65Copper absorption by women fed intrinsically and extrinsically labeled goose meat, goose liver, peanut butter and sunflower butter.

Absorption of stable 65Cu incorporated intrinsically or extrinsically into foods was studied in women fed a diet marginal in Cu content. Isotopic enrichment was 73.1 +/- 1.0 atom percent 65Cu in goose breast meat, 74.9 +/- 0.5 atom percent in goose liver, and 55-69.5 atom percent in two crops of peanuts. Seven women were fed a basal diet containing 1.25 mg Cu/d. At 4-wk intervals, they were fed test meals over a 3-d period; each set of meals contained one of the labeled test foods in amounts with similar copper content. Absorption of 65Cu from intrinsically labeled liver was (mean +/- SD) 65 +/- 4%; extrinsic liver, 65 +/- 10%; E/I = 1.00 +/- 0.16. 65Cu absorption from intrinsically labeled goose breast meat was 54 +/- 6%; extrinsic meat, 52 +/- 10%; E/I = 0.97 +/- 0.18. 65Cu absorption from intrinsically labeled peanut butter was 58 +/- 15%; extrinsic peanut butter, 54 +/- 10%; E/I = 0.93 +/- 0.11. 65Cu absorption from extrinsically labeled sunflower butter was 50 +/- 2%. There were no differences in absorption of intrinsic and extrinsic Cu from these foods. Absorption of Cu was significantly higher from goose liver than from goose meat or sunflower butter (P less than 0.05). With a dietary intake of 1.25 +/- 0.20 mg Cu/d, Cu balance, exclusive of surface losses, was essentially zero (0.01 +/- 0.13 mg/d) in the seven subjects.