After reading that other people put their "two cents worth" in about a
topic, I decided I would too.
I think Becky B asked about the Vegan diet and the breastfeeding mom.  I
looked it up in 3 different resources and here's what I found:

Vitamin B12 deficiency doesn't occur in breastfed infants UNLESS their
mothers are deficient in the vitamin.  Infants showing such a deficiency
respond hematologically to 0.2 mcg vitamin B12 orally.  It was reported also
that an infant exclusively breastfed by a mother with a latent pernicious
anemia developed megaloblastic anemia and neurologic abnormalities.
Natural source of this vitamin in nature is synthesis by microorganism.
It's not found in plants unless contaminated by the natural organism.  Small
amounts of B12 found in legumes and in contaminated food may be the only
diet source of B12 for Vegans.  Bacteria in knobby growth of some seaweeds
also make the vitamin.
(From Shils, Olson, & Shike - Modern Nutrition in Health and Disease)

BFing infants of Vegans are at risk of developing B12 deficiency if the
mothers intake of B12 is inadequate, since the B12 concentration in
breastmilk is dependent upon the mother's intake.  In general, the
deficiency syndrom is usually not clinically apparent until the latter half
of infancy.  Infants may show clinical signs of B12 deficiency before the
mother does
(From Institute of Medicine - Nutrition during Lactation)

2-1/2 x 2-3/4 x 1" piece of tofu contains 0 mcg of B12 according to Laurel's
Kitchen - a cookbook for vegetarians.  The author further states that
Vegan's diet must be supplemented with B12 and she gives a recipe for
fortified soy milk

This may all be a mute point if the mom is already making sure her diet is
sufficient in B12.  Unfortunately, however, not all people who want to
follow a Vegan diet "read up on it" like they should.

Debbie McClurg-Hitt, RD