| Abstrakt: |
β-Carotene and excess vitamin A have been shown to reduce plasma α-tocopherol when fed to young rats. The present study assessed the effects of β-carotene, excess vitamin A and canthaxanthin (4,4′-diketo-β-carotene) on carotenoid, α-tocopherol and iron status in adult retired breeder rats. Male 8- to 10-mo-old rats (10/group) were fed varying levels of vitamin A as retinyl palmitate, β-carotene and canthaxanthin ad libitum for 8 wk. The AIN-76A diet was modified to contain 16% (wt/wt) fat and 50% carbohydrate (control) plus β-carotene or canthaxanthin at 0, 0.048 (BC1 or CX1) and 0.2% (BC2 or CX2) of the diet. These compounds were fed with and without excess retinyl palmitate (RP, 220 mg/kg). Higher relative liver weights were observed in CX- and RP-fed groups. Plasma retinyl esters were detected in all RP-fed groups. Plasma retinyl palmitate was 1.6- and 1.5-fold higher in RP-BC and RP-CX groups, respectively, than in the RP groups. Plasma and liver β-carotene and canthaxanthin were 11–54% and 26–74% lower, respectively, with excess retinyl palmitate feeding. Feeding canthaxanthin and retinyl palmitate, but not β-carotene, resulted in lower levels of plasma α-tocopherol. Liver non-heme iron levels were also lower in CX-fed rats irrespective of retinyl palmitate feeding. These results extend to adult rats previous findings that excess retinyl palmitate alters vitamin E and carotenoid status prior to the manifestation of clinical signs of hypervitaminosis A. Additionally, canthaxanthin feeding lowers α-tocopherol and iron status in adult rats. |
