News to me.  Has this woman had a second opinion?.Could she be
reacting to another substance in foods/supplents?    Vitamin C is an
essential nutrient.  Without vitamin C intake the "natural level"
would be a deficiency.  (Scurvy)    Although milk levels of C are
higher than plasma levals (Nutrition During Lactation, IOM).  If
the plasma levels are very low, the breastmilk would be low too.
This could be addressed in the infant with a C supplement (NOT over
RDA, and best to involve the infant's pediatrician) -- although would
likely contribute to mother becoming deficient more quickly.  (RDA,
10th edition reports one study that showed deficiency symptoms
developing in as short a time as 24 days. The study subject weren't
lactating.  RDA is set at 60 mg/day for women, and 95 mg/day for
lactating women--first 6 mo.)  I would also be very concerned about
mother's  intake of other nutrients.