Bluerose, longtimenosee…hope this can add to your info, (I don't know the answer to your question or your doc's council), lucidhunt

http://www.differencebetween.net/science/difference-between-vitamin-d-and-vit...


Difference Between Vitamin D and Vitamin D3

Vitamin D vs Vitamin D3
If you have been advised a series of vitamins and are wondering about their effects, here are a few facts you need to know about vitamin D. It is one of the more complex vitamins that are needed by the human body in order to grow and develop. Vitamin D is actually available in two forms, cholecalciferol and Ergocalciferol, better known as vitamin D3 and vitamin D2.

First things first. Vitamin D can be found in 2 forms. Vitamin D2 is manufactured by plants or fungus. You would include it through fortified foods such as juices, milk or cereals. However, vitamin D3 is formed when the body synthesizes sunlight on its surface. It mainly occurs through the exposure of the skin to UVA and UVB rays. Vitamin D3 can also be obtained by consuming animal products.
It is also interesting to note that since it is produced in the body, vitamin D is actually considered a hormone and not really a vitamin! Vitamin D is very important as it regulates the production of phosphorous and calcium in the body.

The Vitamin D that you purchased so willingly over the counter in the form of medication can actually be very harmful without supervision. You see, one of the forms of vitamin D, i.e. vitamin D2 is broken down by the body into different substances. Some of these substances can be very harmful for the body. Vitamin D3 is broken down by the body into a substance called calcitrol, which actually has very important cancer fighting properties.
The supplements for vitamin D may be made from either plants or animals. However, if you were looking for a vitamin D3 supplement, you would look for only those available through animal supplements. It is also available from lamb’s wool!


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Vitamin D is frequently added to a number of foods, to make them beneficial. However, if you were looking for vitamin D3 in particular, you would have to go for a pill or a liquid form. It is not very common to find it in cereals or juices.
Another important difference is that vitamin D2 has a shorter shelf life compared to vitamin D3. This decreases the potency of the vitamin if it is used as a vitamin supplement. Some researchers however feel that their efficacy is the same.
Summary:
1. Vitamin D is manufactured by both plants and animals. Vitamin D3 is particularly found on the skin of animals, as a byproduct of synthesis.
2. Vitamin D is not beneficial in all its forms. Vitamin D2, one of the forms of vitamin D can be toxic to the body. Vitamin D3 is good for the body.
3. You can get vitamin D from fortified foods or as pills. However, vitamin D3 is only available in the form of pills or in liquids. They are rarely found in foods.
4. Supplements for the two vitamins are sourced differently.
5. The D2 form of the vitamin has a shorter shelf life compared to the D3 form.

Read more: Difference Between Vitamin D and Vitamin D3 | Difference Between | Vitamin D vs Vitamin D3 http://www.differencebetween.net/science/difference-between-vitamin-d-and-vit...

If you take Vitamin D supplements vitamin D3 is supposed to be better than D2, because some studies suggesting D3 is better absorbed. But 2011 clinical guideline considered vitamin D2 to be as effective as (vitamin D3 (cholecalciferol), which is produced naturally by the skin when exposed to ultraviolet light.

http://www.vitaminsupplement.me.uk/vitamins-blog/107-vitamin-d-and-vitamin-d3...