How sustainable lichen-derived vitamin D3 is?

[Canastenard]

You probably already know that there's vitamin D3 commercially available that's not derived from sheep's wool, rather being extracted from some species of lichen. However, I wanted to be sure about how sustainable lichen-derived is and compare it to sheep-derived D3, as I had a gut feeling that maybe lichen isn't as D3-dense as sheep's wool, so I searched to check it.

I found the following resources:
https://vitamindwiki.com/How+vitamin+D+ ... -+Feb+2011
http://lup.lub.lu.se/search/ws/files/4763528/624375.pdf

(Yeah this article is pretty old. I guess it was already known that D3 was produced by non-animal species, but is only commercially available since more recently.)

According to the first article, one single sheep can give up to 2.8 million pills of 1,000 IUs of vitamin D3 per year (assuming one shearing per year). Based on the second article, taking the lowest amount of D3 per gram of dry weight for the sake of doing a conservative estimate, one gram of lichen contains 26,800 IUs of vitamin D3 (taking Wikipedia's values from the cholecalciferol article: https://en.wikipedia.org/wiki/Cholecalciferol of 40,000,000 IUs per gram or 40.000 per milligram), or 26.8 pills of 1,000 IUs per gram of dry lichen.

Since the amount of wool produced by sheep per year suggested by the first link is a very wide range (from 2 to 30!) I needed more information about how much a typical fleece weighs and a link I found suggested an average 7.3 pounds (http://www.sheep101.info/wool.html) so I'll assume that 7,3 pounds of sheep wool contain the equivalent of 2,800,000 pills of 1,000 IUs of vitamin D3, or about 383,560 per pound. Since one pound is equal to 453.592 grams, one pound of dry lichen would contain the equivalent of 26.8 × 453.592 pills of 1,000 IUs of vitamin D3, or 12,970 of them. If my calculations are correct, that means for the same dry weight, sheep's wool is almost 30 times more D3-dense than lichen.

Of course this is a conservative estimate taking the worst kind of lichen into account, I'm sure lichen D3 companies use more productive varieties, assuming for example 2 mg of D3 per dry matter weight you could have 80 pills by grams or about 36,290 per pound, making lichen a little more than ten times less D3-dense than sheep's wool which is at least an improvement from the conservative estimation I've detailed before.

Another concern is about how slow lichen is at growing. In my research I've found this page: http://protecnutra.com/downloads/vitashine_brochure.pdf apparently Vitashine (the first company that commercially sold vegan D3) themselves admit that lichen grows "extremely slowly" and further research suggested me that they grow as slowly as only a few millimeters a year. It might make scaling up lichen production a challenge, and is probably a big reason why vegan D3 is more expensive than wool-derived D3 besides economies of scale.

After doing that research, it looks like the main limiting factor of lichen as a D3 source might not be D3 density, which while apparently lower than in sheep's wool thus confirming my initial gut feeling is probably not the main problem but one on top of the slow growth one which seems to be the actual big deal. So I'm not really sure if we can ever make lichen the main source of vitamin D3 over sheep's wool, even by scaling up lichen production and scaling down sheep farming.

[cornivore]

Thanks for the info. My question about supplements was which ones were USP verified, because when ones that weren't got tested, they turned out to contain far less of the vitamins that they claimed to on the label. It doesn't look like many vegan supplements have a USP verification, or are otherwise independently tested in order to verify that they actually contain any vitamins.