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Thread: Vitamin D, again

  1. #1

    Default Vitamin D, again

    This article by Erik Garnas is a timely reminder that those of us the northern hemisphere may need to be thinking about our Vitamin D levels as winter looms, but that we should also think about it in summer as well unless we are getting a decent daily amount of sun exposure.
    Gilli - DLTBGYD but more importantly KCHO

  2. #2

    Default Circulating Vitamin D3 and 25-hydroxyvitamin D in Humans

    When this paper was published Cholecalciferol the basic form of vitamin d3 was thought to be inert inactive and the active forms were calcidiol (the storage form and Calcitriol the hormonal form were the most important.
    Circulating Vitamin D3 and 25-hydroxyvitamin D in Humans

    We now know better.

    Dietary Vitamin D and Its Metabolites Non-Genomically Stabilize the Endothelium
    This paper shows cholecalciferol in that basic form is NOT INERT but stabilizes the endothelium and enables the signalling modality that inhibits the production of excess proinflammatory cytokines which only happens optimally when 25(OH)D is at/above 50ng/ml 125nmol/l.

    this article explains the way vitamin d inhibits inflammation.
    How vitamin D inhibits inflammation -- ScienceDaily
    and for the nerds here is the science
    Vitamin D Inhibits Monocyte/macrophage Pro-inflammatory Cytokine Production by Targeting Mitogen-Activated Protein Kinase Phosphatase 1

    the most important thing to note here is that the inhibition of proinflammatory cytokines responsible for excess inflammation only happens optimally when 25(OH)D is at/above 50ng/ml 125nmol/l.

    We can only expect our mobile phones to work is the signalling required is present.
    Cholecalciferol when in serum in significant measurable amounts enables the required signalling for inhibition of excess inflammatory cytokines.

    Unfortunately living modern urban lifestyles, wearing clothes and sunscreen, living in polluted atmospheres within 10km of airports or busy roads prevents sufficient uvb reaching ground level and most people will struggle to get 25(OH)D above 40ng/ml 100 nmol/l
    Vitamin D Serum Level by Amount of Sun Exposure

    People living at the latitude of the UK usually require in the region of 6000-8000iu extra vitamin d3 daily to get over that 40ng/ml 100nmol/l threshold.
    Evaluation of vitamin D3 intakes up to 15,000 international units/day and serum 25-hydroxyvitamin D concentrations
    To achieve serum 25(OH)D levels >100 nmol/L on average, required vitamin D intakes of 6,000 IU/d for normal Body Mass Index (BMI), 7,000 IU/d for overweight and 8,000 IU/d for obese.
    and that is in Calgary Alberta where they have 1000 hours more sunshine annually than the UK.

    Normal vitamin d levels in the UK are shown here.

    75nmol/l our peak UK levels at the end of summer is about 30ng/ml in the first image here and at the end of winter our levels are down to just around 35 nmol/l = 14ng/ml
    Last edited by TedHutchinson; 15th October 2019 at 11:00 AM. Reason: typos

  3. #3


    That is most illuminating, thank you Ted.
    Gilli - DLTBGYD but more importantly KCHO

  4. #4


    Grassroots Health has been doing a long-term study of D3

    For several years I was a study participant and paid good money to have them check my D3 levels every 6 months. It was worth it as I started with a level of around 29ng/ml it took me a 6 months of 5000iu/day supplementation to get to 77ng/ml.

    When I was a kid we got cod liver oil capsules every morning in the winter, up until I was 9 and sent to boarding school. I never got flu until I was at boarding school and not getting my cod liver oil.

    I still take 5000iu/day of D3, even though I've moved to Arizona and spend a decent amount of time out in the sun (between 1/2 to 3 hours depending on the day and the temperature) I don't wear sunscreen (but I do wear a hat!)

  5. #5
    Super Member Christelle's Avatar
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    Sep 2016
    Johannesburg, South Africa


    Hugh, Mat had a calculator a while ago to work out how many hours of sunlight you need dependant on where in the world you are.
    I live in sunny South Africa and when I placed my location in the calculator, it estimated that I needed 13 hours of sunlight to have optimal vit d3. I was astounded that in a place where they warn you to keep out of the sun, this calculator wants you to be in the sun. This is when it occurred to me that our forefathers would have spent this amount of time in the sun working the land...

    Good for not wearing sunscreen and well done in spending at least some time in the sun (which is more than what I can say)
    Trust the process, the results will come


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