I got blood work done a week ago (I am not on Soylent yet) and, while overall very good, I was low in vitamin D (I’m at 22ng/mL, 40ng/mL is optimal). I did some research into which supplement I should take, and found that it is important to take D3 if you can. See this link for a start. The differences between D2 and D3 are pretty significant: Both will prevent rickets, but D3 is more shelf stable (=predictable dose), is less likely to have toxicity issues, and binds to our tissues better, thus giving more benefit for the same dosage.
Since I hope to switch to Soylent soon, I checked soylent, and I see it has D2. I assume this is done to placate the vegans (D3 is manufactured from wool grease, D2 is made from mushrooms). The link I gave above specifically says that for vegans D2 is an acceptable substitute, but for everybody else D3 should be used. This is frustrating, because when I get soylent, I’ll be getting the worse form of the vitamin. Already Soylent will skip sending the fish oil to vegans, hopefully in the future the vitamin D supplement will be in the fish oil instead of in the main product. Has anybody official discussed the selection of D2 vs. D3?