Vitamin D - a word of warning

Just posted this on Everyday Living, but it’s relevant for people who only use this forum too.

Just had a call from my GP. I saw her before Christmas because I’d been having worse than normal fatigue and weakness and wanted to rule out other things before blaming my MS. Had a load of blood tests and some of the results are in…

My vitamin D level is 345! WAY too high!!!

So a word of warning: please don’t make my mistake, i.e. popping high dose vitamin D3 capsules and not getting a regular blood test to check that your levels are in the 150-200 nmol/l range - because above that is really not a good idea!

I cannot believe I was so stupid! I had regular tests in the first year I started taking D3 supplements, but not since. Doh!

Karen x

For anyone thinking, “Eh?”, vitamin D3 supplements are recommended these days for people with MS. I found 5,000iu wasn’t enough to get my level up to 150nmol/l so I started alternating 10,000iu with 5,000iu a day and then assumed that would be fine so stopped getting tested. BAD assumption - I’ve clearly been taking far too much for a while. Don’t let this put you off taking a D3 supplement though - just make sure and get regular tests.

Oh Karen! Poor you, hopefully now you will start to feel a bit better as your levels come down. Are you having to stop completely for a while? Thank you for the warning. I have never taken Vitamin D as a supplement but if I need to I will get my levels checked. Sam x

While your doctor may have panicked about a 345nmol/l level vitamin D EXPERTS know that 500nmol/l is the level at which adverse events may occur.

Go check our the GRASSROOTSHEALTH site and you’ll see they say 10,000iu has no toxicity because it doesn’t raise levels above 200ng/ml = 500nmol/l.

When 25(OH)D levels get above 150nmol/l the body doesn’t hang on to it so tightly and the rate of disposal speeds up.

So while at deficiency levels 25nmol/l the half life of calcidiol is 12 weeks above 150nmol/l it’s only 2weeks so stop taking vitamin D supplements for a couple of weeks and your level will be half the current and absolutely ideal.

As you can’t get vitamin d from sun in the UK until March you can resume taking 5000iu in 2 weeks time but remember to get 25(OH)D tested twice a year. CityAssays (Birmingham NHS Path lab) do them by post for £20 if you buy 10 packs and share with friends. The main problem with higher vitamin d arises from the fact that many people don’t have sufficient magnesium or vitamin k in their diets so aren’t able to countbalance the problems of too much calcium in the system. A little vitamin a is also useful. The Vitamin D Council have a page on Vitamin D Cofactors that is worth reading.

Sorry Ted, but I think that your reply is rather naive. I went to my GP’s because I had been feeling ill for months. My level was 345nmol/l by then. It is the only test to have come back abnormal (thankfully) and, having now looked into it, it’s clear that my symptoms are signs of toxic levels of D3: they match perfectly!

Moreover, other websites state that the toxicity level is considerably less than 500nmol/l. Thus it appears that no one actually knows what the toxicity level is - I assume because no one has studied it in sufficient numbers. It’s all guesswork.

I was unbelievably foolish to assume that (as you say!) 10,000iu a day is fine so taking less than that was nothing to worry about. It clearly is!

As I said on Everyday Living, I am a firm believer in vitamin D3 supplementation for MS. However, we should none of us be complacent that 10,000iu a day or even 5,000iu a day is fine to take without regular blood tests. We are all different, the science is incomplete and websites stating things like “10,000iu has no toxicity” should be read with healthy scepticsm. Less than that has certainly proven toxic for me.

What are the symptoms of toxicity? What are your symptoms? I’ve upped mine to 8,000 iu for the last two weeks. I have read that vit d3 toxicity is very rare and has only occurred in people taking more than 40,000 iu a day.

I suppose you just have to monitor your levels.



Am I okay to take vit D3 even though it isn’t low? I only purchased the holland & Barrett 25iu is it I take 1-2 of these everyday

The symptoms are things like fatigue, nausea, weakness, lack of appetite, digestive spasms and constipation/diarrhoea - all of which I have had in the past few months. I originally thought that my MS was progressing and my IBS was playing up, but then (and it sounds daft!) all my nails broke and kept breaking as soon as they slightly regrew so I wondered if something might be wrong. I don’t know if the nails are related, but it got me to the GP’s so it’s rather good they broke! I’d read the same stuff about it being hard to take too much D3 - it appears that it’s rather easier than these websites make out! So I’ll be having regular tests from now on. Vitamin D3 is an important supplement for people with MS so I won’t be stopping permanently - I’ll just be making sure that I keep my level between 150 and 200nmol/l and no more. Karen x

MrsC - did you mean 25mcg? That’s 1000iu so two of them a day would be VERY unlikely to cause excessively high levels, but you should monitor them anyway. Most neuros seem to be recommending 4-5000iu a day. I was taking 10,000iu 4 days a week and 5,000iu 3 days a week. I guess that I will end up back at 5,000iu a day when my levels are better, but it might take a while to sort out. What I won’t be doing any more is taking supplements without properly monitoring the effects! Kx

Just looked it up yes it’s 1000iu So even though I’m not low they are safe to take?

According to everything on the internet (a lot of which is written by doctors), yes.

My warning is about the fact that these same people say that 10,000iu is safe, but it has been shown not to be for me.

In the UK, it’s necessary to take a high dose supplement to get a D3 level in the region of 150nmol/l, but we shouldn’t be taking more than our bodies need, and that amount will vary between individuals.

Remember that the NHS’s “low” and “normal” vit D levels are very much less than recommended by the MS medical community.


MrsC, I am on the same dose as you - i.e. normal supermarket “hi-strength” (I take two a day). I’ve always been sceptical of the super-high doses favoured by some here.

I can’t tell you if it’s always safe for ALL people, even at the comparatively low doses you and I take. But I can tell you I don’t intend to change my regime.

I don’t think I’m ever going to get my vitamin D checked regularly on the NHS - it’s just not something my GP practice would go along with, unless the patient had been shown to have a deficiency. I did have it checked a few months ago, by cheekily asking the nurse, while I was up there getting my blood checked for something else. She said: “Of course, why not?” It came back absolutely fine - which probably means it would have been low, had I not supplemented at all. But as I seemed to have got the balance about right (more by luck than judgment) I’m not going to tamper with anything.



Hi Karen, I’ve just posted about vitamin d levels as mine have come back high. I take 5000iu a day and my blood test reading was 284. My nurse is saying to stop the supplement and she will re-test in three months. Just wondered from this post how you are now with regards to this. I’m also now concerned as I give my little boy a supplement of 400iu a day too and I don’t want to be doing any damage. On reading up on vitamin d I know it absorbs differently in people too. Apparently if your pale skinned you absorb it quicker from the natural light than someone who is darker skinned. I am a red head with very pale skin as is my little boy. Just thought I’d bring this post up again to try and get more advice xxx

Hi Lisalou, Karen is on holiday and back on 19th (I think).

Perhaps you could make a note and bring post back up after that date… but I’m assuming (hoping) if she felt well enough to go on holiday she is feeling better.

Pat x

Wow I’ve been taking 1400iu daily for 4 months cos my level was 44! GP said level of 50 was ok. Going to ask them to recheck today.

Hi littlekit, 1400 iu is very low… lots of us are on 5,000 a day.

Nothing to worry about hon,

Pat x

Yeah I’m wondering whether I ought to be on more x

It’s really a personal decision. I didn’t start on it till neuro recommended it.

Now I’m very glad I did as over 3 months later I feel like a little light has gone on in my head. Might be my imagination or not linked to Vit D… but something is making me feel better.

Pat x

I started on it cos my sister (who has ME) had low levels and something just twigged in my brain and I thought hmm I bet I have low levels too. So got tested and my level was 44. I’m guessing from what you guys said that this is even lower than I thought x

That’s very low. I was 79 and still decided to take supplement.

Pat x

Oops! Well will get the GP to check again today with regards to upping the supplement. Thanks :slight_smile: x