On the relationship between vitamin A and vitamin E in the rat

Abstract

I . The effect of vitamin E on the metabolism, utilization and storage of vitamin A has been studied in the rat.2. Male weanling rats were given a vitamin A-deficient, vitamin E-deficient diet until growth had ceased for 3 days, and each rat was then given 50 i.u. vitamin A palmitate. The rats were divided into four groups and given the diet with the addition of 10 % methyl oleate or 10 yo cod-liver oil methyl esters, or either of these diets supplemented with IOO ppm D-Utocopheryl acetate. There was no increase in maximum weight-gain response in the two groups given vitamin E. There was a significantly lower weight-gain response in the groups given cod-liver oil methyl esters. This effect was not influenced by the presence of vitamin E in the diet.3. Weanling rats of both sexes were made deficient in vitamins A and E and then divided into two groups. One group received, every other day, 1-75 i.u. vitamin A palmitate and 0.6 mg D-a-tocopherol given together; the second group received the two vitamins, in the same amounts, on alternate days. After zS days there was no difference in the growth of the two groups of rats, irrespective of sex.4. Vitamin A-depleted, vitamin E-deficient rats were given 17.5 I ,ug [14C-carbinol]retiny1 acetate and then a vitamin A-deficient, vitamin E-deficient diet or that diet supplemented with IOO ppm D-a-tocopheryl acetate. After 6 days, the total remaining ['*C]retinol and its lipidsoluble metabolites were measured in the carcasses of the rats. Vitamin E administration did not affect the metabolism of the vitamin A dose or its effect on growth.5. Vitamin E-deficient rats were givenvitaminA until their liver reserves exceeded 30000 i.u. and were then divided into two groups. One group received a diet deficient in vitamins A and E and the other received, in addition to this diet, a weekly oral supplement of I mg D-cc-tocopheryl acetate. The vitamin E supplement significantly decreased the rate of vitamin A depletion from the liver during the next 6 weeks. This effect, which was not found to occur when the initial liver reserves were only 3000 i.u., suggests a role for vitamin E in connexion with the capacity of the liver to bind vitamin A. 6. The relationship between vitamin A and vitamin E in vivo cannot, in the light of these results, be regarded as that between an antioxidant and a peroxidizable substrate.

Vitamin A absorption and metabolism in the chick: response to high dietary intake and to tocopherol

“…It is probable that more samples are required, especially close to the injection time, to describe fully a kinetic model in the chick. Addition of both vitamin A and tocopherol to the diet increased hepatic vitamin A levels as has been previously reported (Cawthorne et al 1968;Sondergaard, 1972;Jenkins & Mitchell, 1975). No differences in absorption between A-and A + E-fed chicks were noted, whereas plasma transport and clearance of vitamin A was enhanced in A + E-treated chicks.…”

“…Addition of tocopherol to high-vitamin-A diets has been reported to alleviate the hypervitaminosis A syndrome (Cawthorne et al 1968;Jenkins & Mitchell, 1975;Sondergaard, 1972) and also enhances the enterohepatic tocopheryl glucuronide secretion (Sklan & Donoghue, 1982).…”

An Apparent Rachitogenic Effect of Excessive Vitamin E Intakes in the Chick

“…However, the addition of excess vitamin E (diets 2 and 4) resulted in a significant increase in plasma vitamin A levels. Excess dietary vitamin E has previously been shown to increase plasma and liver levels of vitamin A (Jenkins and Mitchell, 1975;and Cawthorne et al, 1968). The increased plasma vitamin E observed in chicks consuming the high vitamin E diets would be expected and has been reported by others in both rats (Martin and Hurley, 1977) and chicks (Pudelkiewicz et al, 1960).…”

Inter-relationship between serum retinol and alpha-tocopherol levels in Dhaka University students

“…On the other hand, sex differences in serum levels of vitamin E were found to be insignificant (Leitner el al., 1960;Desai and Lee, 1974;Chen et al, 1977). promotes the absorption, storage and utilisation of vitamin A (Moore, 1940;Cawthorne et al, 1968). Serum vitamin E levels were found to increase gradually with age (Leitner er al., 1960;Desai and Lee, 1974;Chen et al, 1977).…”