There are two types of vitamin D, D2 and D3. It’s important that we know this because one type, D3, is absorbed well and the other type, D2, is not. Unfortunately, many doctors do not know the difference. They may not even realize there are two types of vitamin D, and if they do know there are two types, they may think they are both equally well absorbed or may have no idea what the difference is. I know it seems like a doctor should know these things, but the reality is, many do not.
D2 must be converted to D3 in the body in order for the body to use it. It takes a fair amount of D2 to make a little bit of D3. I’ve seen anywhere from three units of D2 to make one unit of D3 to ten units of D2 to make one unit of D3.
When your vitamin D level is low, doctors often want to give you a prescription for vitamin D. What they prescribe is called Drisdol, and it’s D2. They prescribe it in 50,000 IU soft gels, those little things that look like footballs and have oil inside.
OK. So your D is low and they give you 50,000 IU D2 and usually tell you to take it once a week. That’s not enough if your level is really low – and if your doc is prescribing vitamin D, it’s usually because it’s very, very low.
If it takes three units of D2 to make one unit of D3 in your body and you take 50,000 IU of D2, you’re really only getting about 16,666 IU of vitamin D. If it takes ten units of D2 to make one unit of D3, you’re really only getting about 5000 IU of vitamin D.
Now, keep in mind that recent research suggests that folks that have normal levels of vitamin D need 1000 – 2000 IU per day just to maintain their levels. If you needed 7000 – 14,000 IU per week just to maintain your level, do you think 5000 – 16,666 IU once a week is going to bring your level up? Not likely.
You cannot get D3 by prescription. It is only available over the counter. Even if your doc knows the difference between D2 and D3 and writes a prescription for D3, the pharmacist will give you D2. That’s because there is no D3 available by prescription and legally pharmacists are allowed to make certain substitutions. You have to get your D3 over the counter. If you just need a small, 5000 IU or less, you can find it in most pharmacies. If you need a large dose, 10,000 IU or 25,000 IU or 50,000 IU, you’ll have to order it online.
Linus Pauling Institute. http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/. Vitamin D.
Weight Loss Surgery Vitagarten. http://wlsvitagarten.com/2010/03/22/scripted-d-fail/#more-1145. Scripted D Fail.