The Interrelationship of Tocopherols and Sulfur Metabolism

The metabolic effects of the tocopherols and or sulfur have been inadvertently linked through research findings. Although not initially postulated, a relationship between vitamin B and sulfur has turned up in such phenomena as prevention of dietary hepatic necrosis, muscular dystrophy, erythrocyte hemolysis; and structural alteration of mucopolysaccharides, proteins, and lipoproteins. The relationship between vitamin E and sulfur remains ill-defined at present; the available information has been obtained as a by-product of research efforts oriented toward other goals. However, an increasing body of evidence indicates that significant behavioral interactions may occur. The present investigation was designed to evaluate possible interrelationships between tocopherol and sulfur metabolism by observing S³⁵O₄-- incorporation into erythrocyte stroma, erythrocyte hemolysis, and circulating sulfhydryl levels of the blood in animals receiving diets varied in amounts and kinds of sulfur and with and without sufficient vitamin E.

Four groups of diets were used; three of these contained essentially the same level of sulfur, calculated as sulfate, but the ratio of inorganic to organic sulfur was varied. The fourth diet contained virtually no inorganic sulfate and was low in organic sulfate. Each diet was tested both vitamin E sufficient and deficient. These diets were fed to eight matched groups of five rats each for a total of 65 days. Blood analyses were made throughout the experiment period for per cent hemolysis and circulating sulfhydryl. At the end of the investigation, the animals were injected with Na₂S³⁵O₄, fasted twenty-four hours, and terminated by withdrawing the blood by cardiac puncture. The erythrocyte stroma was collected and its incorporation of radioactive sulfur determined.

No statistically significant differences were observed with respect to dialuric acid hemolysis between groups. The data on the circulating sulfhydryl and the S³⁵ incorporation into erythrocytes were complementary. Animals receiving no vitamin E and only methionine as the source of sulfur exhibited increased sulfhydryl values and decreased erythrocyte incorporation of S³⁵ at highly significant levels. The converse was true for those animals receiving both methionine and vitamin E. Animals receiving no methionine, but extremely high levels of inorganic sulfate also exhibited a significantly increased erythrocyte incorporation of S³⁵. The sulfhydryl levels of this latter group of animals were observed to be higher than that of any other dietary group. The data obtained from this investigation suggest that adequate vitamin E plays a part in accelerating the conversion of cysteine to sulfate in the rat.