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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Healthy Body Weight Research » Research » Publications at this Location » Publication #117822

Title: APPARENT COPPER ABSORPTION FROM A VEGETARIAN DIET

Author
item Hunt, Janet
item VANDERPOOL, RICHARD A

Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2001
Publication Date: 12/1/2001
Citation: Hunt, J.R., Vanderpool, R.A. 2001. Apparent copper absorption from a vegetarian diet. American Journal of Clinical Nutrition. 74:803-807.

Interpretive Summary: Vegetarian diets often contain more copper than omnivorous diets, but seem to reduce the amount of copper in blood plasma. This study measured copper absorption by healthy adult women, who consumed controlled lactoovovegetarian and nonvegetarian diets for 8 wk each. After 8 wk on the vegetarian diet, plasma copper was only slightly reduced, a difference which was not statistically significant. Copper absorption was somewhat less efficient from the vegetarian diet; while the vegetarian diet contained 50% more copper, only 20% more copper was absorbed. Together with previous research, these results suggest that vegetarian diets may reduce plasma copper slightly, but this reduction is not caused by reduced dietary copper absorption. A diet containing generous amount of plant foods provides more copper that is effectively absorbed and retained by the body.

Technical Abstract: Vegetarian diets often contain more copper than omnivorous diets, but the reduced plasma copper observed in two longitudinal studies suggests that the copper may be less bioavailable from these diets. Copper absorption from controlled lactoovovegetarian (V) and nonvegetarian (N) diets was investigated in 17 healthy adult women who consumed both weighed diets for 8 wk each in a randomized, cross-over design. The V and N diets provided, respectively, (analyzed) 1.45 and 0.94 mg copper, 8.7 and 10.5 mg zinc, and (calculated) 12 and 16% protein, 38 and 16 g dietary fiber, and 1584 and 518 mg phytic acid per 2200 kcal (energy and other constituents were adjusted for body size). Apparent copper absorption was determined after 4 wk on each diet by extrinsically labeling the entire 2-d cycle menu with 65**CuCl2 stable isotope and measuring fecal excretion of isotope. The V diet reduced plasma copper concentration and ceruloplasmin activity nearly as much (~5-6%) as observed previously (~7-8%) with the same diets (Hunt et al., AJCN 67:421, 1998). But in contrast with that study, these changes were not statistically significant in the present study. The efficiency of copper absorption from the V diet was less (33%) than from the N diet (42%)(pooled SD 9%; p<0.01). However, because the V diet contained ~50% more copper, more copper was absorbed from the V (0.48 mg/d) than from the N diet (0.40 mg/d)(pooled SD 0.09 mg; p<0.05). Together with previous findings, these results suggest that vegetarian diets reduce plasma copper slightly, but this reduction is not caused by reduced dietary copper absorption.