Vitamin B12 exists naturally in milk at a concentration of 1 nanogram / mL (range: 0.3 to 3 ng / mL). Maternal supplementation with cyanocobalamin barely increases milk levels in well-nourished women (Sandberg 1981), but it does improve the levels in women of low socioeconomic status (Sneed 1981). The concentration in colostrum is up to 28 times higher than that of mature milk.The daily requirements for Vitamin B12 are 2.4 micrograms and increase to 2.8 micrograms daily during breastfeeding. Foods rich in vitamin B12 are meat, offal, eggs, dairy products, salmon, sardines, clams and fortified cereals. With a varied and balanced diet no vitamin supplements are needed, but B12 deficiency has been observed in the plasma and milk of women with strict vegetarian diets (vegans), malabsorptive diseases (eg, Crohn's disease, celiac disease), bariatric surgery, poor nutritional status, pernicious anemia, low socio-economic status and in cases of natural disasters or wars. There are numerous publications showing that infants of these mothers are at high risk of disease due to vitamin B12 deficiency, which can lead to anemia, stunting and psychomotor retardation. "Flash pasteurization" applied to breast milk of mothers who are HIV+ does not decrease vitamin B12 concentration. American Academy of Pediatrics: medication usually compatible with breastfeeding (AAP 2001).