I'm guessing you mean "minimal amounts" because B12 doses/levels are measured in micrograms. In fact a vegan diet provides no natural B12 (see note below). This

I'm guessing you mean "minimal amounts" because B12 doses/levels are measured in micrograms. In fact a vegan diet provides no natural B12 (see note below). This is a serious gap that must be addressed by supplementation/fortification. Supplements have challenges too (and in fact many studies show supplements to be of little value). In order to attain sufficient B12 via supplements, a person needs to consume many times the RDA value. For example, only 10 mcg of a 500 mcg oral supplement is absorbed by healthy people. So while technically you may need minimal amounts of B12, it remains an essential vitamin. Getting it in a format which is both absorbable and bioavailable is not trivial and serves as a clue that human physiology evolved in an ecosystem which, to varying degrees, involved eating animals. Note: For now I'll set aside probable/common deficiencies among vegans/vegetarians in B6, heme iron, the vitamins A, D3, K2, micronutrients and fatty acids DHA, CLA, Carnatine, Carnosine, Taurine, Creatine and others. In fairness, a western/standard american diet can also score poorly in many nutrients.