Upper Levels of Intake

Vitamin E seems to have very low toxicity, and habitual intake of supplements of 200 to 600 mg per day (compared with an average dietary intake of 8 to 12 mg) seems to be without untoward effect; there are no consistent reports of adverse effects up to 3,200 mg per day, suggesting that an acceptable daily intake is in the very wide range between 0.15 to 2 mg per kg of body weight; the European Health Food Manufacturers' Association suggests an upper limit of 800 mg per day from supplements (Shrimpton, 1997).

Very high intakes may antagonize vitamin K and hence potentiate anticoagulant therapy. This is probably the result of inhibition of the vitamin K quinone reductase, but a-tocopheryl quinone may compete with vitamin K hydroquinone and hence inhibit carboxylation of glutamate in target proteins (Section 5.3.1).

The U.S./Canadian tolerable upper level is set at 1,000 mg per day, based on reports of prolonged prothrombin time in people receiving anticoagulants and consuming 1,100 to 2,100 mg of vitamin E per day. It is noteworthy that although the report specifically excluded the 2S isomers of synthetic a-tocopherol from calculations of nutritional requirements, this tolerable upper level includes all forms of the vitamin, regardless of their tissue retention and biological activity (Institute of Medicine, 2000).

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