Converting Between Ferrochel and Ferrous Sulfate
In our latest question and answer, the pharmacist compares Ferrochel (iron bisglyinate) and ferrous sulfate as well as discusses conversions between them.
We have been asked by our doctor to give 40 mg iron to our 3-year-old son with an iron deficiency. We would like to use a product called Nature's Nutra with iron from Ferrochel Ferrous bisglycinate Chelate so it is easier on his stomach and has fewer side effects. In the research we have done it sounds like we need to give less of this type of iron than needed for Ferosul Elixir (220mg 44mg iron) for equal effects. Nature's Nutra with iron from Ferrochel Ferrous Bisglycinate Chelate is 5mg per 1ml dropper. It doesn't say how much elemental iron is in the product. If it is 5mg, we were wondering if giving 4ml (20mg) of this product would be equal to the 40mg iron the doctor wants us to give based on its better absorption and potency. Thank you!
Over the counter iron supplements are commonly used to prevent iron deficiency as well as treat a variety of iron-related conditions, like anemia.
Unfortunately, picking the right iron supplement, or even using the right dose, can be extremely challenging. There are no less than six different iron forms on the market, including:
- Ferrous sulfate
- Ferrous gluconate
- Ferrous fumarate
- Carbonyl polypeptide
- Iron citrate
- Ferrous bisglycinate (Ferrochel)
If the sheer variety of iron products wasn't enough, each contains a differing amount of elemental iron. This point can be extremely confusing, and it is essential to understand the elemental iron content in a particular product.
Let's take ferrous sulfate for example. Ferrous sulfate, written in the molecular form, is FeSO4. It is comprised of both iron and a 'sulfate' group. Ferrous sulfate products contain only 20% elemental iron by weight. Therefore, a dose of 325 mg of ferrous sulfate contains 65 mg of elemental iron. The rest of the weight is from sulfate, which we aren't concerned with in this case.
It is vital to look at the label of your iron product to discern the actual elemental iron content to ensure the correct dose is given.
In the next sections, I discuss Ferrochel, a form of 'chelated' iron and compare it to ferrous sulfate and discuss how they equate in terms of dosing for elemental iron content.
What Is Ferrochel?
Ferrochel is a patented form of chelated iron by Albion. Specifically, it is known as ferrous bisglycinate and it is iron that is bound (or chelated to) two glycine molecules:
It is promoted as having better absorption and tolerability compared to other iron forms, and most report results that confirm this (this is discussed further on).
In addition, it does appear to have fewer drug interactions than other types of iron since it is already chelated. Unchelated iron, such as ferrous sulfate, can bind to medication, forming insoluble compounds that cannot be absorbed.
Elemental Iron In Ferrochel
Just like ferrous sulfate, Ferrochel (ferrous bisglycinate) contains 20% iron by weight. This is illustrated by the following image of a NOW iron supplement label:
Doing some quick math to confirm, 20% of 158mg (the entire amount of Ferrochel in this specific product) comes out to 27mg.
Since ferrous sulfate and Ferrochel contain the same amount of elemental iron (20%) by weight, they are easy to compare in that regard.
However, that is not the full story and 1:1 conversion does not apply between these two different forms of iron.
Multiple studies have shown that Ferrochel is far more absorbable than ferrous sulfate.
One study found that Ferrochel, per dose, is about 70% absorbed, and has a bioavailability (i.e., rate and extent of absorption in our body) that is 3.7 times the amount of ferrous sulfate products.
This graph below represents the relative absorption of different iron compounds. The difference with Ferrochel is clearly visible.
Source: Brian & Hallberg, Acta Med Scand, Supp 368, 1960, Pineda & Ashmead, J Appl Nut, 1994.
There are many reasons why Ferrochel is better absorbed than ferrous sulfate, such as the fact it appears to be more resistant to breakdown in the stomach and isn't inactivated as readily in the GI tract. One study stated the following regarding this matter:
As mentioned, iron bis-glycinate chelate has been used for food enrichment and for supplementation. Due to its chemical structure (consisting of a covalently bounded iron molecule to an organic ligand, in this case glycine), this form of iron can be partially resistant to the action of enzymes and to the binding action of substances naturally present in food such as metals, dietary fiber, phytates, and phenols, with which the iron can form insoluble compounds.
Comparing Ferrochel to Ferrous Sulfate
Although you could compare two products for their elemental iron content (ferrous sulfate vs. ferrous bisglycinate chelate in this case), it is difficult as there are significant variations with absorption, even when the same amount of elemental iron is provided.
Multiple studies have shown that lower doses of ferrous bisglycinate chelate can provide similar effects to higher doses of ferrous sulfate.
On such study, published in the Journal of Perinatal Medicine, found that 25mg of ferrous bisglycinate (i.e., Ferrochel) was comparable to 50mg of ferrous sulfate in preventing iron deficiency (ID) and iron deficiency anemia (IDA) in pregnant women They reported:
The study demonstrates that a daily dose of 25 mg ferrous iron as bisglycinate from 15–19 weeks of gestation in healthy women with a normal pregnancy matches the effect of 50 mg ferrous iron as sulfate in the prophylaxis of ID [iron-deficiency[ and IDA [iron-deficient anemia].
Below is a data table published from the study that shows the effects of 25 mg/day of iron bisglycinate and 50 mg/day of ferrous sulfate. Although the table contains far more data than necessary for our purpose, it points out how similar these two doses were regarding their effects in the body.
Additional studies, such as the one published in Nutrition Journal, show similar results. The Nutrition Journal study in particular also noted that iron bisglycinate chelate was more efficient for maintaining higher ferritin concentrations than the same dose of ferrous sulfate.
All this is to say that even though Ferrochel and ferrous sulfate are both 20% iron by weight, Ferrochel is more absorbable and has more significant effects at the same dose.
Converting Between The Two
So, while we can equate the elemental iron content between ferrous sulfate and Ferrochel products, they likely will produce different effects on blood iron levels, even at the same elemental iron dose (for all the reasons discussed above).
There, unfortunately, is no 'conversion factor' between Ferrochel and ferrous sulfate concerning their effects on iron levels in the body.
Nevertheless, we can at least calculate the elemental iron in the example product you mentioned in your inquiry to us. It was recommended that you give your child 40 mg of elemental iron using a ferrous sulfate elixir that contains 220mg/5 mL.
Since ferrous sulfate contains 20% elemental iron by weight, a 220mg dose (5mL) would equate to 44mg of elemental iron.
The Ferrochel product you are looking at is Natures' Nutra Easy Iron:
This product contains 5mg of elemental iron per 1mL from Ferrochel. Therefore, to get to 40mg of elemental iron, you would need to give 8 mL. However, as discussed in detail above, Ferrochel iron is far more absorbable and this dose will likely be above what your child needs.
It's hard to give specific advice on how much less to use of this Ferrochel product to get comparable results to ferrous sulfate.
If we go by the results studies have shown, even doses of Ferrochel that are half that of ferrous sulfate have very similar effects. The study we discussed above showed that ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prevention of iron deficiency and anemia during pregnancy.
While this gives us an idea of how to compare Ferrochel and ferrous sulfate, we can't safely extrapolate this data to other populations, such as for the treatment of anemia in children. Although it would probably be safe and effective to give less Ferrochel than ferrous sulfate, you should speak with the doctor first for an appropriate recommendation.
One last point I wanted to discuss is the safety of Ferrochel. It appears to have a far higher margin of safety compared to other iron products. This seems somewhat counterintuitive since it is absorbed so much better.
One study even found that the LD 50 (a way measuring acute toxicity) for iron from Ferrochel (referred to as the amino acid chelate) was 2.6 times higher than Ferrochel. This is most likely due to how our bodies process this specific form of iron.
It also seems that Ferrochel causes less GI intolerance than other forms of iron.
One study summed it up as follows:
While many forms of iron will break apart in the GI tract, ferrous bisglycinate chelate does not (1). This may be part of the reason it is generally better tolerated than other forms of iron.
Overall, Ferrochel is a safe and effective iron choice that, like ferrous sulfate, contains 20% elemental iron by weight.
It does appear to be far more bioavailable than ferrous sulfate and studies show that at similar doses, Ferrochel has more significant effects on blood iron levels and associated measures.
There is no simple conversion between Ferrochel and ferrous sulfate past the elemental iron content but you likely would need less Ferrochel to have similar effects to ferrous sulfate.
If the doctor recommends a specific form of iron, it would be prudent to have a discussion with them before making any changes to therapy.
- Elsevier ClinicalKey: Iron Salts (Accessed 1/28/19)
- The absorption and metabolism of iron amino acid chelate. PubMed (Accessed 1/26/19)
- Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial. PubMed (Accessed 1/26/19)
- 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. Bactrim Prescribing Information (Accessed 1/25/19)
- Absorbability of different iron compounds. PubMed (Accessed 1/25/19)