days in 1 of 200 to 400 unsupplemented newborns. The late-onset form occurs around 1 month of age in 1 of 1,000 to 2,000 unsupplemented newborns. Late-onset hemorrhagic disease of the newborn is a devastating, often fatal disease (Gleason and Kerr, 1989). Both forms occur more often in unsupplemented breastfed than formula-fed infants.
Although maternal supplementation with vitamin K in the last weeks of pregnancy (Owen et al., 1967) or unusually high milk intakes (>500 ml) during the first 3 days of postnatal life (Motohara et al., 1989) may reduce the risk of hemorrhagic disease of the newborn, the most dependable method of preventing this serious disorder is to inject the infant with 0.5 to 1.0 mg of vitamin K at birth or to give an oral 1.0- to 2.0-mg dose, as recommended by the American Academy of Pediatrics (Committee on Nutrition, 1985) and required by many states.
Full-term infants of adequately nourished women are born with a total body vitamin B12 content of 30 to 40 µg (FAO, 1988). Assuming that 0.10 µg/day is required during infancy (FAO, 1988), these stores would supply an infant's needs for approximately 8 months. The 0.4 µg of vitamin B12 per day usually provided by human milk to the exclusively breastfed infant provides for ample accumulation of stores (FAO, 1988; NRC, 1989). Vitamin B12 concentrations in milk, and thus the infant's intake of this vitamin, are dependent on the mother's B12 intake and stores.
Breastfed infants born to women who eat little or no animal foods are at risk for developing vitamin B12 deficiency. In a study of six vitamin B12-deficient, exclusively breastfed infants in India, vitamin B12 concentrations in their mother's milk ranged from 0.03 to 0.07 µg/liter (Jadhav et al., 1962). Vitamin B12 deficiency has also been found in breastfed infants of complete vegetarian mothers in industrialized countries (Close, 1983; Davis et al., 1981; Gambon et al., 1986; Higgenbottom et al., 1978; Rendle-Short et al., 1979; Sklar, 1986). Urinary methylmalonic acid (UMMA) concentrations of the breastfed infants of omnivorous mothers were significantly lower (p = .05) than those of infants of complete vegetarians; maternal serum B12 concentrations were negatively associated with maternal UMMA (p = .003) and infant UMMA (p < .001) levels (Specker et al., 1988). In general, the deficiency syndrome is usually not clinically apparent until the latter half of infancy. An important finding is that breastfed infants may develop clinical signs of vitamin B12 deficiency before their mothers do (Lampkin and Saunders, 1969; McPhee et al., 1988).
For infants of mothers eating a mixed diet that includes animal foods, human milk is a generous source of vitamin B12; it provides for the infant's needs