No abstract

Plasma, RBC, platelets, and lymphocytes from human subjects on graded intakes of vitamin E were analyzed for tocopherols to determine which humoral compartment most closely followed changes in the dietary intake. Relative merits of the various blood elements to reflect changes in vitamin E intake were calculated by the sensitivity concept of Mandel and Stiehler (ie, rate of change of tocopherol levels with dose divided by the standard deviation). Sensitivities of alpha-tocopherol levels of the various blood components to vitamin E intake decreased in the order platelets greater than RBC greater than plasma lipids greater than plasma greater than lymphocytes. Changes in tocopherol levels in platelets most closely followed changing dietary intakes of vitamin E when compared with data from RBC, lymphocytes, and plasma. Furthermore, for studying the effects of diets on vitamin E status, tocopherol levels of platelets appear to be a better measure than tocopherol levels of either RBC, lymphocytes, or plasma lipids.

177Vitamin E isomers are important antioxidants, but their variation is poorly documented in pseduocereal grains such as amaranths. Using normal-phase, high-performance liquid chromatography with fluorescence detection, seeds of thirteen amaranth (Amaranthus cruentus L., A. hypochondriacus L.) accessions were surveyed for the composition of tocols. The most common tocols found were a-tocopherol (2.97 to 15.65 mg/kg seed) and ~-tocotrienol (5.92 to 11.47 mg/kg seed) and T-tocotrienol (0.95 to 8.69 mg/kg seed), while some A. cruentus accessions contained 5-tocotrienol (0.01 to 0.42 mg/kg seed). This is the first report of tocotrienols in amaranths. Amaranthus cruentus grain-types of Mesoamerican origin had significantly (P _< 0.01) greater levels of four tocols than did A. cruentus African vegetable-types. Unlike many cereal grains, amaranths have significant amounts of both ~-and T-tocotrienols; however, ~-tocopherol was not detected in any of the amaranths. Using multiple linear regressions, a-tocopherel variation of both species and types was consistently explained by variation in tocols other than a-tocopherel. On the whole, fresh amaranth samples of both species tended to have higher levels of tocotrienols than samples stored for two years. Storage effects on amaranth tocol composition are suspected.

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%.

A method is described for the analysis of foods for the forms of vitamin E. Detailed procedures are given for extraction, saponification and partial purification by thin layer chromatography. The individual tocopherols (both tocols and tocotrienols) are identified and estimated as their trimethylsilyl ethers by gas liquid chromatography on SE‐30 or Apiezon L at 235 C. Retention ratios are also given for separations on OV‐17. Response factors relative to didecyl pimelate as an internal standard and overall recoveries were determined for α‐tocopherol, β‐tocopherol, γ‐tocopherol, δ‐tocopherol, β‐tocotrienol and α‐tocotrienol. Sample sizes depended on tocopherol content and were usually chosen to contain 3–50 µg of the individual tocopherols. Data for a number of seeds and oils are given. The greatest variety of forms was found in barley, which contains all the forms listed above, plus γ‐tocotrienol.