The Effect of Mixed Tocopherols on the Utilization of Vitamin A in the Rat

Lemley, Janet M.; Brown, Roy C.; Bird, O. D.; Emmett, A. D.

doi:10.1093/jn/34.2.205

Cited by 30 publications

(7 citation statements)

References 11 publications

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“…of vitamin A per day were given to weanling rats receiving a diet deficient in vitamins A and E, 0.3 mg of a tocopherol concentrate per day stimulated growth. I n contrast to Hickman et al (1944b), however, Lemley et al (1947) found that the synergistic action was maintained when the two vitamins were given on alternate days, and they concluded that there was a sparing effect of vitamin E on vitamin A in the tissues of the animal. Lemley et al (1947) studied also the effect of vitamin E on the storage of vitamin A in liver, after giving the two vitamins simultaneously.…”

Section: Discussionmentioning

confidence: 76%

“…I n contrast to Hickman et al (1944b), however, Lemley et al (1947) found that the synergistic action was maintained when the two vitamins were given on alternate days, and they concluded that there was a sparing effect of vitamin E on vitamin A in the tissues of the animal. Lemley et al (1947) studied also the effect of vitamin E on the storage of vitamin A in liver, after giving the two vitamins simultaneously. They found no effect over a period of 3 days, irrespective of the level of vitamin A given (63-4000 i.u./day).…”

Section: Discussionmentioning

confidence: 76%

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Vitamin E and stress

et al. 1967

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Vitamin E and stress 845 7. ' The interrelationships between polyunsaturated fatty acid stress, vitamin A and vitamin E in the rat and the chick BY J. GREEN I . The nature of the relationship between vitamins A and E has been studied in the rat and the chick. 2.Stress induced by diets rich in polyunsaturated fatty acids (PUFA) was found to have no effect on the liver vitamin A reserves of vitamin E-deficient rats given dietary vitamin A or repeated small oral doses of vitamin A.3. Dietary PUFA did not affect the liver vitamin A reserves of young rats given necrogenic diets deficient in vitamin E and selenium, nor were these reserves affected by the onset of liver necrosis or its prevention by Se. 4.The effect of dietary PUFA on the rate of depletion of liver vitamin A reserves in weanling rats or rats depleted initially of vitamins A and E and then given a single large dose of vitamin Awas studied over periods from 2 to 12+ weeks. In three experiments the dietary PUFA did not significantly accelerate vitamin A depletion. In one experiment the depletion rate was increased, but this was not reversed by dietary vitamin E and thus could not be attributed to an enhancement of peroxidation in vivo but rather to a toxic effect. The effect of vitamin E in these experiments was not consistent but, in general, it slightly decreased the rate of depletion. 6. Large doses of vitamin A (40000 i.u. in total) given to vitamin E-deficient chicks receiving a diet containing I yo linoleic acid (as maize oil esters) did not accelerate the onset of encephalomalacia and therefore failed to exert a pro-oxidative effect on tissue tocopherol.7. The conclusion drawn from these experiments was that any relationship that may exist in vivo between vitamins A and E is not concerned with an effect of vitamin E in preventing oxidation of vitamin A. A critical review of the literature on the nature of the relationship in general supports this view.

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Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 76%

Vitamin E and stress

et al. 1967

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“…assay method are also complicated by their diff erent response to accessory factors in the diet. The importance of adequate tocopherols in the diet has been demonstrated by Hickman (lo), Lemley et al (18) and many others. In the U.S.P.…”

Section: Resultsmentioning

confidence: 88%

A RE‐EVALUATION OF BIOLOGICAL POTENCY OF BETA CAROTENE^a

Barnett¹,

Espoy²

1957

Journal of Food Science

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The International Unit of vitamin A activity was defined in 1934 as the biological response given by 0.6 pg. of pure beta carotene. Subsequently, the United States Pharmacopoeia prepared and distributed several standards consisting of cod liver oil preparations to which were assigned certain biological potencies. These preparations, however, did not prove to be suitable and their biological potency in terms of beta carotene was apparently greatly over-rated. With the isolation and availability of pure vitamin A esters, a new standard was adopted by the United States Pharmacopoeia consisting of a solution of vitamin A acetate in cottonseed oil. On the basis of the vitamin A content of this preparation, 0.3 pg. gives one unit of vitamin A activity. This new unit of vitamin A was presumed to be identical to the old unit based on 0.6 pg. of carotene. If such were the case, it would appear that the organism is able to recover only one molecule of vitamin A from one molecule of carotene.During the past few years, several publications have appeared (2, 3, 17, 20) indicating that under the proper conditions, all-trans beta carotene gives a biological response approaching that given by an equal weight of vitamin A. This agreed with the fact that biological assays on our commercial carotene products derived from carrots were higher than could be explained on the basis of their carotene content.At the present time, most of the carotene being manufactured is used in margarine where its biological activity is included as a part of the vitamin A potency. Inasmuch as the U.S.P. biological assay is the only officially accepted method for the determination of the vitamin A activity of margarine, it is obviously of great importance to know the biological activity of carotene in terms of this assay method. EXPERIMENTALWith but one exception, all of the assays reported here were on crystalline carotene products derived from carrots. Many of the samples were commercial materials which cdntained some alpha carotene along with the beta carotene.The relative amounts of the two carotenes were determined by chromatographic separation on columns of magnesium oxide (Westvaco No. 2642) : Hi-Flo Super Cel or of calcium hydroxide followed by spectrophotometric assays. The concentration of beta carotene was calculated by measurement of the absorbance a t 450 mp in hexane solution and use of an extinction coefficient (EiTJ of 2520. Alpha carotene was measured a t 446 mp using an extinction coefficient of 2720. I n addition, the absorbance ratio

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“…The initial experiments in these studies were designed to determine the influence that vitamin E supplementation would have on the vitamin A nutrition of finishing beef cattle. Moore (1940), Davies and Moore (1941), Hickman et al, (1942), Lemley et al (1947), Koehn (1948), Burns et al (1951 and many others have shown that critical levels of vitamin E supplementation improved the vitamin A nutrition of rats. Experiments 686, 704, 100 and 723 in these studies failed to show that the responses observed following vitamin E supplementation in finishing beef cattle were the result of improved vitamin A nutrition.…”

Section: Discussionmentioning

confidence: 98%

“…The administration of tocopherol without carotene failed to maintain growth. Lemley ^ al. (1947) fed vitamin A and E deficient diets to rats already deficient in both vitamins and showed that small additions of 0.025 mg. mixed tocopherols daily to rats supplemented with 2,04 lU vita min A daily as cod liver oil increased weight gains 13 gm.…”

Section: Bacharach (1940) Reported On a Series Of Experiments In Whicmentioning

confidence: 99%

Vitamin A and E interrelations in high-concentrate finishing rations for beef cattle

Kohlmeier

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The Effect of Mixed Tocopherols on the Utilization of Vitamin A in the Rat

Cited by 30 publications

References 11 publications

Vitamin E and stress

Vitamin E and stress

A RE‐EVALUATION OF BIOLOGICAL POTENCY OF BETA CAROTENE^a

Vitamin A and E interrelations in high-concentrate finishing rations for beef cattle

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The Effect of Mixed Tocopherols on the Utilization of Vitamin A in the Rat

Cited by 30 publications

References 11 publications

Vitamin E and stress

Vitamin E and stress

A RE‐EVALUATION OF BIOLOGICAL POTENCY OF BETA CAROTENEa

Vitamin A and E interrelations in high-concentrate finishing rations for beef cattle

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A RE‐EVALUATION OF BIOLOGICAL POTENCY OF BETA CAROTENE^a