Toxicity Of Fat Soluble Vitamins

Your body can store excess amounts of the fat-soluble vitamins A, D, E and K for use when your dietary intake is inadequate. This property helps to ensure that you do not fall short of your fat-soluble vitamin needs so your body can carry out important functions. Unfortunately, the ability to store excess amounts of vitamins can also lead to vitamin toxicity, which is characterized by adverse health effects caused by too much of a vitamin.

Vitamin A

Vitamin A is available in two major forms: preformed vitamin A and provitamin A carotenoids. Overconsumption of preformed vitamin A, which usually occurs as a result of excess supplementation, can cause side effects, such as nausea, vomiting, headache, dizziness and blurred vision. Prolonged overconsumption can lead to a potentially dangerous condition called hypervitaminosis A, which is characterized by accumulation of vitamin A in the liver. Over time, hypervitaminosis A can lead to extensive scarring of the liver and loss of function. The Food and Nutrition Board set the upper limit for preformed vitamin A at 3,000 mg per day.

Overconsumption of provitamin A carotenoids can lead to a condition called carotenodermia. This condition is characterized by an orange tint to the skin, especially on the palms of the hands and soles of the feet. Carotenodermia is not dangerous and can usually be reversed by reducing your intake of foods that are rich in provitamin A carotenoids.

Vitamin D

Consuming too much vitamin D, either through foods or supplements, can cause negative gastrointestinal effects, such as nausea, vomiting, constipation and loss of appetite. Chronic overconsumption can lead to a toxic condition called hypervitaminosis D, which leads to overabsorption of calcium in the intestines and calcium loss from the bones. These two conditions can lead to dangerously high levels of calcium in the blood, a condition called hypercalcemia. The upper limit for vitamin D is 2,000 IU per day.

Vitamin E

There is no risk of consuming excess amounts of vitamin E from foods, but excess supplementation or overconsumption of fortified foods can lead to toxicity. Vitamin E acts as an anticoagulant, so excess amounts in the body can lead to hemorrhaging. The upper limit for vitamin E, which applies to supplements and fortified foods, is set at 1,000 mg per day.

Vitamin K

Currently, no evidence shows that excessive intake of vitamin K, either through food or supplementation, causes adverse health effects. Because of this, the Food and Nutrition Board has not established an upper tolerable intake level for the vitamin.