Vitamin D2 vs D3


Is anyone else concerned about the use of vitamin D2 vs D3? I get that D2 is vegan and D3 isn’t, but the scientific consensus seems to be that D3 might be better than D2.
For instance…

There are also some reports than D2+D3 is worse than just D3 alone.

For the record, I’m not against artificial sweeteners and flavorings, or anything like that. I would prefer a vegan vs non-vegan product. But based on my reading, it seems like there might actually be benefit to D3 vs D3.


Wait, so supplementing, say, 1000ug of D2 and another 1000ug of D3 is WORSE than just 1000ug of D3? or 2000ug?

If the former, I doubt the science. If the latter, I’m still not overly concerned.


Here is another paper. I will try and find the one I read about D2 inhibition of D3. It isn’t that hard to see how D2 could inhibit D3 utilization. Whereas D3 is the endogenous species, D2 can still activate the same pathways, but perhaps less efficiently. In this way, it could act as an inhibitor of D3. An important fact is that, from the paper above, a D2 activity seems to saturate at a lower final activity than D3, which could be quite biologically important. Also, we are just starting to understand the effect of vitamin D on things other than ricketts, such as mood. The activity of D3 vs D2 could be different there.

I’m not saying this is the case, and I will look for more studies, but the scientific consensus seems to be that D3 is a better vitamin. It can probably be overcome by additional D3 supplementation - but I would rather not have to take an additional supplement. Small issue, but worth discussing.

Also, your shark example is off the mark. A 50% increase in shark attacks doesn’t matter because in both cases you chances of getting eaten by a shark are incredibly small, thus unlikely to have an impact on your life. However, a 50% increase in vitamins (or 20% as suggested in the linked paper) could well put your from deficiency to proficiency.


There are vegan D3 sources, they come from mushrooms exposed to UV light.


Hi Sam, that is how you make D2, not D3. D2 and D3 are very similar, except D3 is made from the animal molecule, cholesterol, while D2 is made from the fungal molecule, ergosterol. D2 is made by exposing mushrooms to UV light, whereas D3 is made by extracting cholesterol from wool and exposing it to UV light.


I agree that it’s a strike against the official product, though not a huge one (I use D3 only in my DIY formulas and supplements).

Based on my review of the evidence, I think it’s actually more objectionable that they’re using K1 to the exclusion of any form of K2 (I supplement with K2 MK-4).


I’ll look into K2. Do you have any suggested references?


Take a look at “Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study.”

Those with the highest third of dietary vitamin K2 intakes in the study were 52 percent less likely to develop severe calcification of the arteries, 41 percent less likely to develop heart disease, and 57 percent less likely to die from it. By contrast, intake of vitamin K1 had no effect on cardiovascular disease outcomes.

This finding alone raises a major red flag contradicting the assumption that humans have the capacity to convert K1 to K2 at levels adequate for optimal health.

Dietary K2 is also at least three times more effective than K1 at activating proteins related to skeletal metabolism (see Schurgers et al., 2007)

On top of this, data from the EPIC-Heidelberg study suggest that dietary K2 reduces the risk of prostate cancer by 35 percent (whereas K1 has no effect).

All of these data points are inconsistent with the notion that K2 is extraneous, or fully synthesized as needed.

As far as my own health is concerned, I agree with Chris Kessler that K2 deserves to be regarded as an essential nutrient in its own right. At minimum, I think it’s a good idea to have both K1 and K2 contributing to the dietary requirement for “K.”


It appears I was mislead:
There are D3 sources that claim be be vegan and from mushrooms but they are produced by feeding the mushrooms lanolin from sheep, so saying it’s vegan is rather debatable.“vegan”-vitamin-d3-from-mushrooms/

However, there is one vegan D3 source produced from lichen

Also; kudos for the name. What's your least favourite country?


It’s not a 50% increase in vitamins I’m talking about, it’s the “increase in risk” from moving to a combined supplementation of D2 and D3 at the same total weight of vitamins.


Yikes, I hadn’t read up on K2 before. I eat eggs on most days, but with soylent for breakfast I would be missing out on it. I already take choline supplements on days when I skip eggs, I guess I’ll add K2 to the list. Thanks for the info.