Vitamin D2 vs. Vitamin D3

This is just a quick update to my previous post about Dr. Andrew Weil's article on becoming vegan, where he recomends taking Vitamin D3, which is almost always derived from animals (which, of course, means it's generally not vegan). In his article, he didn't mention Vitamin D2, which is usually derived from non-animal ingredients and is the form that tends to be used in vegan vitamins.

According to this recent study, although it was once thought that Vitamin D2 was less effective than D3, both forms are equally effective. So, there's no need for an animal-derived supplement.

Andrew Weil and animal-derived supplements for vegans

So, I just read an article by Dr. Andrew Weil, the portly quasi-Santa-lookalike nutritional guru. It's called ''Becoming a Vegan''. In it, Weil perpetuates some iffy information that more or less amounts to saying that you cannot thrive on a completely vegan diet. He brings up two instances where, in his opinion, animal products are necessary. First, with regards to Vitamin D, he writes the following:

I recommend a daily supplement of 1,000 IU of vitamin D3 -- cholecalciferol -- for everyone (vegan or not).

He asserts that your body can produce enough Vitamin D from exposure to sunlight, but states that most people don't go outside enough, hence the need for a supplement. The thing is that cholecalciferol (D3) is generally derived from sheep's wool -- definitely not vegan. Oddly, he makes no mention at all of Vitamin D2, which isn't derived from animals and which is commonly used in vegan vitamins.

Then, with reference to omega-3s, he writes:

Be aware that the vegetarian sources of omega-3s are not as good as oily fish. Consider taking a fish oil supplement or, at least, an algae-derived supplement of DHA.

Why would someone write an article about becoming a vegan and recommend taking an animal-based supplement as an option? The article seems mistitled. It would be more accurate for it to maybe refer to issues Weil finds inherent in a vegan diet; it's not about how to adopt a vegan diet if he suggests -- twice -- consuming animal products as necessary? I mean, is the definition of veganism now purportedly open to tweaking. too? (OK, my crankiness is showing, I'll admit...)

According to the Physician's Committee for Responsible Medicine (PCRM), fish-derived sources of omega-3 are at the very least unnecessary, and on top of that, that

omega-3s in fish oils are highly unstable molecules that tend to decompose and, in the process, unleash dangerous free radicals. Research has shown that omega-3s are found in a more stable form in vegetables, fruits, and beans. (See referenced text here.)

With regards to Vitamin D, the Vegan Society has information on animal-free ways to meet your daily requirement. The Vegetarian Resource Group (VRG) has a blurb on the differences between Vitamin D2 and D3. Both are used to fortify milk and other dairy products and Vitamin D3 isn't always animal-derived (but usually is). I haven't seen anything to indicate that one form is superior to the other, really. I'll see if I can dig up some more information about this in my copy of Joanne Stepaniak's Vegan Sourcebook, but it seems to me that Dr. Weil's opinion left some pretty serious blanks to fill and that since he writes as an authority on nutrition, most reading his article wouldn't even think to second-guess what he says. Thankfully, groups like PCRM and VRG exist to set the record straight.