First of all, supplements are available as Vitamin D2 (Ergocalciferol) or Vitamin D3 (Cholecalciferol). The 25-Hydroxy Vitamin D test determines the combined level of Vitamin D2 and D3. Skin of animals, including humans synthesize the D3 from the Ultra Violet B (UVB), while plants synthesize D2.
To read why we need Vitamin D, and what may cause deficiency even when you think you are getting enough sun, see my previous post here.
Vitamin D2 or D3?
For more than 70 years, D2 has been administered to children and adults to successfully increase Vitamin D level in the blood. In last few decades, some scientific studies suggested that D3 is more effective than D2 as our skin is anyway supposed to synthesize D3. However, more recent studies suggested that D2 can be as effective as D3.
I didn’t go to medical school, but my doctor didn’t have a clue either, so I had to do my own research. I haven’t come across any study or article that would suggest D2 is better than D3. Please point me to one if there is out any. Does that mean when possible take D3 instead of D2? I would like to think so.
Here is a compilation from an MD, Dr. Christensen on why D3 over D2 [Reference]:
- UVB light from the sun strikes the skin, and humans synthesize vitamin D3, so it is the most "natural" form. Human beings do not make vitamin D2, and most healthy fish contain vitamin D3.
- Vitamin D3 is the same price as vitamin D2.
- Vitamin D3 may be less toxic than D2 because higher concentrations of D2 circulate in the blood when consumed (compared to vitamin D3). It does not bind as well to the receptors in the human tissues compared to vitamin D3.
- Vitamin D3 is the more potent form of vitamin D, which is a potential benefit. For example, obesity tends to lower blood levels of vitamin D, so a more potent form is needed.
- Vitamin D3 is more stable on the shelf compared to D2, and is more likely to remain active for a longer period of time and when exposed to different conditions (temperature, humidity, and storage). This is perhaps why the amount of vitamin D2 in certain fortified food products have been significantly lower than that advertised on the label in numerous instances.
- Vitamin D3 has been the most utilized form of vitamin D in clinical trials, and there have only been a few clinical trials of vitamin D2 to prevent bone fractures in adults.
- Vitamin D3 is more effective at raising and maintaining the vitamin D blood test (again, D2 binds less tightly to the vitamin D receptors in the body; therefore, D2 does not circulate as long in the body, which means it has a shorter half-life).
Choosing the Right Supplement
- D2 and D3 are fat soluble and is best taken in a gel capsule form. So, stay away from tablets.
- D3 supplements are derived from animal base, some of D2 are plant based. So, vegans may prefer the plant based D2
- It appears that USA Food and Drug Agency (FDA) has not approved D3 yet. So, for high dose of Vitamin D, where prescription is required, you may only get D2. However, I found a few high dose D3 available without prescription too.
- Go with a brand you trust. If you are new to the vitamin world, like me, I had to do some more research.
Selecting the Product to Buy
Based on the reviews I narrowed down to the following products:
- HealthyOrigins - Got the best deal on Soap.com with free 2-day shipping and 15% discount code: ANXX6983. The shipment promptly came in the next day!
- ProHealth Vitamin D3 Extreme™
- Biotech Vitamin D3
- Now Foods Vitamin has D-2 and D-3 products
- Deva Vegan Vitamin D2
Taking the Capsule
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Check with your doctor, mine suggested to take after full meal, otherwise it can upset stomach.
