Some Interrelationships of Copper, Molybdenum, Zinc and Lead in the Nutrition of the Rat

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Abstract
A toxicity was produced in rats by additions of molybdenum to two different basal diets, viz., mineralized whole milk powder and rat chow. Using the milk powder diet, a study was made of the interrelationships of copper, molybdenum, zinc and lead in the nutrition of the rat. The effects of molybdenum in retarding growth and of zinc in producing an anemia were confirmed. The ability of copper to correct this effect of molybdenum on growth was not clearly defined at the mineral levels used; however, copper corrected the anemia caused by zinc, as it had in past work. Zinc did not retard the growth of rats fed these milk powder diets, but the presence of both molybdenum and zinc in any diet resulted in significantly poorer growth than was caused by the addition of only molybdenum. Lead alone had no effect on growth or hemoglobin. At the levels fed, none of the minerals affected leukocyte count. The demonstration of such relationships as these, viz., between copper and zinc, and molybdenum and zinc, and probably molybdenum and copper, emphasize the necessity for a consideration of the levels of all minerals in the diet before determining the requirements for any one. This type of study reaffirms the observation that a deficiency disease may not reflect merely a low level of a dietary essential, but an excess of one or more other nutrients which interfere with the normal metabolism of that essential dietary constituent.