The effect of pyridoxine on the number of lymphocytes in the blood of rats fed caramel colour (III).

The effect of vitamin E, folic acid, pyridoxine (vitamin B6) and choline on the reduction in circulating lymphocytes in the blood of rats fed Caramel Colour (III) also known as ammonia caramel colour (beer type; AC) has been examined. It was found that the reduction in the number of circulating lymphocytes in rats fed AC could be prevented by the addition of pyridoxine to the diet. The activity of AC in reducing the number of circulating lymphocytes also closely resembled that of the pyridoxine antagonist 4'-deoxypyridoxine. After the isolation and identification of 2-acetyl-4(5)-tetrahydroxybutylimidazole (THI), comparative studies indicated that THI was the component of AC responsible for reducing the number of circulating lymphocytes. Although the effect of AC was reduced or prevented by increasing dietary pyridoxine, the lymphocyte reduction associated with the administration of THI was not materially affected by the dietary level of pyridoxine.