Inclusion criteria: 1) Subject has a plasma copper level which is 80 - 155 μg/dL for women and 70 - 140 µg/dL for men, and/or ceruloplasmin activity above 62 units/L-1; 2) subject is of normal weight, BMI between 20 - 30 kg/m2, 3) subject is at least 18 but not more than 65 years of age; and 4) subject has signed an informed consent.