Thyroid UK
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How long do I keep supplementing?

I posted this a few days ago and would really appreciate some advice. I'm finally feeling really well, thanks largely to the forum and wonder how long I should continue supplementing. I have been reading Dr Brewers book 'The Essential Guide to Vitamins, Minerals and Supplements' and it looks like I'd be ok continuing indefinitely with everything other than the iron and the Vit C (I was really surprised at those!)

Along with (but separate from!!) 112.5mcg levothyroxine, I am currently taking:

200 mg selenium daily

Thorne Basic B daily

200mg magnesium glycinate daily (in the evening)

210mg Ferrous Fumarate daily

500mg Vit C daily

10mg Zinc daily

5000mcg methylcobalamin 3 times a week

5000iu D3 3 times a week with 100 mcg Vit K2

and a Cod Liver Oil/Evening Primrose/ VitA and D multivit on the days I don't take the D3

I would appreciate your thoughts!

I don't want to do myself any harm but neither do I want to undo the benefits I'm feeling!

Thank you all for your support over what has been a truly worrying few months. For all those newbies to the site, please take the advice of these people seriously - they know their stuff and have got me better!!

Trixie 😊

9 Replies

Can you share the info about it not being good idea to be on Vit C indefinitely. I suspect lots of us think that is the most innocuous of the whole bunch.


The book says the RDA in the EU is only 80mg, 100 in the US (for healthy individuals) , same in Austria, Germany and Switzerland. She does suggest the upper safe limit for long term use is 1000mg but I didn't like the bit about it affecting urine and stool samples and having to let doc know . It also suggests that those taking high doses should reduce them slowly over a few weeks 'in order to avoid the so called 'rebound scurvy' effect'. I think, like you I thought it was innocuous and was quite shocked to see this! It doesn't affect me but, for info, there's also a bit that says that those 'known to be recurrent stone formers.... and people with renal failures should restrict their intake to 100mg.'

The one that worried me the most was iron. I had presumed that as I am only taking one a day I could continue but unless I'm reading it wrong, it appears I'm taking way more than the 17mg which she states is the upper safe limit for long term use. (The box says each 210mg tablet contains 69mg of elemental iron.) it was that that really prompted my post as I was quite happy to continue supplementing forever if it was going to keep me well!!



The only way for our bodies to be rid of iron is through giving blood, or menstruation.

It's accumulative; unless I was directed by my doctor due to lab results--I would never supplement with iron.


As SlowDragon says, what's the problem with Vit C? I thought any excess was pee'd out. Also, if taking too much one would get diarrhoea so you'd cut back anyway.

As for the others, I'd certainly retest Vit D once or twice a year if continuing to supplement as excess is stored rather than pee'd out like B Vitamins.

I think I'd keep an eye on zinc as well, it should be balanced with copper I think.


I've also read that zinc should be balanced with copper which is why you should not take mega doses of it.


For Vit D she says that the upper safe limit is currently 25mcg per day (and gives the conversion to UI as x40) and that other countries have much higher - Australia and New Zealand 80mcg. So, I thought my dose seemed well within? Have I got this wrong? My results have improved from 39 to 95 in the last four months which I know is now replete. Do I continue to supplement to keep them there?? It's all so confusing! I was thinking I'd do a Blue Horizon test in a month or so to see where everything is. I think my doc would have a fit if I said I was feeling well but could she please do umpteen new tests! 😏


Vitamin D research states maximum safe amount you can take per day is 10,000IU however you should only be taking this dose if you are very deficient.

If your result is higher e.g over 75nmol/L then you only need about 2,500IU per day. Then once you get to 100nmol/L you need even less.

The problem with someone stating you only need x or y dose that it ignores things like body weight, age, lifestyle and genetics which make us individuals.

Generally if you are heavier/bigger you need to take in more vitamin D than if you were thinner. If you go out in the sun all the time and young, generally you will need less vitamin D than someone who is old.

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Iron - have a test a minimum of every 6 months while taking that amount of ferrous fumerate. Your aim is to get your level to a certain number e.g. half way through the reference range then keeping there. This is done by taking a maintenance dose where you either take lower dose iron supplements or cut down the number of times you take an iron tablet to a few times a week. This is because too much iron is toxic.

vitamin D - you should have a test every year and alter the dose to stay around 100.

Vitamin B12 ( methylcobalamin) and B complex - they are water soluble do you pee the excess out plus there is no research so far that shows they are harmful in those with good kidney function.

Cod Liver Oil and the vitamin A and vitamin D multivit - How much vitamin A has it got in it? As unlike vitamin D you ingest lots of vitamin A from food. Excess vitamin A is toxic and is linked to an increase risk of cancer as it is a fat soluble vitamin. (I do need to check but I'm sure the maximum daily amount you should take in is something like 10,000IU like with vitamin D. However for vitamin E it is something like 2,500IU)

Evening Primrose - only heard it interacts with medications and can increase bleeding so check any other medications you are on.

magnesium - you will have diarrhoea if you take too much.

vitamin C - water soluble plus you are likely to have diarrhoea if you take too much

zinc and selenium haven't researched taking doseages.

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Thank you all. Loads of useful stuff as always. I think I'll just start taking the iron, Vit C / Zinc, and Vit D once a week and see how I go. That's reassuring about the Bs as I'm sure that's what has made the most difference to me. The Endo suggested the selenium to help with conversion and I've not been taking it that long. The Cod Liver Oil Evening Primrose capsule I take (Boots) says it has 50% of the RVI of Vit A and 100% Vit D.


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