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Hypervitaminosis refers to a condition of abnormally high storage levels of vitamins, which can lead to toxic symptoms. The medical names of the different conditions are derived from the vitamin involved: an excess of vitamin A, for example, is called hypervitaminosis A. Hypervitaminosis primarily affects the Fat Soluble Vitamins, as these are stored by the body for longer timeframes than the Water Soluble Vitamins. However, avoiding true excesses of both classes of vitamins can make the condition hard to get. Generally, toxic levels of vitamins stem from high supplement intake and not from dietary sources. Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but foods rarely deliver dangerous levels of fat-soluble vitamins.〔 The Dietary Reference Intake recommendations from the United States Department of Agriculture define a "tolerable upper intake level" for most vitamins. High dosage vitamin A; high dosage, slow release vitamin B3; and very high dosage vitamin B6 alone (i.e. without vitamin B complex) are sometimes associated with vitamin side effects that usually rapidly cease with supplement reduction or cessation. ==Fat soluble== With few exceptions, like some vitamins from B complex, hypervitaminosis usually occurs more with fat-soluble vitamins (D, E, K and A or 'DEKA'), which are stored in the liver and fatty tissues of the body. These vitamins build up and remain for a longer time in the body than water-soluble vitamins. Conditions include: * Hypervitaminosis A * Hypervitaminosis D * Hypervitaminosis E * Hypervitaminosis K, unique as the true upper limit is less clear as is its bioavailability. According to Williams' Essentials of Diet and Nutrition Therapy (Mosby, 10th Edition) It is difficult to set a DRI for vitamin K because part of the requirement can be met by intestinal bacterial synthesis. * Reliable information is lacking as to the vitamin K content of many foods or its bioavailability. With this in mind the Expert Committee established an AI rather than an RDA. * This RDA (AI for men age 19 and older is 120 µg/day, AI for women is 90 µg/day) is adequate to preserve blood clotting, but the correct intake needed for optimum bone health is unknown. Toxicity has not been reported. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hypervitaminosis」の詳細全文を読む スポンサード リンク
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