Since one of the reasons that I follow a vegan diet for is the relatively lower ecological impact that it has on the planet, I was wondering whether there are some studies looking into the ecological impact of producing vegan supplements. Are there any challenges for the vitamin supplementation to scale if a major part of planet's population was to switch to plant-based diet?
For the purpose of this question I am looking mainly at vitamin D3 and B12, produced in a vegan manner.