Vitamin D, Calcium Supplements May Be Unnecessary | Hacker News Reader

Vitamin D, Calcium Supplements May Be Unnecessary

businessweek.com

5 pointstocomment5 comments

The article is confusing. It doesn't state how much vitamin D is too much or what the consequences of having too much vitamin D are. Then there is this paragraph:

"The body also makes vitamin D from the sun, although in the winter in the northern half of the U.S., the sun is not strong enough for vitamin D production. While their diet may not supply enough vitamin D for many people, the sun provides enough to make up the difference, the report said."

Apparently, in the winter people should take vitamin D supplements.

I read it to be saying that even in the north, (I live in Seattle) you are fine with the vitamin D from your diet and the sun that you get.

However, I can't see how that's possible. For at least two months of the year, I basically only see the sun on weekends, and it's usually cloudy. (Plus, I don't eat the vitamin D fortified foods they mention, but that's probably not true for most people here).

Any thoughts. Could there have been some flaws in their study?

If you eat fortified food and get out in the sun enough, then sure, this may apply to you. But if, like me, you try not to eat food that's been heavily processed/fortified and you live where days are short in the winter, then you still might not be getting enough vitamin D in your diet. If the tests are suspect, you'll never know...

If this is the study I'm thinking of, these are bone/calcium specialists looking at calcium and Vitamin D and are judging required D based on calcium in the body.

Given that D has a lot more functions than that, it's ... limited in utility at best. I have heard that D testing is a bit messy, though.

For a counterpart observation, if you're white, at a low enough latitude and get (nearly) whole body sun exposure for 30 minutes during the summer, your body generates a self-regulated amount of D of 10,000 IU (or maybe a bit more, I forget exactly how much). Regulated in that staying out longer won't increase the amount you get per day.

That suggests various obvious things, especially about safe maximum levels of D in your body.

One final comment: as far as I can tell, with the exception of Vitamin C to a certain extent, you simply cannot study one or two required nutrients in isolation. E.g. if you have too little of X, Y or Z you may not absorb enough D in your body. Ditto for too much of M, N or P. Then there's questions of "how much fiber in the meal?", is there enough fat for the fat soluble stuff, etc. etc.

And our general knowledge of digestion and what goes on in the digestive tract it pathetic. Did you know that you've got more bacteria in your gut than you have cells in your body?

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