After two years, women who got less than the recommended dietary allowance (RDA) for copper, magnesium or zinc had poorer bone health than women who got at least the minimum RDA. For zinc, women who got between the minimum RDA of 8 mg per day and up to 20 mg per day (2.5 times the RDA) had healthier bones than women who got more or less zinc. For women, aged 50-70 years, the RDA for copper is 0.9 mg, for magnesium is 320 mg, and for zinc is 8 mg per day.