By Noah Koster
2025 UBC PharmD Candidate
Choosing an iron supplement can be a challenge. Between the pharmacy and the internet, there are dozens of options, making it a nearly impossible task to know which is best and which one will be right for you. To make things even more complicated, many people don’t need iron supplements at all. So how do you choose? In this article, we will take you through the options and make your decision-making process a little easier.
Who needs iron?
Anemia occurs when red blood cells cannot transport enough oxygen throughout the body to meet its needs. Some of the most common symptoms of anemia include pale skin, fatigue, spooning nails, shortness of breath upon exertion, hair loss, irritability, and depression. While anemia may be due to low iron levels, it can also have other causes like a deficiency of vitamin B12 or folate, so not all types of anemia will be treated with iron supplements. For this article, we’ll focus on iron deficiency anemia (IDA).
To check for anemia, your doctor may order a blood test to examine lab values such as ferritin, hematocrit, and hemoglobin. Ferritin levels indicate how much iron is being stored, hematocrit (Hct) gives the percentage of red blood cells in the total blood volume, and hemoglobin (Hb) is a measure of the heme protein in red blood cells (heme carries oxygen). Ferritin is often the marker of choice for diagnosing IDA, as it’s a clear indicator of low iron levels.
In adults, ferritin under 15 mcg/L confirms IDA while 15-30 mcg/L means that IDA is likely. In men, Hb under 130 g/L or Hct less than 41% are indicative of IDA, while in non-pregnant women those values are Hb under 120 g/L or Hct under 36%. Depending on your levels, your doctor may recommend a lower dose iron supplement (30 to 75 mg) to prevent levels from falling further or a higher dose supplement (around 100 to 200 mg) to bring levels back into the normal range over 3 months, or sometimes longer.
Which type of iron supplement is the best?
There really is no specific iron supplement that is better than another. In fact, the best choice for you will depend on your needs. Are you using it for prevention or treatment? What dose do you need? Do you prefer a liquid or a tablet form? Do you already suffer from constipation or diarrhea? Is cost a concern? Let’s take a look at some of the available iron supplements and their advantages and disadvantages.
Iron Salts (Palafer)
The iron salts — ferrous gluconate, ferrous sulphate, and ferrous fumarate — are the cornerstone of iron replacement therapy. They are tried, tested, and known to work very well in restoring iron levels; in fact, they are typically the benchmark to which any new iron supplements are compared. The downside with iron salts is that they tend to upset people’s stomachs, causing nausea, diarrhea, or constipation, but these side effects can be lessened by starting with a low dose that is slowly increased or by taking every other day. These supplements are usually found as generic 300 mg tablets, but this is not the amount of elemental iron in each one; rather, ferrous gluconate has 35 mg of iron per tablet, ferrous sulphate contains 60 mg, and ferrous fumarate has 100 mg.
Polysaccharide Iron Complex (FeraMax, Polyride-Fe)
Polysaccharide iron complexes are tasteless and may cause fewer side effects than iron salts. However, they are more expensive than iron salts and won’t raise the body’s iron stores as quickly as other supplements, so treating anemia with these will likely be a longer process.
Heme Iron Polypeptide (Proferrin)
Unlike the other supplements, heme iron polypeptide is derived from animal sources. As a result, it tends to be more easily absorbed and have fewer side effects. These supplements are not typically used to treat anemia; instead, heme iron is used to prevent anemia in at-risk patients. Heme iron supplements are more expensive than other options.
Iron Amino Acid Chelates
Ferrous bisglycinate, ferrous bisglycine, ferrous trisglycine, and ferric glycinate are commonly used to fortify foods, but they can also be found as supplements. Iron amino acid chelates likely work as well, if not better, than iron salts for the treatment of anemia, and many people find they have fewer digestive side effects than with other alternatives. Ferrous bisglycinate is the most common of these supplements (usually 20 mg or 30 mg capsules) and can be found in some pharmacies, but it is most easily obtained from online sources.
Gentle Iron (Ferapro, Webber Naturals’ Gentle Iron, Nature’s Bounty Gentle Iron)
Gentle iron products are designed to cause fewer digestive side effects than other iron supplements. They typically contain iron (often an iron salt or iron bisglycinate) with vitamin C (which may help your body absorb iron), as well as vitamin B12 and folic acid (each of which plays a role in treating certain kinds of anemia). These products are expected to effectively treat anemia, and some people may experience fewer side effects than with other options. These supplements vary in price range, but they are more expensive than iron salts.
Liposomal Iron (Ferrosom)
Liposomal iron comes as either capsules or powders and is created to cause fewer side effects and be more easily absorbed. It is among the newer alternatives for iron supplements, and while it appears to be effective in treating anemia, there are few head-to-head comparisons with other more treatment options, so it is a challenge to judge how well it works.
Which iron supplement should you choose?
Iron supplementation can be tricky. Appropriate doses will vary depending on your hemoglobin levels, and iron supplements interact with many common medications (e.g., antacids, antibiotics, thyroid hormones, alendronate). And there are additional treatment considerations if you have other medical conditions. After having lab tests for anemia, sit down with our pharmacists for a medication review. We can review your results and work with you to choose the iron supplement that will be best for you.