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|Classification and external resources|
Hypervitaminosis is a condition of abnormally high storage levels of vitamins, which can lead to toxic symptoms. Specific medical names of the different conditions are derived from the vitamin involved: an excess of vitamin A, for example, is called hypervitaminosis A. Hypervitaminoses are primarily caused by fat-soluble vitamins (D and A), as these are stored by the body for longer period than the water-soluble vitamins.
Generally, toxic levels of vitamins stem from high supplement intake and not from natural food. Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural food 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.
With few exceptions, like some vitamins from B-complex, hypervitaminosis usually occurs more with fat-soluble vitamins (A, D, E and K), 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 K, unique as the true upper limit is less clear as is its bioavailability. Toxicity has not been reported.
- High-dosage, slow-release vitamin B3; Niacin; and very high-dosage vitamin B6 alone (i.e. without vitamin B complex) hypervitaminoses are sometimes associated with side effects that usually rapidly cease with supplement reduction or cessation.
In the United States, overdose exposure to all formulations of "vitamins" (which includes multi-vitamin/mineral products) was reported by 62,562 individuals in 2004 with nearly 80% of these exposures in children under the age of 6, leading to 53 "major" life-threatening outcomes and 3 deaths (2 from vitamins D and E; 1 from polyvitaminic type formula, with iron and no fluoride). This may be compared to the 19,250 people who died of unintentional poisoning of all kinds in the U.S. in the same year (2004). In 2010, 71,000 exposures to various vitamins and multivitamin-mineral formulations were reported to poison control centers, which resulted in 15 major reactions but no deaths.
- "Office of Dietary Supplements - Vitamin A". ods.od.nih.gov. Retrieved 2016-02-03.
- Sizer, Frances Sienkiewicz; Ellie Whitney (2008). Nutrition: Concepts and Controversies (11 ed.). United States of America: Thomson Wadsworth. pp. 221, 235. ISBN 0-495-39065-8.
- Toxic Exposure Surveillance System (2004). "Annual Report" (PDF). American Association of Poison Control Centers. Archived from the original (pdf) on 2011-01-05.
- "National Center for Health Statistics".
- Bronstein, A. C.; Spyker, D. A.; Cantilena, L. R.; Green, J. L.; Rumack, B. H.; Dart, R. C. (2011). "2010 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 28th Annual Report". Clinical Toxicology. 49 (10): 910–941. doi:10.3109/15563650.2011.635149. PMID 22165864.
- Dietary reference intakes, official website.