What is the deal with Vitamin D?

[tfarny]

As far as "no megadosing" goes - the definition of "megadose" is whatever happens to be a multiple of the USRDA, which is a load of bollocks if ever there were one. The US RDA of 400 IU / day for D was established decades ago as the minimum dose to prevent rickets in children. Documented cases of D overdose have only been seen in people who accidentally took many thousands of times the RDA, not merely a dozen. Like I said, it's been shown that a lifeguard can get 10,000 iu daily from normal sun exposure, so that seems like a reasonable real-world upper limit to dosage and there are no documented cases of ODs at that level.

[Gunnhild Bruno]

I was browbeaten into trying the D by a bunch of clowns on the CF board.

One should get one’s D levels tested before one starts supplementing. Especially if you feel there’s nothing wrong with you, and you want to take D as insurance. It’s pretty basic common sense. The test is not expensive.

Also, make sure you are taking D3, not the cheaper, less effective, and less safe D2.

Also, don’t let people on CF boards talk you into shit.

I won’t say that D supplementation has made me strong like bull, but I’ve gone from being sick with a cold practically every month in the winter and a couple of times even during spring and summer (which is why I started supplementing) to not having had a single full-blown cold since I started to supplement (going on over a year). For me, that’s a drastic bump up in quality of life.

I‘ve also seen big and unexpected improvements in my seasonal allergy symptoms, as well as a reduction in muscle cramps and twitches, which were actually quite a nuisance for many years.

As a minus, I found that it seems to make my skin more prone to mild acne, which is something I thought I’d left behind me, and uncomfortable menstrual symptoms I thought I’d out-aged have returned (although not, thankfully, with the same intensity they had when I was younger). Make of that what you will--could be coincidental, and it doesn’t have a lot of application to men, I guess, but it may be some anecdotal indication that D supplementation may have some effect on some sex hormones.

Obviously, YMMV. If you’re not already feeling kind of crappy (and even if you are), tread wisely--it’s generally stupid to just supplement take fat-soluble shit without a reason.

If I could find a decent cod liver oil at the health food store, I’d take that instead, but most of the stuff out there has had the vitamins removed and then added back in synthetic form anyway.

[Mark Rippetoe]

Spar, you're normally quite a sensible gal, but what in the hell could possibly be dangerous about taking 5000 units of D? It takes a sustained intake of 50K units over several months to produce symptoms of hypervitaminosis D, and nobody here sits down to a plate of polar bear liver every night. Why should there be a test? Why is it stupid to supplement A, D, and E? I have been for 35 years and all that's happened to me is that I got old.

[Will Morris]

"nobody here sits down to a plate of polar bear liver every night"

In less than two weeks, you could very well be doing just that.

[Mark Rippetoe]

That's the sea creature I actually had in mind.

[Gunnhild Bruno]

Spar, you're normally quite a sensible gal, but what in the hell could possibly be dangerous about taking 5000 units of D? It takes a sustained intake of 50K units over several months to produce symptoms of hypervitaminosis D, and nobody here sits down to a plate of polar bear liver every night. Why should there be a test? Why is it stupid to supplement A, D, and E? I have been for 35 years and all that's happened to me is that I got old.

You're right--I kind of tossed that off late at night was less than precise, and "stupid" was a flippant word choice.

I think there's little danger with E, although I guess there are as many crappy studies that say higher doses of E and other antioxidants are correlated with increased rates of death as there are crappy studies that say they are correlated with lower rates of death. So for me, that's more an issue of whether or not I think it's worth the bother unless some therapeutic need exists.

A is likely hard to overdose on, but I tend to not really want to get it from pills. It has a complicated relationship with D that nobody seems to understand clearly, and there's some theories that I find credible that taking it when supplementing D can cause weird effects, depending on the form and the ratio. I prefer trying to get it from food.

D, on the other hand, should be approached with at least some caution, it seems to me. People always quote that factoid that the body makes 10000 IU from 15 minutes of sunlight, but they don't take into account that the body can turn off the conversion of D from sunlight when it has enough, and there's a built-in throttling effect that you don't get when you take it orally. Problem is, nobody has properly researched what "enough" is. The body stores D for a while, so it accumulates over time if larger doses are taken.

To me, it seems the risk is not toxicity, which I agree is probably really hard to achieve, so much as unknown effects on blood calcium levels. Higher D levels might contribute to calcium deposits in the arteries (and other tissues) in some people, and nobody seems to be able to determine exactly what "high" means. It probably differs by race and other genetic factors that, of course, don't get studied well. Not to mention diet, individual peculiarities, etc. So 5000 IU long-term seems an unnecessary level of risk, but I would think it would be fine to take that for part of the winter in northern latitudes or if you live a vampiric lifestyle. My mother, who has been a renal nurse for over 25 years, says that she sees more problems with calcium deposits where they should not occur now that more people are supplementing with high doses of D. Of course, these people have bad kidneys, but it still makes me think that the lower dose one needs to feel good is wisest. And knowing where you're starting from and keeping track of levels is probably a good idea if it doesn't cause too much hardship.

I could very well be overly paranoid, but I prefer to tread carefully anytime there's a new supplement trend.