ABSTRACT
Proteins and alpha-amino acids form unionized copper complexes and thereby retard the copper-catalyzed oxidation of ascorbic acid, as first reported by Barron et al. who studied the effects of ovalbumin and glycine on the oxygen consumption of ascorbic acid in the presence of copper. Comparing diets of equal protein content fed to guinea pigs receiving 25 mg of ascorbic acid daily, he found that a casein-fed group had higher tissue ascorbic acid levels than a group of wheat gluten-fed animals. However, similar experiments on guinea pigs receiving only 2 mg of ascorbic acid a day showed all groups to have low tissue ascorbate levels and did not demonstrate the same effect of protein quality. Aldashev at the Institute of Nutrition at Alma-Ata in the U.S.S.R., studied the effects of the quality of dietary protein on the tissue ascorbic acid levels of guinea pigs.
