The effect of vitamin B-6 deficiency on copper, zinc and iron balance in the rat.

Abstract

In order to address the contradictory reports on the rat trace element status during a vitamin 8-6 deficiency, Zn, Cu and Fe balance was assessed over 8 weeks in 3 groups of young male rats. Group 1 was the control group fed on a diet supplemented with 3,5 mg/kg of vitamin B-6. Group 2 was the marginally deficient group, fed a diet supplemented with 1,75 mg/kg of vitamin B-6 and Group 3 was the totally deficient group without any vitamin 8-6 in the diet. Diet, urine and fecal samples were analysed to determine the mean daily Zn, Cu and Fe balance for each group during each week of the study. Urinary xanthurenic acid (XA), plasma pyridoxal (PL), and plasma pyridoxal 5' -phosphate (PLP) were also analysed in order to determine the vitamin 8-6 nutritional status of each animal group. The totally deficient Group 3 showed decreased growth and food consumption when compared to the control and marginally deficient groups. There was a significant difference in XA excretion and plasma PLP and PL levels between all 3 groups with a progressive increase in XA excretion and a progressive decrease in PLP and PL levels from Group to Group 3. Although all groups were found to be in a positive balance for Zn, Cu and Fe, the totally deficient group was in a less positive balance compared to Groups 1 and 2. Furthermore, the percentage excretion of Zn and Cu, when compared to the intake, was greater in this group. This increased excretion, coupled with a decreased food intake, accounted for the lowered Zn and Cu balances in the totally deficient group. Fe excretion did not differ significantly between all 3 groups. The marginally deficient Group 2 showed no significant difference in growth, food consumption, trace element balance and excretion when compared to the control group, indicating the beneficial effects of even subminimal levels of vitamin B-6. This study confirms that the nutritional status of t~ace elements, especially that of Zn and CU, is related to the vitamin B-6 status of the animal.