Effect of Dietary Linoleic Acid on Vitamin E Requirement and Fatty Acid Composition of Erythrocyte Lipids in Rats

Abstract

In order to investigate the effect of an increasing linoleic acid content of the diet on vitamin E requirement, young male rats were divided into 4 groups receiving respectively 0.27, 0.98, 3.57 and 12.98% linoleic acid (from mixtures of coconut oil and tocopherol-free safflower oil) in their diets. Each group was subdivided into 6 groups, receiving increasing amounts of D-α-tocopheryl acetate (2.5–23.5 mg) in their food. Spontaneous haemolysis in vitro was used as a criterion for vitamin E requirement. The amount of D-α-tocopheryl acetate needed to prevent haemolysis was 13 mg/kg food for the lowest three doses linoleic acid, the highest dose required 18 mg/kg food. The fatty acid composition of erythrocyte lipids was not influenced by the vitamin E content and only moderately by the linoleic acid content of the diet: a higher level of dietary linoleic acid caused an increase in linoleic acid content of erythrocyte lipids, which was mainly compensated by a decrease in oleic acid content. The group with the lowest dose of vitamin E and the highest dose of linoleic acid showed a significant increase in non-electrolyte (= thiourea) haemolysis time.

Effect of Dietary Linoleic Acid and Selenium on the Requirement of Vitamin E in Ducklings

“…With respect to the small effect of linoleic acid intake on vitamin E re quirement, the results of this experiment on ducklings are in agreement with previous results on rats [1,2]. Sg n d e r g a a r d and D am [41] found no effect of the level of dietary linoleic acid (up to 10 cal% of the diet) on the amount of vitamin E, required for protection against encephalomalacia in chickens.…”

“…The in vitro haemolysis test may be con-sidercd as a typical example of vitamin E acting as an antioxidant, the degree of haemolysis and, therefore, the vitamin E requirement being dependent upon the sensitivity of the erythrocyte membrane lipids to peroxidation [40], If, however, care is taken that the diets contain sufficient EFA. a wide variation in dietary linoleic acid contents is possible, without causing any appreciable effect on the percentage of arachidonic acid in the erythrocyte fatty acids [2], which is equally true of the linoleic acid intake on vitamin E requirement in the haemolysis test, except for very high doses of vitamin E [2].…”

“…They con cluded that polyunsaturated vegetable oils, such as cottonseed oil and maize oil contain sufficient amounts of vitamin E for growth, reproduction, lacta tion and normal lipid metabolism. Table IV details different oils with respect to their vitamin E status and linoleic acid contents, taking into account that an increase in vitamin E requirement is to be expected if an oil contains more than 20% linoleic acid [2].…”

“…High linoleic acid intake is known to induce an increased requirement for vitamin E, as demonstrated by an in vitro haemolysis test [1,2]. Although a distinct relation has been found between the percentages of in vitro spon taneous haemolysis and degree of myopathy in rats [3], there is no proof that under conditions of a high linoleic acid intake, in vitro haemolysis, necessarily gives a valid estimation of vitamin E requirement in tissues other than blood.…”

The Influence of Vitamin E Deficiency and Combined Deficiency in Vitamin E and Polyunsaturated Fatty Acids on the Biosynthesis and Degradation of Rat Central Nervous System Myelin

“…Thus, opposite to the findings in chicks (35), the vitamin E deficiency did not give rise to CNS symptoms in the rat. The term 'deficient' is justified by comparison to the work of Jager (18) and Jager and Houtsmuller (21), as the present diet contained less than 1 mg of vitamin E per kilogram and Jager showed that 5 mg/kg diet was low enough to induce an 80% in vitro haemolysis. Furthermore, the present finding of lowered gain in weight as a result of deficiency in vitamin E would, according to Jager (19), only occur when the dietary content of vitamin E is lower than 1.5 mg/kg food.…”