Vitamin C levels in breastmilk apparently level off at 50-60 mg/L if maternal intake is over 100
mg daily (Bates Int J Vit Nutr Res 1983;53:68-76).  When intake is below this level, an
increase in vit C is accompanied by an increase in Vit C content in breastmilk.  Maternal
supplementation, therefore, would seem not to be problematic for the infant, especially for a
short time.  Intakes of vit C over 1000 mg actually have antihistiminic and pro-oxidant effects
(this is not a typo).  Therefore, I never recommend vit C in this large of a dose for anyone.