Comparative sensitivities of tocopherol levels of platelets, red blood cells and plasma for estimating vitamin E nutritional status in the rat.

The use of tocopherol levels of either platelets or red blood cells was tested as an index of tissue vitamin E status. Male Wistar rats were fed 0, 5, 10, 20, or 50 ppm of vitamin E (d-alpha-tocopheryl acetate) ad libitum for 10 wk. Over the dosage range from 0 to 20 ppm, response in tocopherol content of most tissues including platelets and red blood cells were linear. Over the whole range from 0 to 50 ppm, responses were curvilinear both directly and logarithmically for all tissues. In a comparison of reproducibility of responses of platelets, plasma and red blood cells, the variation of alpha-tocopherol content within groups fed the same diet was consistently lowest for platelets. Sensitivity (linear slope/SD) for reflecting vitamin E intake was higher for platelets than for either red blood cells or plasma. In vitro spontaneous hemolysis of red blood cells was less than 10% with 10 ppm of vitamin E, greater than 85% with 0 ppm, and was variable (2 to 78%) with 5 ppm. Lipid levels in plasma increased significantly as vitamin E was increased from 5 to 50 ppm of the diets. Over this range, levels of cholesterol and phospholipid increased 20% and levels of triglyceride increased almost 200%.