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Vitamin D2 vs D3: Which is Better?

Rarely do I cover two studies on the same day, but today I've got 2 interesting vitamin D studies to share with you. Click HERE to read the other.

"Vitamin D" refers to two biologically inactive precursors: D3 (cholecalciferol) and D2 (ergocalciferol). Both precursors are transformed in the liver and kidneys into 25-hydroxyvitamin D (25(OH)D, the non-active storage form, and the compound measured to assess vitamin D status).  25(OH)D is further converted to 1,25-dihydroxyvitamin D (1,25(OH)2D, the biologically active form) in a process that's tightly controlled by the body.

Although many researchers and experts agree that many people are vitamin D deficient and need supplementation, there remains a big question mark as to the most effective form.

Previous studies have reported that the D3 form is more potent than D2, with one study reporting that D3 was 87% more potent than D2. Recently, a systematic review and meta-analysis came to a similar conclusion--that that D3 was better than D2.

Now this new study further confirms these earlier findings. Researchers recruited 95 participants (aged 18 - 50) and divided them into 3 groups: placebo, 1000 IU/day of vitamin D2, and 1000 IU/day of D3. The intervention was carried out for 25 weeks starting at the end of summer.

What the results showed were surprising. They found that 1000 IU/day of vitamin D3 maintained 25(OH)D levels during winter months, whereas 25(OH)D levels decreased with 1000 IU/day of vitamin D2.

“These findings contribute to the accumulating evidence that vitamin D3 and vitamin D2 have different pharmacokinetic profiles for serum 25(OH)D,” wrote the researchers. “As a result, care should be taken to distinguish the form of vitamin D used for both clinical studies and therapeutic use, particularly given that the dose employed in the present study is commonly used in over-the-counter dietary supplements.

Source: Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months

Other posts on vitamin D:

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  1. I'm a vegan and only use D2. What does this mean for me?
    Is this the final word, or just a piece of the puzzle?

    1. Unfortunately, with 99% of the D3 on the market being derived from lanolin (sheep's wool), it seems to be off-limits for most vegans. I say "most" vegans because I am aware of some who are not as strict, so I guess it really depends on your shade of veganism.

      Personally, I believe humans are meant to eat meat; however, we just eat WAY too much. Evolving as hunters and gatherers (assuming you believe in the predominant theory of evolution), it makes sense that gathering plants to eat was much easier and readily available than chasing down some animal. Logically, our physiology and biochemistry evolved to be based on a predominantly vegetarian cuisine, but not exclusively.

      I also understand that in a society where exploitation of animals has reached extremes, combating that must take the opposite extreme--thus veganism--it's just not my cup of tea.

      So going back to your question, for you, the best solution is likely a mixture of significant "smart" sun exposure, with modest amounts of supplemental D2.


      Aside: I take a very metaphysical approach to understanding the world we live in. In my view, plants also have a consciousness, just as animals do. I could never take a vegan-like approach to food because I'd need to cut out all living things. Yup, I'm koo-koo.

    2. I don't know any vegan who knowingly consumes D3, but I'm sure they exist.

      What do you mean by "assuming you believe in the predominant theory of evolution"
      Do you believe in evolution?

    3. I believe in evolution, but not exactly in the same sense as the prevailing Darwinism theory. I lean towards a "guided evolution" theory, but that's my personal belief, and this isn't the ideal forum to discuss this. I really want to focus on nutrition and health here. Thanks for understanding.

    4. Oh boy... the intricacies of a vegan lifestyle.

  2. Hi Dr. Know,
    Fantastic blog. I participated in a training session of yours recently. I'm definitely a layperson when it comes to this, but I thought I would pass this pdf document along to you as you might appreciate it with regards to information pertaining to calcium deposits. Thank you very much, take care. -Hannah (Hamilton, ON) http://www.realrawfood.com/sites/default/files/article/Fulvic%20Acid%20Report.pdf

    1. Thanks Hannah! I look forward to reading the article. Stay healthy!


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