WARNING about iron supplementation

For nearly 2 years I've been prescribed ferrous fumarate by my GP. Yesterday my consultant rang me and while discussing my thyroid medication also alerted me to the fact that the body can only take-up 15 mg of ferrous fumarate per day. Afterwards I went to check the dose I am taking and it is 280 mg per day, so I thought I must have mis-heard and went online to check, but there was no mistake.

Here's a link I found about potential harm, and, since in nearly 2 years my levels have barely improved I thought others on here would much rather be informed than unquestioningly take whatever you are prescribed.


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As almost always, the article starts on the basis that anaemia is always iron-deficiency anaemia. Does no-one out there understand that there are other forms of anaemia? Like Pernicious Anaemia, Sickle cell anaemia, ... Wiki does a very good list of the various forms:


Having said that (and of course, that is not your fault at all!), I have often posted about taking iron in the form of Haem (heme) or ferritin. Both forms have the iron bound and not nearly so likely to cause gut damage as the "mineral" forms such as ferrous sulphate. I and many others have often suggested consuming liver as a good source of iron.

There are (at least) three separate pathways for absorbing iron from the gut. The one that is used for "mineral" iron, another for haem and a third for ferritin. I do wonder whether the 15 milligram total absorption includes all three pathways? Or does it just count "mineral" forms?


For me the problem is that as a vegan I cannot find good sources of iron that do not also contain phytic acid, though recently noticed sweet potatoes are a relatively good source.


This might have some interest (and not from the meat-substitute point of view):


Vegetable source haem could be wonderful!


That's an interesting report and I can see why they don't yet have useful recommendations for GPs who are those typically in charge of prescribing for patients.

This paper discusses how little iron we absorb from medications/supplements which is why prescribed dosages are relatively large: ncbi.nlm.nih.gov/pmc/articl...

It will be good to see more useful guidance on this.



What is not at all clear is what impact the 90% (or whatever other proportion) of iron supplement that does not get absorbed have on the rest of the gut. It is all very well saying you need to take 5000 milligrams to absorb 500 milligrams (over a month).

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Agreed. Even tho' the guidelines probably won't be amended until there's more research that confirms this finding (particularly in vivo rather than in vitro) it would be good to have some better guidance for GPs who are prescribing these supplements.

Original Shovlin et al paper discussed in DM article: journals.plos.org/plosone/a...

I can't find anything more up to date by Shovlin on this topic: ncbi.nlm.nih.gov/pubmed/?te...

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I agree but remain even more concerned about the negative impact on arteries, veins and blood vessels mentioned in the article. I imagine the gut will heal but think the cardiovascular system is not so resilient.

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I went to check the dose I am taking and it is 280 mg per day

in nearly 2 years my levels have barely improved

You obviously have a problem similar to the one I had, except yours is even worse than mine was.

I took ferrous fumarate 210mg, 1 tablet 3 times a day for nearly two years. Each tablet contained 69mg of pure iron, making a total of 207mg pure iron per day. My levels did rise but very, very slowly.

What got my ferritin levels up close to optimal in the end was going gluten-free, although my serum iron and transferrin saturation are still quite a bit below optimal. I still have to supplement iron, but I only take a couple of tablets a week and this seems to be sufficient to keep my levels from plummeting. If I stop the iron completely for any length of time my levels do drop quite dramatically.

Working on improving and maintaining gut health is very important for anyone with a thyroid problem.

Do you take 1000mg vitamin C with each iron tablet? If you don't it is well worth doing - it helps the body to absorb iron.

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Thanks humanbean, I am gluten-free, have been for over a year, and I do take vitamin C though I can't tolerate 1000 mg, but as a fruit-loving vegan my diet his high in C already. If you have any other ideas I'd be pleased to hear them - I do wonder why our levels remain low.


My iron levels increased on 3 x 210 ferrous fumarate a day and did nothing on 1. So it may be down to absorption.


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