https://www.ncbi.nlm.nih.gov/books/NBK2 ... ddd0000221
Older balance studies suggested that the adult requirement for copper ranged from 2.0 to 2.6 mg/day, whereas later studies indicated that intakes less than 2.0 mg/day, and often not much more than 1.0 mg/day, could maintain positive copper balance (Mason, 1979).
If the true gastrointestinal absorption of copper at intakes of 1.7 to 2.0 mg is 36% (± 1.3 SEM) (Turnlund et al., 1989), then a dietary intake of 0.3 mg/day is required to replace body surface losses.
Adding this figure to the average dietary intake of 1.3 mg/day needed to replace urinary and fecal losses indicates that a total dietary copper intake of approximately 1.6 mg/day is required to maintain balance in adult men.
Many U.S. diets provide less than 1.6 mg of copper daily (Klevay, 1984).
http://lpi.oregonstate.edu/mic/minerals/copper
The RDA for copper (900 μg/day for adults) is sufficient to prevent deficiency, but the lack of clear indicators of copper nutritional status in humans makes it difficult to determine the level of copper intake most likely to promote optimum health or prevent chronic disease. A varied diet should provide enough copper for most people. For those who are concerned that their diet may not provide adequate copper, a multivitamin/mineral supplement will generally provide at least the RDA for copper.
Because aging has not been associated with significant changes in the requirement for copper, our recommendation for older adults is the same as that for adults 50 and younger.
