There are five forms of Vitamin D - D1, D2, D3, D4 and D5. The most important forms used by the body are D2 and D3. Supplemental Vitamin D comes in either of these two forms:
- Ergocalciferol (Vitamin D2)
- Cholecalciferol (Vitamin D3)
The notion that Vitamin D2 and D3 were equivalent to each other was based on historical studies of rickets prevention in children which lead it to become known simply as Vitamin D.
Where do you get Vitamin D from?
Vitamin D is synthesised in the skin as Vitamin D3 (cholecalciferol). It is obtained from dietary sources or supplements in either Vitamin D3 or Vitamin D2 (ergocalciferol) form.
Plant sources provide you with Vitamin D2. The more beneficial Vitamin D3 is the form naturally produced by your body and can only be obtained via animal/fish based sources such as:
- Oily fish e.g. salmon, mackerel, tuna and sardines
- Egg yolk
- Unpasteurised milk
- Some yoghurts
Clinical Trials have proved Vitamin D3 to be superior to Vitamin D2
A 2011 Cochrane Database study highlighted the significant differences between the two and examined mortality rates for people who supplemented their diets with Vitamin D2, versus those who did so with Vitamin D3. The analysis of 50 randomised controlled trials, which included almost 100,000 participants, showed a 6% relative risk reduction among those who used D3, and a 2% relative risk increase among those who used D2.
Your body deals with the different types very differently
According to recent research, Vitamin D3 is approximately 85% better in raising and maintaining Vitamin D concentrations in the body and produces 200-300% greater storage of Vitamin D than Vitamin D2.
With either form your body must convert it into a more active form, and Vitamin D3 is converted 500 percent faster than Vitamin D2.
Vitamin D2 has a shorter shelf life and it binds poorly with proteins in your blood which further hinders its effectiveness.
If it just says "Vitamin D" how do you know what you are taking?
If your supplement packaging just says Vitamin D with no number after the letter D, look at the ingredients list and check to see if it says from ergocalciferol (which is D2) or cholecalciferol (which is D3).
Milk has long been known as a good source of Calcium, Magnesium and Vitamins A, C, D and E, however milk in the UK contains very little Vitamin D. In the USA milk is fortified with Vitamin D but we have not followed suit with this practice yet. Our fortified foods include margarine (which is required by law to contain Vitamin D), some yoghurts and breakfast cereals.