Apparent copper absorption from a vegetarian diet

Abstract

Background: Vegetarian diets often contain more copper than do nonvegetarian diets, but observations of decreased plasma copper associated with vegetarian diets suggest that these diets have lower copper bioavailability than do nonvegetarian diets. Objective: Our objective was to determine apparent copper absorption from controlled lactoovovegetarian and nonvegetarian diets. Design: Eighteen women aged 20-43 y consumed lactoovovegetarian and nonvegetarian weighed diets for 8 wk each in a randomized, crossover design. The lactoovovegetarian and nonvegetarian diets provided 1.45 and 0.94 mg Cu, 38 and 16 g dietary fiber, and 1584 and 518 mg phytic acid, respectively, per 9.2 MJ (2200 kcal). After the women had been consuming each diet for 4 wk, their apparent copper absorption was determined by measuring the fecal excretion of the 65Cu stable isotope, extrinsically added to the entire menu as 65CUCl2. Results: Plasma copper and ceruloplasmin were not affected by diet. The efficiency of apparent copper absorption from the lactoovovegetarian diet was less (33%) than that from the nonvegetarian diet (42%) (pooled SD: 9%; P < 0.05). However, because the lactoovovegetarian diet contained ≅50% more copper, the total apparent copper absorption from the lactoovovegetarian diet (0.48 mg/d) was greater than that from the nonvegetarian diet (0.40 mg/d) (pooled SD: 0.09 mg; P < 0.05). Conclusion: Although copper was less efficiently absorbed from a vegetarian diet than from a nonvegetarian diet, total apparent copper absorption was greater from the vegetarian diet because of its greater copper content.