The subject of vegan diets is covered in Lawrence's 1994 text, pp.301-2.
There is a risk of decreased absorption of minerals such as iron, zinc
and calcium due to increased dietary phytates and fiber.  Careful use of
complementary proteins is stressed to avoid deficiencies in essential
proteins.  Vitamin D is a problem in dark-skinned mothers in climates
with little sunshine (we've seen cases of rickets in New Jersey among
babies of Black Muslim mothers who eat vegetarian diets without milk
products, nurse exclusively for 2 years, and cover themselves and their
babies, receiving minimal sun exposure).  The other potential deficiency
in this diet includes Vitamin B12 and riboflavin.  Hope this helps.
Alicia.  [log in to unmask]