Bioavailability of zinc derived from beer and the effect of low dietary zinc intake on skeletal muscle zinc concentration

Abstract The bioavailability of zinc from freeze-dried cooked beef was determined using log total tibia zinc and body weight gain as the response criteria. Control diets consisted of different levels of zinc carbonate added to an egg-white protein source. Experimental diets were made by substituting various levels of freeze-dried beef as the zinc source. All diets were isocaloric and isonitrogenous. Zinc in the control diets was utilized as effectively as zinc in the experimental diets. The relative biological value (RBV) of zinc (ZnCO 3 =100) in the experimental diet was 103 for 22-day weight gain, and 102 for total tibia zinc. These results indicate that zinc from cooked beef does not have an increased bioavailability over inorganic zinc added to an egg-white protein diet. Because a, large percentage of the total zinc in an animal is found in skeletal muscle, the content of zinc in two types of skeletal muscle was determined from animals fed different levels of dietary zinc. Animals consuming diets with zinc concentrations below their requirement had depressed growth rates; however, no significant differences were found in the zinc concentrations of either the soleus or plantaris muscle. The average zinc content of the soleus muscle (slow twitch oxidative fiber type) was 69 ppm and the plantaris muscle (fast twitch oxidative fiber type) was 15 ppm. These results indicate that the concentration of zinc in skeletal muscle is not significantly reduced in animals whose growth is restricted by low dietary zinc levels.