Preference for glucose in Zn-deficient rats selecting from glucose and fructose diets

Glucose and fructose selection patters of rats were analyzed for 28 d by a 2-choice selection in either Zn-adequate or Zn-deficient status. In this paper, we describe the following serial studies: (1) For the first 24 h, rats fed a Zn-deficient diet preferred a fructose-diet compared with a glucose-diet. On and after the third day, rats fed both Zn-adequate and Zn-deficient diets preferred the glucose-diet. (2) Throughout the experimental period, many of the rats fed a Zn-adequate and Zn-deficient diet continuously selected one diet. (3) Some of the rats fed a Zn-adequate and Zn-deficient diet suddenly changed preference for the glucose-diet or the fructose-diet. (4) The sum of daily glucose- and fructose-diet intake in rats fed a Zn-deficient diet showed a characteristic variation with the cyclic period of 3.9+-0.4 d.