<human>:  Is a vegan diet nutritionally adequate for humans?
<bot>: Yes, a vegan diet can be nutritionally adequate for humans if it is well-planned and includes a variety of fruits, vegetables, grains, legumes, nuts, and seeds. Adequate amounts of vitamins, such as B12 and D, as well as calcium, iron, and zinc need to be taken through supplementation or from fortified foods to ensure adequate nutrition. Additionally, vegan diets need to include healthy sources of fats and proteins to meet the body's nutritional needs.