Hypervitaminosis is a condition of abnormally high storage levels of

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

s, which can lead to various symptoms as over excitement, irritability, or even

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...

. Specific medical names of the different conditions are derived from the given vitamin involved: an excess of

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably ...

, for example, is called

hypervitaminosis A Hypervitaminosis A refers to the toxic effects of ingesting too much preformed vitamin A (retinyl esters, retinol, and retinal). Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hypervi ...

. Hypervitaminoses are primarily caused by fat-soluble vitamins ( D and A), as these are stored by the body for longer than the water-soluble vitamins. Generally, toxic levels of vitamins stem from high supplement intake and not always from natural sources but rather the mix of natural, derived vitamins and enhancers (vitamin boosters). Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural food in modest levels rarely deliver extreme or dangerous levels of fat-soluble vitamins. The

Dietary Reference Intake The Dietary Reference Intake (DRI) is a system of nutrition recommendations from the National Academy of Medicine (NAM) of the National Academies (United States). It was introduced in 1997 in order to broaden the existing guidelines known as Re ...

recommendations from the

United States Department of Agriculture The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of comme ...

define a "tolerable upper intake level" for most vitamins. For those who are entirely healthy and do not experience long periods of avitaminosis, vitamin overdose can be avoided by not taking more than the normal or recommended amount of multi-vitamin supplement shown on the bottle and not ingesting multiple vitamin-containing supplements concurrently.

Signs and symptoms

A few described symptoms: * Frequent urination and/or cloudy urine * Increased urine amount * Eye irritation and/or increased sensitivity to light * Irregular and/or rapid heartbeat * Bone and joint pain (associated with avitaminosis) * Muscle pain * Confusion and mood changes ( e.g. irritability, inability to focus) * Convulsions * Fatigue * Headache * Flushing of skin (associated with niacin (vitamin B3) overdose) * Skin disturbances (e.g. dryness, itching, cracking of skin, rashes, increased sensitivity to sun) * Changes of hair texture (e.g. thickening and/or clumping of hair) * Appetite loss * Constipation (associated with iron or calcium overdose) * Nausea and vomiting * Diarrhoea * Moderate weight loss (more commonly seen in long-term overdose cases)

Causes

With few exceptions, like some vitamins from B-complex, hypervitaminosis usually occurs with the fat-soluble vitamins A and D, which are stored, respectively, 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 A refers to the toxic effects of ingesting too much preformed vitamin A (retinyl esters, retinol, and retinal). Symptoms arise as a result of altered bone metabolism and altered metabolism of other fat-soluble vitamins. Hypervi ...

* Hypervitaminosis D * Vitamin B₃ § Toxicity * Megavitamin-B₆ syndrome

Prevention

Prevention in healthy individuals not having any periods of avitaminosis or vitamin (vegetables) lack for 2 years at least is by not taking more than the expected normal or recommended amount of vitamin supplements.

Epidemiology

In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

, 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 a

multivitamin A multivitamin is a preparation intended to serve as a dietary supplement with vitamins, dietary minerals, and other nutritional elements. Such preparations are available in the form of tablets, capsules, pastilles, powders, liquids, or injecta ...

with iron). 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 2016, overdose exposure to all formulations of vitamins and multi-vitamin/mineral formulations was reported by 63,931 individuals to the

American Association of Poison Control Centers The American Association of Poison Control Centers (AAPCC) is a national nonprofit organization founded in 1958 that represents the nation's 55 poison centers. The AAPCC supports poison centers in their public health mission to prevent poisonin ...

with 72% of these exposures in children under the age of five. No deaths were reported.

References

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