Vitamin poisoning

Vitamin poisoning, or hypervitaminosis, refers to a condition of high storage levels of vitamins, which can lead to toxicsymptoms. The medical names of the different conditions are derived from to the vitamin involved: an excess of vitamin A, for example, is called "hypervitaminosis A".

Some of the most common causes of poisoning are vitamins A, B₃and B₆. Conversely, certain vitamins do not produce toxicity in excess levels: vitamin Chas been used in clinical trials in dosages over 100,000 mg? over 1000 times the daily recommended intake? without ill effects.

Excess doses of mineral supplementscan also lead to poisoning. Either or both of hypervitaminosis and mineral supplement poisoning can occur due to excessive intake of multivitaminsupplements.

Hypervitaminosis A

The effects of vitamin A poisoning include:

• birth defects
• liverabnormalities,
• reduced bone mineral densitythat may result in osteoporosis
• hair loss
• excessive skin dryness/peeling

Signs of acute toxicity include nauseaand vomiting, headache, dizziness, blurred vision, and loss of muscularcoordination.

Although hypervitaminosis A can occur when very large amounts of liver are regularly consumed, most cases of vitamin A toxicity result from an excess intake of vitamin A in supplements. Toxic symptoms can also arise after consuming very large amounts of preformed vitamin A over a short period of time.

The Institute of Medicine has established Daily Tolerable Upper Levels (UL) of intake for vitamin A from supplements that apply to healthy populations, in order to help prevent the risk of vitamin A toxicity. These levels for performed vitamin A in micrograms(µg) and International Units(IU) are:

• 0-3 years: 600 µg or 2000 IU
• 4-8 years: 900 µg or 3000 IU
• 9-13 years: 1700 µg or 5665 IU
• 14-18 years: 2800 µg or 9335 IU
• 19+ years: 3000 µg or 10,000 IU

Hypervitaminosis D

In terms of the likelihood of poisoning, Vitamin Dseems to be one of the least poisonous substances known. Overdose occurs at more than 100 times the daily RDA (more or less a bottle of vitamin D tablets per day), for several months. Acute one-time overdose requires over 50mg (ten thousand times the RDA). Foods contain low levels, and have not been known to cause overdose.

Although taking excessive amounts of cod liver oil over months or years could produce an overdose in theory, it is almost always associated with forms of vitamin D that require a doctor's prescription. Overdose has also occurred due to industrial accidents, for example when incorrectly formulated pills were sold.

Symptoms of vitamin D poisoning include:

• Dehydration
• Vomiting
• Decreased appetite (anorexia)
• Irritability
• Constipation
• Fatigue

An excess of vitamin D causes abnormally high blood concentrations of calcium which can eventually cause severe damage to the bones, soft tissues, and kidneys. It can also damage the kidney and produce kidney stones.

Note: Hypervitaminosis D symptoms appear several months after excessive doses of vitamin D are administered, by which time the condition is usually very serious.

See also

• Avitaminosis

External links

• Facts about Vitamin A and Carotenoids, from the National Institutes of Health's Office of Dietary Supplements.
• Hypervitaminosis D Medical Information

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Vitamin+poisoning Wikipedia article Vitamin poisoning.