear in mind that the author is sponsored by an iron supplement company.


Iron supplements can be found behind the pharmacy counter. 

Your local pharmacist will be happy to help you select one, and to answer any questions you may have about iron supplementation.



 -  Detail-Document #240811 from PHARMACIST’S LETTER / PRESCRIBER’S LETTER August 2008 ~ Volume 24 ~ Number 240811

-  Am J Clin Nutr. 2001 Nov;74(5):650-6. Dietary treatment of iron deficiency in women of childbearing age. Patterson AJ1, Brown WJ, Roberts DC,   Seldon MR.

-  Am J Clin Nutr. 1990 Apr;51(4):649-55.  Ascorbic acid: effect on ongoing iron absorption and status in iron-depleted young women.  Hunt JR1, Mullen - LM, Lykken GI, Gallagher SK, Nielsen FH.

-  Crit Rev Food Sci Nutr. 2000 Sep;40(5):371-98.  Effect of tea and other dietary factors on iron absorption.  Zijp IM1, Korver O, Tijburg LB.

-  Am Fam Physician. 2013 Jan 15;87(2):98-104.  Iron deficiency anemia: evaluation and management.  Short MW1, Domagalski JE.

-  Compendium of Pharmaceuticals and Specialties, online version (e-CPS).   CPhA Monograph:  Iron Preparations: Oral  November 2011

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