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DRI DIETARY REFERENCE INTAKES FOR Vitamin C, Vitamin E, Selenium, and Carotenoids
(48.7 µmol)/day of α-tocopherol when these diets were analyzed chemically. These two studies indicate that vitamin E intakes from the CSFII and NHANES III surveys are probably underestimated even with the adjustment factor (0.8) and suggest that mean intakes of apparently healthy adults in the United States and Canada are likely to be above the RDA of 15 mg (34.9 µmol)/day of α-tocopherol.
Most dietary vitamin E is present in fats and its oils (Sheppard et al., 1993); therefore, changes in dietary habits to decrease fat intake may have deleterious effects on vitamin E intake (Adam et al., 1995; Bae et al., 1993; Retzlaff et al., 1991; Sarkkinen et al., 1993; Velthuiste Wierik et al., 1996). Patients with coronary artery disease, who did not take vitamin supplements, had average dietary vitamin E intakes of 5.8 mg (13.4 µmol)/day of α-tocopherol equivalents (adjusted to 4.6 mg [10.8 µmol]/day of α-tocopherol) in a 25 percent fat diet containing 2,058 kcal (Mandel et al., 1997). This example demonstrates that low-fat diets can substantially decrease vitamin E intakes if food choices are not carefully made to enhance α-tocopherol intakes.
Dietary Vitamin E Sources
Murphy et al. (1990) evaluated vitamin E intakes from NHANES II. Fats and oils used as spreads, etc. contributed 20.2 percent of the total vitamin E; vegetables, 15.1 percent; meat, poultry, and fish, 12.6 percent; desserts, 9.9 percent; breakfast cereals, 9.3 percent; fruit, 5.3 percent; bread and grain products, 5.3 percent; dairy products, 4.5 percent; mixed main dishes, 4.0 percent; nuts and seeds, 3.8 percent; eggs, 3.2 percent; salty snacks, 3 percent; legumes, 2.1 percent; and soups, sauces, and gravies, 1.7 percent.
As indicated previously, estimation of dietary vitamin E intake is difficult because the source of oil is often not known with certainty. Lehmann et al. (1986) analyzed the foods used in a human diet study for vitamin E content. Each menu was designed to contain 2,400 kcal with 35 percent fat calories and included either 10 or 30 g/day of linoleic acid and 500 mg/day of cholesterol; the high linoleic acid diet contained 10 g of safflower oil. As shown in Figure 6-9, substituting various oils for the 10 g of safflower oil resulted in vitamin E intakes that varied from 6.9 to 13.8 mg (16 to 32 µ mol)/day of α-TE depending on the source of the vegetable oil (vitamin E contents were estimated from Lehmann et al., 1986, and Dial and Eitenmiller, 1995).