The concentration of copper in cow milk has been reported to range from 60 to 90 μg/L (Fransson and Lonnerdal, 1983) which is lower than that reported for human milk (Table 7-1). Copper is bound to the fat fraction (15 percent) in cow milk with the remaining bound to casein (King et al., 1959). It has been reported that copper absorption in infants fed human milk is greater than in infants fed a cow milk-based formula (Dorner et al., 1989; Johnson and Canfield, 1989). Copper deficiency has been observed in infants fed cow milk (Cordano et al., 1964; Levy et al., 1985). Dorner and coworkers (1989) showed that 20 percent of children were in negative balance when fed unsupplemented formula, whereas all children were in positive balance when fed either human milk or supplemented formula.

No data are available on which to base the Estimated Average Requirement (EAR) for copper for children or adolescents. In the absence of additional information, EARs and Recommended Dietary Allowances (RDAs) for children and adolescents have been estimated by using the method described in Chapter 2, which extrapolates from the adult EAR. Although there are no studies available to indicate that the copper requirement is associated with energy expenditure, metabolic weight (kg^0.75) was used for extrapolating because of the structural and functional role of copper in a number of enzymes and because using metabolic weight yields an EAR that is higher than when total body weight is used.