Reviewed by Varnada Karriem-Norwood on May 02, 2012
Ethel Siris, MD. Dir., Toni Stabile Osteoporosis Center. Columbia University Medical Center. President, National Osteoporosis Foundation. Director, National Osteoporosis Risk Assessment Study (NORA).
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Ethel Siris, MD: Many people are saying up to 1200 units every single day. Why? Because you need that much D to absorb the calcium, you need that much D to have good muscle function. If you have less D in your system, you won't absorb the calcium, your muscles will be weaker and that's bad. There's also some new data that D is good for lots of other things. There's some fascinating data that greater amounts of D may reduce the incidence of certain infections, may help the immune system, and may actually have some beneficial effect in the prevention of breast, prostate, possibly colon and lung cancer. D does many things. So you want enough. Now, can you get toxic from D? It's really, really, rare. You'd probably have to take in excess of 10,000 units daily for long periods of time to even have a shot at getting D toxic, which means your calcium level goes up and you don't do well. The doses we are talking about 800 to 1200 units a day are not associated with any toxicity. You can probably take 2,000 units a day without tox, without any risk.
Narrator: You can't get it in foods? Enough of it in foods?
Ethel Siris, MD: D is mostly in oily fish, cod liver oil. So if you eat sardines 7 days a week, there's a good chance you'll have a better D level. D comes from sunshine on the skin, and from very, very selected oily fishy type foods. That's a problem. It means that if you're not you know getting sunshine, or if you're older and the sunshine doesn't work, or you're putting on sunscreen, you have a high likelihood of being D insufficient. I'm fascinated by the fact that although we still don't have a government statement about D requirements, I think we will. The manufacturers are getting savvy, and many of the calcium supplements that used to have 200 of D in the pill now have 400 D in the pill. It's interesting that multi-vitamins sometimes have D2 instead of D3. What does that mean? Vitamin D2 is from plants, it's ergocalciferol. It comes from plants that are irradiated by sunlight, and a lot of vegetarians prefer a multi-vitamin that has a plant form of D. Plant form of D, D2, is perfectly good D, but it's not quite as effective, and you can't count that as 400 towards your 8 to 12.