This is a summary of what I have read up and found out about iron supplements over the past few years. I am not in any way medically trained. You are strongly encouraged to check every detail before making any decisions for yourself.
Products are mentioned by name but this is not intended as an endorsement or promotion. Other products might be as good or better. There are no affiliate links.
Excess iron can be not just marginally a bad idea but positively dangerous.
If you supplement iron, ensure you get tested regularly.
Although there are clues to iron deficiency, there is no way of knowing for sure other than by testing. There are no obvious clues to excess iron.
Iron Blood Tests
If you are unfamiliar with the various iron-related blood tests, you might find a reasonable and fairly short introduction here:
https://labtestsonline.org.uk/tests/iron-tests
There are equivalent sites in several other countries.
What is an Iron Panel?
The term "panel" is widely used in medicine in the USA to refer to a group of related tests.
Iron
is a major issue for health but it is not simple. It is important not
to focus on one test to the exclusion of all others. However, all too
often that is exactly what happens - only ferritin is tested and the
result is then used, on its own, for diagnosis. The effect of that is to
miss iron issues which are not reflected in ferritin levels, or when
the ferritin level is affected by things other than just iron. Ferritin
levels rise when someone is affected by inflammation. At the very least,
this can mean a ferritin result that looks to be within the reference
interval when, without inflammation, it would be below the lower bound.
There is no formal definition of "iron panel". The precise tests which constitute an iron panel vary from one lab to another. Quite possibly, two organisations which use the very same lab will have agreed different sets of tests. And with iron it is sometimes perfectly reasonable to substitute one test for another.
If
you have iron tests performed by your GP, you might see different
actual tests to those performed in a hospital context, especially if
they use different labs.
Some results of iron tests are actually derived rather than measured.
This is a collection of a number of iron-related tests you might see mentioned:
- Serum Iron
- Ferritin
- TIBC (Total Iron Binding Capacity) & UIBC (Unsaturated Iron Binding Capacity)
- Transferrin
- Zinc protoporphyrin
- FBC (full blood count)
- Haemoglobin
- Haematocrit
- Soluble Transferrin Receptor
Test Preparation
Your doctor may request that you fast for 12 hours prior to some iron blood tests. In this case, only water is permitted. You should not take any iron tablets for 24 hours before the test. Iron is absorbed rapidly from food or tablets, and can make your blood iron levels falsely high.
https://labtestsonline.org.uk/tests/iron-tests
Interpreting ferritin levels (NICE Clinical Knowledge Summary)
Serum ferritin level is the biochemical test that most reliably correlates with relative total body iron stores. Low levels indicate low iron stores, except in women who are in the second or third trimester of pregnancy.
In all people, a serum ferritin level of less than 30 micrograms/L confirms a diagnosis of iron deficiency.
Ferritin levels can be difficult to interpret if infection or inflammation is present, as levels can be high even in the presence of iron deficiency.
Medichecks Reference Intervals
Reference intervals (ranges) for iron tests vary by lab.
For example, from information supplied by Medichecks:
A quick blog to record these revised ferritin reference intervals.
Females 18 ≤ age < 40 30 to 180
Females 40 ≤ age < 50 30 to 207
Females 50 ≤ age < 60 30 to 264
Females Age ≥ 60 30 to 332
Males 18 ≤ age < 40 30 to 442
Males Age ≥ 40 30 to 518
The lower limits of 30 are by the NICE threshold of <30 for iron deficiency. Our review of Medichecks data has determined the upper limits. This retrospective study used a large dataset of blood test results from 25,425 healthy participants aged 18 to 97 over seven years. This is the most extensive study on ferritin reference ranges, and we hope to achieve journal publication so that these ranges can be applied more widely.
Types of Iron Supplement
There are several forms of oral iron supplement -
The simple, soluble substances like ferrous sulphate through ferrous fumarate, ferrous gluconate
Chelated iron such as ferrous bisglycinate (Ferrochel)
Various forms of haem iron (also spelled heme)
Ferritin
Iron in the form of pure iron or carbonyl iron
Ferric pyrophosphate
- Liposomal iron
- Plant-based ferritin
- Iron Protein Succinylate (IronAid® )
- Ferrous succinate
Simple supplements, haem and ferritin are each absorbed by different mechanisms. These three mechanisms appear not to interfere with each other at ordinary dose levels.
Ferritin has usually been animal sourced however there are some plant source ferritin products:
https://www.florahealth.com/products/ferritin
https://uk.iherb.com/pr/flora-ferritin-plant-based-ferritin-iron-30-delayed-release-vegan-capsules/105249
In addition, there are oral sprays. The best known in the UK is from Better You though other products are available.
https://betteryou.com/products/iron-10-oral-spray
There are also patches. There are variable reports from working well to not working at all. For that reason, there is no link.
One product sometimes reported to work well contains:
Vitamin C (as Ascorbic Acid), Iron (from Certified Organic Curry [Murraya koenigii] extract)
Simple Iron Supplements
The simple substances do vary with the more complex molecules often regarded as being gentler and less constipating than the basic - that is, bisglycinate is usually preferred to sulphate.
Some people suffer side effects from the simple iron supplements which may include some or all of:
nausea (feeling sick)
sickness
abdominal (tummy) pain
heartburn
constipation (feeling unable to empty your bowels)
diarrhoea
black stools (faeces)
Some report good results from the branded liquid products such as Spatone and Floradix. If you need multiple sachets or doses, and especially if you have to take them for a long time, these can be expensive.
Spatone (per sachet) contains: Iron (Fe2+) 5mg (36% NRV*)
Floradix (per 20ml dose of the basic, "original" liquid) contains: Iron 15mg (107% NRV)
"GENTLE IRON" is a USA trade mark owned by SOCIÉTÉ DES PRODUITS NESTLÉ S.A. and is applied to several iron supplements based on Ferrous bisglycinate.
It is often suggested that you take vitamin C with these simple iron supplements to aid with absorption. However, while this is reported to be effective with Ferrous Sulphate, it is not clear that there is any advantage when taking products like Ferrous bisglycinate where the iron is already bound (e.g. to an amino acid), Ferrous citrate, and some other forms.
All these iron supplements are relatively poorly absorbed. That means the iron which has not been absorbed travels through the rest of our intestines. This excess iron can cause many side effects such as affecting the biome (bacteria, etc., in our gut).
Some research has suggested alternate day dosing can be helpful.
Haem and Ferritin
Haem is a protein which binds iron and enables the iron to perform numerous functions in our bodies. The most commonly discussed one being carrying oxygen in our blood. (There are several types of haem but although they have different functions they are broadly similar.)
Ferritin is a protein which binds iron and enables it to be stored and distributed safely. Often, the level of ferritin in our blood does indicate whether or not we have enough iron. However, ferritin usually rises when we have inflammation.
Haem and Ferritin Supplements
Haem iron and ferritin both wrap the iron up in more complex molecules and they have much less impact on the gut. Some people report doing very well on one or the other.
Some plants contain haem iron but usually at very low levels.
Those who cannot tolerate the simple supplements but need iron, should consider at least trying haem and/or ferritin supplements.
A snippet about why ferritin and haem might be particularly important:
Absorption of iron from ferritin is independent of heme iron and ferrous salts in women and rat intestinal segments.
Ferritin iron is absorbed by a different mechanism than iron salts/chelates or heme iron. Recognition of a second, non-heme iron absorption process, ferritin endocytosis, emphasizes the need for more mechanistic studies on ferritin iron absorption and highlights the potential of ferritin present in foods such as legumes to contribute to solutions for global iron deficiency.
https://www.ncbi.nlm.nih.gov/pubmed/22259191
Haem and ferritin supplements will be more expensive than the cheapest supplements but compared to some supplements, they are not particularly expensive.
Don't forget that black pudding and chicken livers are still available as a good dietary sources! As well as many other meat products.
Supplement Sources:
The simple supplements can be obtained from numerous sources such as pharmacies, and on-line.
Some supplements, ones which are MHRA licensed in the UK, are available without prescription. Oddly, sometimes there are two products with the same active ingredient and potency, with one being prescription-only, and the other over-the-counter. You might need to ask a pharmacist.
Haem
The products that will be found by this search vary in time and could, at times, list no heme supplements. Not recommendations and price has not been considered.
https://uk.iherb.com/search?kw=heme
One threearrows capsule contains around 20 milligrams of elemental iron.
https://threearrowsnutra.com/en-uk/pages/simplyheme
https://www.absolutelypure.com/
Ancestral Supplements
Grass Fed Beef Spleen - multiple sources.
Ferritin
The products that will be found by this search vary in time and could, at times, list no ferritin supplements.
Dosing
Iron supplements usually state their elemental iron content. If you are taking an iron supplement, it is the iron content that is important. However, it is possible that a greater effect can be had if your tolerance and absorption are better, even if on a lower dose (in terms of elemental iron).
Recent research has suggested that some might do better taking their iron supplement on alternate days.
|
Iron supplement and dose |
Approximate elemental iron |
|
200 mg Ferrous sulphate |
65 mg elemental iron |
|
300 mg Ferrous gluconate |
35 mg elemental iron |
|
210 mg Ferrous fumarate |
65-70 mg elemental iron |
|
75 mg Ferrous bisglycinate |
15 mg elemental iron |
How long to treat?
One of the recurring stories is of someone diagnosed iron-deficient. They take their iron supplementation until test results show they have adequate iron. Then they stop.
A few months later, they are suffering from iron-deficiency again.
If you are not absorbing adequate iron from your usual diet, then this cycle of supplementing for a while then becoming deficient again is exactly what would be expected. If that is the case, then instead of stopping the supplementation completely, consider continuing on a lower dose.
There are several reasons for continually losing iron. If this is happening, you must get properly assessed.
Testing
When supplementing with iron it is important to have regular tests. Although iron levels usually change quite slowly, excess iron is very definitely something to avoid. The precise tests used may well vary from one GP surgery or area to another.
Storing iron supplements
Very high doses of iron can be fatal, particularly if taken by children, so always keep iron supplements out of the reach of children.
https://www.nhs.uk/conditions/vitamins-and-minerals/iron/#what-happens-if-i-take-too-much-iron
BNF: Oral Iron Supplements
Brief summary of the products listed in the British National Formulary (not all variations, not all brands) and NHS prices. Some products cannot be prescribed on the NHS, or only in specific circumstances. Data looked up 25/04/2015
Ferrous sulphate
https://bnf.nice.org.uk/medicinal-forms/ferrous-sulfate.html
Ferrous sulphate with ascorbic acid (Ferrograd)
https://bnf.nice.org.uk/drug/ferrous-sulfate-with-ascorbic-acid.html
Ferrous fumarate
https://bnf.nice.org.uk/medicinal-forms/ferrous-fumarate.html
Ferrous gluconate
https://bnf.nice.org.uk/medicinal-forms/ferrous-gluconate.html
Sodium feredetate
https://bnf.nice.org.uk/medicinal-forms/sodium-feredetate.html
Electronic Medicines Compendium
Links to Summary of Prescribing Characteristics and Patient Information Leaflets for each of the main types of iron supplement:
Ferrous sulphate
Ferrous fumarate
Ferrous gluconate
https://www.medicines.org.uk/emc/search?q=ferrous+gluconate
Other References:
NICE
Clinical Knowledge Summary > Anaemia - iron deficiency
Last revised in September 2023
Serum ferritin level is the biochemical test that most reliably correlates with relative total body iron stores. In all people, a serum ferritin level of less than 30 micrograms/L confirms the diagnosis of iron deficiency.
https://cks.nice.org.uk/topics/anaemia-iron-deficiency/
NHS
https://www.nhs.uk/conditions/iron-deficiency-anaemia/
USA Office of Dietary Supplements (ODS)
These links are produced for the USA but contain much that is of potential use wherever you are such as representative lists of iron content of a number of common foods.
Consumer
https://ods.od.nih.gov/factsheets/Iron-Consumer/
UK Food Sources
Guidance
Composition of foods integrated dataset (CoFID)
https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid
Go to the download of: McCance and Widdowson's composition of foods integrated dataset
Open the document (in a spreadsheet such as Excel). Go to tab 1.4. And use column M.
Canada/World Vegan Iron Sources
The 30 Best Vegan Sources of Iron [Chart and List]
By Dale Cudmore
https://vegfaqs.com/vegan-sources-of-iron/
General Articles
Iron: How to Manage When There Is Too Much or Too Little of It| December 6, 2019
Management of iron deficiency
https://ashpublications.org/hematology/article/2019/1/315/422602/Management-of-iron-deficiency
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[i][b]helvella - Iron Document[/b]
This is a summary of what I have read up and found out about iron supplements over the past few years. Includes some information bout tests and meaning of ferritin. I am not in any way medically trained. You are strongly encouraged to check every detail before making any decisions for yourself.
Last updated 28/01/2025[/i]
Link to blog:
https://helvella.blogspot.com/p/helvella-iron-document.html
If you find anything incorrect, misleading, typos, links that don’t work, etc., please let me know. Go to my profile and use the contact details there:
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