My Vitamin D Journey

by Joan Vernikos PhD
December 2015

Early this year I shared on the emerging understanding of the importance of Vitamin D for health, and how you can test and manage your own Vitamin D levels.
Joan Saluting The Sun

My own story around Vitamin D has been fascinating and quite illuminating.

After a summer of sun, swimming and gardening last year my Vitamin D3 serum level was 25ng/ml 25-OHD. That’s average for the US today, so my result was a surprise to me. However Vitamin D3 levels dip as we age plus I have darker skin, which is also a negative factor in Vitamin D synthesis. The recommended normal range is 30-70 so I knew that something needed to change!

To make matters more interesting I was then and we are now entering the Vitamin D winter. This means that anyone living north of a latitude of 35°- almost all in North America and Canada – will get zero benefit from the sun from November to March. You can view this sunshine calendar to see how this works across the globe. 

Most people in North America are deficient in Vitamin D3 even prior to winter. They either don’t expose enough skin for adequate periods of time to make enough and/or do not make up for it from food or supplements.  Some like me may have been taking a daily dose of supplement without really knowing if I need it or if it was enough. Clearly the solution was to measure, and as I noted above my levels as of last Fall were low. I joined the Grassroots Health program ( ) to get my blood levels tested every six months while contributing my data points to their Global Vitamin D Data base.

My blood tests surprised me and I am sharing here what I have learned thus far. As I noted above, in September of 2014 at the end of an active summer and supplementing with a standard dose of 2,000 IU’s of Vit D3 which I had taken as ‘insurance’, my blood level was 26ng/ml or well below the recommended normal range of 30-70ng/ml. Grassroots Health’s data suggest that for every added 1,000 IUs taken the blood level goes up by 5ng/ml. With winter approaching last year I decided to increase my dose by another 2,000 IUs, making my daily dose 4,000 IU. By the end of March 2015 six months later by blood level had increased to 45ng/ml. Out of curiosity I increased my dose by another 2,000 IUs to 6,000/day. My latest Vit D3 blood level in early October and after an active, sunny summer was 73ng/ml. So taking the additional supplements seems to have worked in my case.

Because winter is here I shall maintain this dose of 6,000 IU.  Depending on my blood level at the end of March, I might reduce my intake through the summer by 1,000 or 2,000 IUs and return to 6,000 for the next winter. In my case 1,000 IUs raised my blood level by more than 5ng/ml. Each one of us is slightly different. One dose does not necessarily fit all and depending on your state of health you may need more or less. And it’s important to note that you would need to take extremely high doses for it to be harmful.

My intention is to share my results in the future while we collectively learn more about Vitamin D and its impact on health. Please share your own story with Vitamin D in the comments below.

Here’s to a healthy winter.


  1. D3 supplementation depletes magnesium. Take care!

  2. and magnesium deficiency can lower D3 levels.

    1. Thank you. You are right. Nothing works in isolation. I take 200mg Mg citrate or Glycinate as well and no Calcium. There is plenty added in the food we eat.

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