Effect of high dietary glutamic acid on the excretion of 35S-thiamin in kittens

Six kittens individually housed in stainless steel metabolism cages were fed a control diet containing 3% glutamic acid (Glu) for 2 weeks and then subsequently for 12 weeks were fed a 12% Glu diet. All diets contained 4.4 mg thiamin/kg diet. The 12% Glu diet significantly depressed weight gain during the first 6 weeks and food intake during the 3rd and 4th weeks of dietary regimen as compared to the control period. Plasma levels of Glu increased with the duration of the 12% dietary regimen. On days 0, 14, 28 and 42, the kittens were given a 4 g meal containing 10 μCi of ³⁵S-thiamine. Although the mean excretion of isotope in the feces, calculated as a percentage of the ingested dose, was about 25% greater in the first 2 weeks of the 12% Glu dietary regimen than the control period, the difference was not significant. Urinary excretory rate of ³⁵S-thiamin was depressed during the first 4 weeks of the 12% regimen. When exponential relationships were fitted to the excretion data, the coefficients for the first and second 2-week intervals of the 12% Glu dietary regimen were -0.177 and 0-167, respectively, compared to -0.199 and -0.212 obtained for the control period and the third 2-week interval of the high Glu dietary regimen, respectively.