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Thoughts on Vitamin D


Hi everyone

I hope these crazy Covid times find you all safe under the circumstances.

This is just a theory I have regarding Vitamin D (which scuba and others have posted about often here) and I would like to share a recent result with you.  I have had CML since 2015 and have had a really slow response on dasatinib, followed by unusual side effects necessitating a change to imatinib, and I've been on 400mg since May 2018.  I reached MMR at 24 months and have retained it ever since.

Last year I was fortunate to have 6 months sabbatical and I travelled to China, Eastern Europe and Southeast Asia on three consecutive trips.  During this time I was in the sun very often - for approximately 6 to 8 hours a day.  In the two BCR-Abl tests I had in that time, my levels dropped to a record low - they were around 0.03% before the trips and reached 0.006% and 0.005% (the last one was in March this year).

Here in South Africa we have been on various stages of lockdown since 26 March and various things have been prohibited.  A major prohibition was a lengthy ban on exercise in public spaces.  This, together with my changed work circumstances (having to work from home because of the CML) and the winter approaching in South Africa meant that I have hardly spent any time in the sun since then.

It was no surprise to me that my latest test showed a significant increase to 0.011% (just out of MR4).  I haven't done anything different during this time apart from spending virtually all my time indoors.  It may be a coincidence, but I firmly believe that lower Vitamin D levels are the reason for this increased result!

Now that the ban has been lifted and we're in the last month of winter, I will make a point of going out into the sun for at least an hour each day.  I'll be very interested to see what my next blood test will show and will keep everyone updated.

Best wishes from Johannesburg


Hi Martin,

Most cells in our bodies have the vitamin D receptors (VDR) on their membrane surfaces especially white blood cells. Vitamin D is essential in activating T-cells which fight cancer and pathogens (like Covid-19). What is emerging from research is the amount of vitamin D necessary for maximum effect. Current government guidelines suggest blood levels between 30-50 ng/ml are considered normal - mostly due to vitamin D's role in bone health to prevent rickets. But more recent studies are showing levels between 50-70 ng/ml is the sweet spot for maximum benefit in disease fighting enhancement. Lower or higher blood levels decreases this benefit, but with lower being much more risky. Higher than 70 ng/ml (up to 100 ng/ml), also has just a slightly lower impact. Lower than 50 ng/ml impact on T-cell activation falls off dramatically.

Vitamin D works against CML mainly by causing leukemic blast cells to differentiate and then induce natural apoptosis. I strongly believe high normal vitamin D levels can minimize the chance of CML progressing to blast crisis and it is blast crisis which kills in CML.

The best way to increase vitamin D levels is with noon time sun exposure in summer months. For many this is impractical. I supplement with vitamin D3 (the active form) most days in summer at 5,000 IU's per day. In winter I increase my dose to 15,000 IU's over two days. Even with this high dose, my vitamin D level will fall to mid 50's coming out of winter and rise to near 80 by end of summer. When i am scuba diving, I don't take any vitamin D at all and I never wear sun screen.

Vitamin D along with vitamin C, zinc and quercetin can do more to minimize risk and disease severity from Covid-19 and other virus' until vaccine. In my own experience, once I increased my vitamin D level to where it is now, I have not had a flu, cold, or any other respiratory illness (> 10 years). Prior to supplementation I would get colds and flu like clockwork. I am also undetected for CML and take 20 mg dasatinib every other day.

(Keep in mind blood level of vitamin D does not change very fast (fat soluble). Vitamin D has a two month half life in blood and tissues. Depending on how long your trips were, lack of sun or supplementation over a few days is not likely to have much impact. Also recommended to take vitamin K2 with D (same day) as they work together.)

Hi scuba

Wow!  Thank you so much for taking the time to write me this incredibly detailed response.  So interesting, so practical and so very valuable.  The timing regarding half-lives checks out almost exactly from the time I spent mostly indoors to the increase in my BCR-Abl levels.  Quite incredible.  I haven't been supplementing with Vitamin D at all given that I live in a country where I have about 9 hours of sunshine per day.

From today I'm going to do exactly as you suggest - getting that noontime sun every day - and I will also speak to the doctor about possible supplementation.  I will be very interested to see if I regain MR4 following this small change and will definitely keep you posted after my next test.

Thank you once again - you are an unbelievable source of information here.

Best wishes to all


I would also like to mention something about vitamin D. I have noticed that in cases of people not suffering from cml, vitamin D rises faster than all of us. In our case it goes up with difficulty and goes down very fast .... does anyone have anything to say about this?

Hi Tom,
May be you are right. May be TKI-s cause the levels of vitamin D to go down and we need to supplement with higher dosage. When I started treatment with Tasigna 600mg in Oct 2020 I checked my vitamin D level and it was somewhere in the upper limit of the norm. Three months after that it was “insufficient”. I started to supplement but it increased only a little and is near the lower limit of the norm which is not good. I have increased dosage and sun exposure and will check after 2 months.