Vitamin B12, often known as cobalamin, helps the human body perform a variety of functions, including energy production and mental clarity. Vegetarians are more likely to be deficient in Vitamin B12 because it is most easily obtained from animal products. If not treated, low vitamin B12 levels can cause symptoms ranging from weakness and fatigue to shortness of breath and neurological disorders. Knowing the best vitamin B12 sources for vegetarians might help prevent shortages.