Posted by Larry Hoover on March 27, 2005, at 7:47:33
In reply to Re: Vitamin D and depression, posted by tealady on March 26, 2005, at 17:22:12
> > > I, too, am interested in the protocol, and what is a safe amount to take on a daily basis.
> > >
> > > Thanks.
> > >
> > > Tamara
> >
> > Here's a full-text link to an article establishing the safety and efficacy of 4000 IU/day.
> >
> > http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=15260882
> >
> > Lar
> >
> Hi Lar,
>
> Good to see you back posting again.Thanks. So am I. I missed me, too.
> I took a quick look at that link , but I can't reach the conclusion (as you seem to?) that it's safe for everyone (or even most people) to take 100mcg VitD3a day long term.
If you looked at the references (hotlinked to some full-text articles, even), you'd see prior work establishing that 100 µg is indeed a physiologic (normal) dose of vitamin E.
> I CAN reach the conclusion that for those living in cold climates (like near Toronto :-))The body has an amazing capacity to store vitamin D, which is how summertime production can more or less get one through the winter. However, with sunscreen and indoor jobs and all that, summertime production is severely limited. Even air conditioning should be considered, as an independent variable. It keeps people indoors.
There's a key quotation in this article: "Future studies of vitamin D supplementation should take into account that it may take a year to reach stable 25(OH)D levels. Although previous work (including our own) has implied that plateau levels of 25(OH)D can occur within five months [5,37], the impression of a plateau reflects the time pattern of sampling; i.e. samples taken at short time intervals can give a false impression of a plateau."
> AND having below range (LOW) 25(OH)D levels to start with , maybe due to not enough exposure to sunlight..or poor absorption , anyway for some reason tending to be low in 25(OH) D and with normal levels of PTH and ionized calcium..then Yes supplementing for a year on 100mcgD3 doesn't seem to hurt.
Just as with thyroid hormones, I would argue that what has been taken to be "normal" PTH is subject to question.
> Actually it doesn't seem to not make too much more difference than just taking 15mcg a day, at least as far as effect on ionized calcium and PTH., although there again I preferred the long term effects of 15mcg on PTH, the 100mcg long term may possibly be suppressing PTH? ..suppressing "hormoan stuff" is not usually a great thing to do long term :-)..unless you really know what your about
Considering that these guys are endocrinologists, I might hazard a guess that they've done their homework. There is a lot of excellent data available through the hotlinks in the references. Check reference 7.
> The 25(OH)D is increased for sure, but I'm not exactly sure what other effects that would have long term on the body.
25(OH)D is also a neuromodulator. It directly affects mood. There are vitamin D receptors, and enzymes dedicated to receive it, in the brain.
> So strange that I would read that article and conclude, yes start off on a higher dose over the first winter ..say 2 or 3 months ..and then reduce long term intake to the minimal required to maintain optimim ionized calcium and PTH etc...perhaps say < 20mcg daily?Certainly, it does require some individual consideration of other sources, but again, from the linked references, you can find evidence that the daily vitamin D flux is at (or above) 100 µg/day. There are blessed few dietary sources of vitamin D. Vitamin D was only recognized as a vitamin when people took a look at how cod liver oil helped treat rickets. We weren't yet sophisticated enough to recognize that it wasn't a vitamin, but rather a hormone, but in any case, exogenous sources of vitamin D are really quite rare. When's the last time you caught a cod and selected its liver from the entrails?
> BTW My own calcium (and corrected) calcium levels are now usually about 2.50 (2.43)mmol/L or so. Do you know if there is way of converting these to ionized calcium..or is it a completely different measurement? (understand Ca++ ions)That, I don't know (the conversion). The normal is 4.4-5.3 mg/dL, for ionized (free) calcium.
> JUst in case his post gives you the wrong impression, I am PRO vitD3 supplementation in colder climates..I'd be doing the same if I lived in one..I even took a tiny dose cod liver oil in England in summer when I was over there :-))
How much sun do you get?
> I just don't think this article is suggesting higher doses is safe for most..or shows that there is a benefit from a larger dose long term.There is some room for interpretation, but the current RDA/DRI levels are ridiculously low. Persons with mood disorders, which keep them largely indoors (like myself), ought to be taking substantial vitamin D supps, IMHO. Long-term supplementation with 100 µg (4000 IU)/day did not result in a single instance of adverse effects, despite their being no restrictions placed on the subjects with respect to potential alternate sources of this nutrient.
> As with all supps, intake should be based on how it makes you feel, and I always go for the minimal dose to achieve this.That's fair. Wellbeing measures were higher in the high-dose group.
> BTW that study also only dosed once a week (I think) ..and then divided by 7 to get the daily dose. This is making an assumption..probably correct (but unknown really) as different results are obtained in some studies with some supps by giving larger weekly doses or the "equivalent" daily doses...maybe to do with absorption etc.
>
> JanI appreciate your questioning of the underlying assumptions in this study. Yes, a once-a-week dosing paradigm might lead to different outcomes than a daily dose providing the same net amount. However, that is exactly the assumption made in determinations of all nutrient intakes; average weekly intake, divided by seven.
Lar
poster:Larry Hoover
thread:410247
URL: http://www.dr-bob.org/babble/alter/20050323/msgs/476160.html