The effect of severe protein deficiency on serum zinc concentration of mice fed a requirement level or a very high level of dietary zinc.

The objective of the present study was to determine the effect of severe dietary protein deficiency on serum zinc concentration in weanling animals fed either a requirement level or a very high level of dietary zinc. Weanling (21-day-old) male and female CBA/J mice were randomly assigned to be fed one of four diets containing either 1.7% or approximately 18.5% protein and either 7 micrograms (predetermined requirement level) or about 200 micrograms zinc per gram of formulation. Serum zinc levels were measured after a 14-day feeding period. Dietary zinc content, over the range tested, did not influence the serum zinc level of protein deficient mice, and these animals exhibited serum zinc concentrations which were much lower than the levels found in adequately nourished mice fed the requirement level of zinc (7 micrograms/g diet). These results indicate that dietary zinc supplementation is unable to restore to normal the zinc status of severely protein-deficient animals. This may be an important factor to consider when studying the effect of protein deficiency on zinc-sensitive physiological processes.