[ksala_]

I don't know what D12 is (and I haven't been able to find anything from some online searches), but you can find the sources of their vitamins (and other components) in https://eu.huel.com/pages/about-the-vitamins-minerals-in-hue...

If you're talking about B12, they use Cyanocobalamin which is produced by bacterias - Wikipedia page: https://en.wikipedia.org/wiki/Cyanocobalamin#Production.