Hypervitaminosis is a condition of abnormally high storage levels of vitamins, which can lead to various symptoms—whether physiological, such as pain, nausea, and tachycardia, or psychological, such as confusion, hyperactivity, and irritability—and even to toxicity. Specific medical names of the different conditions are derived from the given vitamin involved: an excess of vitamin A, for example, is called hypervitaminosis A. Hypervitaminoses are primarily caused by fat-soluble vitamins (especially 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. Toxicities of fat-soluble vitamins can also be caused by a large intake of highly fortified foods, but natural foods in modest levels seldom deliver extreme or dangerous levels of these vitamins.

  • Frequent urination 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 D
  • Vitamin B<sub>3</sub> § Toxicity
  • Megavitamin-B<sub>6</sub> syndrome
  • Vitamin E toxicity

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

See also

  • Avitaminosis
  • Megavitamin therapy
  • Vitamin C megadosage

References

  • Dietary reference intakes, official website.