Thyroid UK

Vitamin D Query

I've been taking Vit D3 and K2 for about a year (40,000iu a week of D3). A blood test at the end of January showed my D3 was 250nmol/L. The GP said to stop taking it until after the summer then start taking 800iu a day.

From looking at other posts it seems 100 - 150 nmol/L is the optimal range. How long will it take my levels to get down to this and should I take more than 800iu when I start again?

(Also, I'm in Scotland - we don't have summer!)



9 Replies

No-one can say how long it will take to get your level down. I would suggest you stop your D3 and retest in 3 months. See where your level lies then. To maintain the recommended level we all vary, some may need 1000iu, some 2000iu, but those would be the average.

It's recommended to retest Vit D once or twice a year. Fingerprick blood spot tests are available to do at home. City Assays do one for £28, they are the lab at NHS City Hospital in Birmingham.


Thanks, SeasideSusie, I stopped taking it as soon as I got the results. I'll wait a few months then test it again.



WOW! That does sound high. I have been prescribed 800iu vit D3 daily for 8 months.

My level was 49nmol/L before prescription. Level has now gone to 52nmol/L so it has only gone up marginally. UK ideal 50 above according to my GP. However, USA video I watched suggested better 70 above. I have read other comments here saying thyroid conditions require an optimum level but I'm not sure what was suggested.

Hopefully, you will get better info soon. Take care. I hope it doesn't take long for you to be at your ideal level.


The UK recommended level is 100-150nmol/L. GPs don't know much at all about nutrition and just go by NICE saying < 30 is deficient, 30-50 is insufficient, and >50 is adequate, but adequate doesn't mean ideal, recommended or optimal according to the Vit D Council or Grassroots.

Grassroots' Disease Prevention Chart shows why we should get our level up

The US unit of measurement is different from ours, they use ng/ml and their recommended level is 40-60ng/ml

You can see that your prescribed 800iu daily is pretty ineffective in increasing your level if you've only gone up 3 points in 8 months. I went from 15 to 192 in 2.5 months by a sensible supplementing dose. You'd be better off buying some 5000iu softgels and taking one daily then retesting in 3 months, you should have a nice surprise!

Don't forget D3 has important cofactors that should also be taken


Thank you SeasideSusie,

I do know my GP is not up-to-date on much. Especially with regards to autoimmune disease. She was extremely reluctant to prescribe vit d.

I am still researching, learning a lot. I still have a long way to go with that. I am not confident in starting self supplement s yet, but I am working on it.

I am getting so much more confident using this site though. I currently am challenging a consultant opinion via PALS. I am determined not to be treated less than, during consultations within the nhs. If I don't agree I do challenge now.

Currently, I have just 2 outstanding appointments. I have been on a merry go round for the last 2 years! I have one dental appointment in April at sjogrens specialist centre. One appointment with rheumatologist planned for June.

In the next week, I intend to change my pharmacy because they keep messing the prescription up. The following week I plan to change GP, she has been my GP for 27 years.

Although I suffer flare ups good and bad days, I feel much stronger with support here.

Thank you for sharing, caring and advice.

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I noticed your post on the Crohns and Colitis Forum - asking for suggestions to help yourself. Are you gluten free ? - also dairy free ? Try one thing at a time and monitor what helps .... apologies if you already are GF - have not had time to read all your posts :-)


Hi Marz, I'm not gluten or dairy free. I have thought about going gluten free for my Hashis but I'm not sure if it would make much difference to me. I don't really have any gluten intolerance symptoms. However, I might try it for a few weeks to see if it makes any difference. The same with dairy - I don't believe I have any symptoms.

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Symptoms are often silent. As you have colitis you will have inflamed areas in the gut - gluten only adds to this inflammation - as does dairy. Perhaps you have found other causes for your colitis ?


I thought it was caused by taking ibuprofen for me - that's the only reason I've had a flare up over the last 20 years. I like my bread and dairy (live on a dairy farm) and don't want either to be the cause!

But you're right - I should look into it at the very least.


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