Vegans are at risk of vitamin B12 deficiency so it is advisable to take a supplement, and we recommend a liquid or lozenge as B12 is much more absorbable in those forms.
Iron is also worth paying attention to especially for women of childbearing age. Protein powders will increase the protein content of the diet for vegans if they feel they are struggling to eat enough protein. Vegan omega 3 supplements can also fill the gap left by not eating oily fish. Calcium can also be lacking in a vegan diet.