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Journal of Nutrition Vol. 111 No. 11 November 1981, pp. 1964-1968
Copyright © 1981 by American Society for Nutrition
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A Postabsorption Effect of L-Ascorbic Acid on Copper Metabolism in Chicks1,2,

Robert A. Disilvestro and Edward D. Harris

Department of Biochemistry and Biophysics and the Texas Agricultural Experiment Station, Texas A & M University, College Station, TX 77843

We have studied the effects of L-ascorbic acid (vitamin C) on copper metabolism using copper-deficient chicks and the activation of lysyl oxidase, a copper-dependent enzyme, to assess bioavailability of copper. When administered intraperitoneally with (or 75 minutes before) CuSO4, L-ascorbate significantly impaired the effectiveness of copper to restore lysyl oxidase activity in deficient chicks. L-ascorbate given 75 minutes after CuSO4 (i.e., in the post-absorption period), however, produced a substantial increase in copper-induced enzyme activation. L-ascorbate by itself showed no direct stimulating effect in deficient chicks. When the L-ascorbate was given to chicks that had received adequate dietary copper, there was a strong rise in ceruloplasmin and a slight, but significant increase in lysyl oxidase. An increase in ceruloplasmin in response to copper was also seen in deficient chicks and L-ascorbate also augmented that increase. Substituting D-isoascorbic acid for L-ascorbic acid eliminated postabsorption stimulation. The studies confirm the antagonistic properties of L-ascorbic acid on copper metabolism, but they also reveal possible sterospecific postabsorption roles for L-ascorbate in the metabolism of copper.

KEY WORDS: • ascorbic acid • Cu metabolism • lysyl oxidase ceruloplasmin

1 Funding provided by USPHS grant AM-26604 from NIAMDD.

2 A preliminary account of this work has appeared (Fed. Proc. 40, 950 [1981]).

Manuscript received 28 April 1981.




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