What are the Fat Soluble Vitamins?

Vitamins A, D E and K, Food Sources, Deficiency, Hypervitaminosis

Sep 12, 2009

The fat soluble vitamins are vitamins A, D, E and K. These are stored in the body and do not need to be consumed daily. Deficiency or hypervitaminosis can be serious.

Fat soluble vitamins have a variety of important functions in the body, and if inadequate amounts are obtained from the diet, deficiency symptoms may occur. Conversely, excess supplementation of these vitamins can have toxic effects. Fat soluble vitamins are found in a variety of foods, and obtaining adequate amounts of them can easily be accomplished by eating a varied diet.

Fat Soluble Vitamins

The four fat soluble vitamins are vitamins A, D, E and K, and after being ingested, they are stored by the body in fatty tissues. Fat soluble vitamins must be obtained from plant and animal foods, except for vitamin D, as humans can synthesise this themselves in the presence of sunlight.

Vitamins A, D and K are stored in the liver, while vitamin E is stored in adipose tissue. The body’s storage of fat soluble vitamins means a continuous, daily intake is unnecessary. Fat soluble vitamins accumulate in the body, and excessive vitamin intake, or hypervitaminosis, can be harmful to health.

Sources of Vitamins A and D, Deficiency and Hypervitaminosis

Vitamin A is also known as retinol or carotene. It is found in green, yellow and orange vegetables and fruits, dairy products, fortified margarine, egg yolks, liver, and fish-liver oil. Vitamin A is needed for healthy skin and the maintenance of body tissues, as well as good night vision and strengthened resistance to infections. Vitamin A deficiency can lead to night blindness or even complete blindness. Hypervitaminosis A can cause birth defects, bone swelling, pruritis (intense itching) and weight loss in children, as well as alopecia, brittle bones, diarrhoea, headaches, lethargy and nausea in adults.

Vitamin D is also known as calciferol and cholecalciferol. With regular exposure of skin to sunlight, the body can synthesise sufficient amounts of vitamin D, but it is also found in fish-liver oils (especially cod-liver oil), eggs, dairy products and fortified foods. Vitamin D is important for the absorption of calcium and strong bones. Deficiency symptoms can include rickets and osteomalacia (softening of the bones). Hypervitaminosis D can cause diarrhoea, nausea, weight loss and kidney damage.

Food Sources of Vitamins E and K, Functions and Deficiency Symptoms

Vitamin E is also known as tocopherol. It is an antioxidant, and is found in nuts, seeds, green vegetables, plant oils and margarines. Vitamin E deficiency may lead to anaemia, but the effects of an overdose from vitamin E are not clear.

Vitamin K is also known as phylloquinone. It is found in green vegetables, vegetable oils, meat and cereals, and is also manufactured by intestinal bacteria. Vitamin K is essential for blood clotting and a deficiency could lead to bleeding and haemorrhages. The effects of excessive consumption of vitamin K are unclear.

Fat soluble vitamins can be obtained in sufficient amounts by eating a balanced diet, but vitamin supplements are available in the event of inadequate nutrition. Care must be taken when using supplements, especially with vitamins A and D, as excessive consumption can be damaging to health.

The copyright of the article What are the Fat Soluble Vitamins? in Vitamins & Minerals is owned by Sharon Kirby. Permission to republish What are the Fat Soluble Vitamins? in print or online must be granted by the author in writing.