hey napay, short answer:
yes take d3. plain 'd' supplementation values are meaningless as far as i'm concerned, because there are about 5 different subtypes. so i couldn't say re: dosage. i have settled on a MAINTENANCE value of 4000 IU per day from a supplement (or sunshine on unprotected skin for less than say half an hour, as long as the solar energy reaching your skin is at least 18... crap i forget the units. but basically if it's warm enough to bare your skin outside in the sun it's probably all good.)
you might agree that MAINTENANCE supplementation is insufficient if you're starting out insufficient or deficient. if so, read on for the long answer:
what you do is get your blood tested so you have a decent baseline serum value. the lab requisition should be specifically
if the doc writes vitamin d3 you can run into problems testing the wrong metabolite. i mean, it's good to know the numbers for the other metabolites but meaningless for long term monitoring.
the supplement you want to take is definitely d3 (cholecalciferol). this form matches that which is naturally synthesized in human skin upon exposure to solar energy. (winter sun isn't strong enough).
d2 (ergocalciferol) is a common alternative synthesized from plants. my view on d2 is, why bother. it is wise to mix in calcium and magnesium when you take your d3 supplement, since d maximizes the body's ability to absorb these nutrients.
regarding supplement amounts, that depends on the result of your baseline 25hydroxycholecalciferol test. also depends on how much patience you have.
i have been advised to get my serum levels up to 125-150 nmol/l. this is a number specified by vieth in his articles, but was relayed to me by one of my health care team. i personally think it could be low, but i'll settle for it for now
upon doing some investigation, i found some articles that let me calculate a daily dose to get to 150 nmol/l, from my 'baseline' (i had already been supplementing at 4400 iu for months) of 72 nmol/l, over a period of 5 months. the daily dose would be 4500 IU per day.
i decided to investigate ways to shorten the 5 month period, since i had such a low d level after months at a similar level of supplementation.
50,000IU per day for ten days was suggested by a local drug info centre, as a quick booster of 50 nmol/l. i obtained some highly concentrated liquid (1,000,000 iu/g) from the pharmacy, with my doctor's help, and took 2 drops each day from an oral syringe. i put it in a spoonful of cal-mag-d liquid to take it. that prescription was around $50 CDN.
then i got my level tested again. at first they accidently tested a different metabolite of vitamin d. (1,25 dihydroxycholecalciferol). i had to go in and explain the problem, and then we did another test to get a comparable 25hydroxycholecalciferol level. it was 149 nmol/l.
for maintenance, i have seen 4000 IU/d recommended in the literature. this is also the daily dose recommended by one of my doctors. of course if i get really good sun exposure on most of my body, without sunscreen, for say 20 minutes on a given day, i would consider that i could skip the supplement that day. i have pale skin. the time of exposure gets longer the darker your skin colour.
now i have a new maintenance dose prescription for vitamin D. it is the same potent liquid but it is diluted with olive oil. typically they would use peanut oil but i asked for olive. i have a six month supply and it cost around $80 CDN. because it's prescription, it's covered under my health plan. i still take it in a spoonful of cal-mag-d liquid, and i take extra calcium as well, and there is magnesium in my daily multimineral.
i will be monitoring my serum 25hydroxycholecalciferol quarterly, at first to ensure that the levels stay over 100 nmol/l all year round.
the vit d toxicity level in my mainstream doctor's computer system is 250 nmol/l. the toxicity of this serum value has actually been debunked in human research (i think this paper is posted elsewhere on the site but i can have a look for it if you want) and natural unsupplemented levels upwards of 450 have been found in south indian outdoor workers. (that's from a paper from the 80s which i imagine is referenced in one of my earlier vit d posts).
kay that's it for now
hope this helps.