Look out for B12 added to things such as soya/oat (etc.) "milks." Alternatively, don't be a vegan... Millions of acres of land on this planet can support animal husbandry but not arable farming, in highlands, on steep or rocky slopes or in areas with seasonal droughts or poor or unirrigated soils. Millions of children in developing countries can't afford fancy supplements to compensate for what they wouldn't get from a vegan diet, and without milk, for example, they would be in dire straits. Subsistence farmers in those countries can't afford expensive chemical fertilisers and rely on animal manure to keep their land in good heart and to feed their crops. Veganism must be a personal choice to be kept quiet about, free from evangelism. I know you weren't doing that. I'm just sayin'.

An interesting thought is that not a single human being has ever started life as a vegan.