Quote:
Originally Posted by saffydaff
I live in Scotland where we don't get much sun. I'm on lat 56, same as Churchill in Canada I think.Should we take vit D all year round?
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First you need to raise your 25(OH)D status to around 55ng/ml and that will take roughly 1000iu for each 25lbs you weigh +100iu/d for each extra 2.5lbs. If you take that amount DAILY for 3 months and then get a
$40 Grassrootshealth D Action postal 25(OH)D test you will then know if you have achieved the level associated with
least chronic disease incidence.
By that time there will no longer be any chance to get
vitamin D3 from sunlight in Scotland. let alone sufficient to meet your total daily needs rather than just the 1000iu that calculator provides an estimate for so it would be worth keeping on at that rate until the end of April, then if you are able to get regular near full body midday sun exposure in Scotland you MAY want to reduce your daily supplement intake by 2000iu/d over the summer months. But it isn't essential. It is far better to have a stable high 25(OH)D level than one that swings from high to low.
Among other things Vitamin D is used for signalling in the body so lots of regulating mechanisms are dependent on a steady availability of D3 and need to adjust their response to the current 25(OH)D level. So there can be, if your status changes rapidly, an adjustment period, in which the fine tuning of other systems (such as immune function) catches up. An example of this is when people go away for a winter sun holiday, lay on the beach all week (thus raising 25(OH)D rapidly) only to catch an infection on the flight home (because their immune system is still disregulated by the sudden change) or a couple of months after getting home as their 25(OH)D drops fast with resulting further disregulation of the immune system.
I've got the full text (a non copyright prepublication version) of this Vieth paper
How to Optimize Vitamin D Supplementation to Prevent Cancer, Based on Cellular Adaptation and Hydroxylase Enzymology REINHOLD VIETH explaining this in more scientific terms if anyone wants to go into it in more detail PM your email and I'll attach a PDF copy.
But the take home message is to try to keep your 25(OH)D both high and stable. So if you are planning a tropical winter sun break, use D3 supplements before and after, but not while you are sunbathing during the tropical winter sun holiday . That way you will smooth out the height and depth of peaks and troughs of 25(OH)D and minimize the periods of imbalance in immune fuction as the system plays catchup with rapidly changing D3 status.
The Grassrootshealth trial is for 5 yrs and you can get tested twice yearly if you want. You'll probably know after a couple of tests how your body responds to D3 and be better able to see what intake is necessary for you living in Scotland. But whereever you live there is no risk accruing to those who use less than 10,000iu/daily/D3 EVEN in the presence of ample sunshine.
If you have any doubts whatsoever read the evidence here.
Vitamin D and Cancer Mini-Symposium: The Risk of Additional Vitamin D Reinhold Vieth