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CLL Support Association
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Vitamin D3 Bests Vitamin D2 for Boosting Total Serum Levels. 600 IU of vitamin D3 significantly more effective in wintertime study

Low serum levels of Vitamin D are common in CLL with a low reading at diagnosis correlating with a poor prognosis. We won't know whether boosting it into normal levels will slow progression until Mayo Clinic release the results of their study, but many of us with low values (self included) find that boosting it into normal levels improves our quality of life, reducing CLL related fatigue.

This Med Page Today article confirms the general understanding that vitamin D3 supplementation is more effective than vitamin D2: medpagetoday.com/PrimaryCar...

US residents please note that if your doctor confirms you are low in vitamin D, due to FDA approvals, they can only write a script for vitamin D2. In this case, just ask your doctor what equivalent over the counter D3 dose you should take and you'll be financially better off.


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Thank you for all of your informative posts.

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Thank you for this. I have upped my dosage of D3 on her suggestion that my levels were low. The message on my phone was to take more (no specifications as to how much to take or how low my levels were.) or come in for a shot.

I will be having a conversation with her re: D levels at next appt.

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I have been taking 5000 IU D3 on the advice of my rheumatologist for 2 years now - he takes 10000 IU -


Must have just read the right article from the beginning. I've been taking D3 and was unaware that D2 existed as a supplement. Also the GP, as far as I'm aware, doesn't prescribe vit D in the UK. At least, I never had the option.

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Hi Mijoed,

Regarding UK GPs, I went to my GP and asked to have my level checked. There is a simple blood test. Results came back for me that level was low so they put me on 20,000IU for a month then 800IU for the rest if the winter. I would have been longer but my Calcium level was low in Feb when I started in a drug trial and they stopped the D3 and replaced it with AddCalD3 that does both.



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