Fat-soluble vitamins

Fat-soluble vitamins A, D, E, and K absorbed from food in the small intestine with dietary lipids. They tend to be accumulated in the adipose tissue and liver; when vitamins don't come with food, the body will use it from the storage. Small quantities of all fat-soluble vitamins are required and most likely supplements of vitamins aren't needed. Generally, vitamins A, D, E, and K might be associated with a risk of toxicity when consumed in excess.

Vitamin A (Retinol)

There are two forms of vitamin A: preformed vitamin A (retinol and retinyl ester) and provitamin A - carotenoids (beta-carotene, alpha-carotene, and beta-cryptoxanthin). Preformed vitamin A comes from animal products and carotenoids found in plants. In the body, both forms of vitamin A must be metabolized intracellularly to the active forms of vitamin A (retinal and retinoic acid). Most individuals receive a sufficient amount of vitamin A from a well-balanced diet. High doses vitamin A may be toxic and harmful.

  • Helps in cell regeneration
  • Is vital for vision
  • Works as an antioxidant
  • Plays a role in the formation and maintenance of the structure and function of bones, teeth, and skin
  • Boosts the immune system
  • Plays a role in reproduction, growth and wound healing.

Sources: fish oil, eggs, liver, milk, cream, cheese, margarine, greens, green and yellow fruits and vegetables. Abundantly present in carrots, squash, mango, and other yellow vegetables and fruits.

Vitamin E (Tocopherol)

  • Works as an antioxidant
  • Supports erythrocytes productions
  • Helps the body to use vitamin K
  • Protects against cell membranes damage
  • Has a positive effect on the sex glands, nervous and muscle tissue.

Sources: fish oil, greens, wheat germ, sunflower oil, unrefined vegetable oils, avocados, margarine, nuts, and seeds.

Vitamin K (Phylloquinone)

  • Plays a major role in blood clotting;
  • Plays an important role in bone health.

Sources: liver, greens, cabbage, cauliflower. Most RDA is met by synthesis by intestinal bacteria.

Vitamin D (cholecalciferol)

  • Promotes calcium and phosphorus exchange
  • Builds and maintains healthy bones
  • Boosts the immune system
  • Helps prevent osteomalacia and osteoporosis
  • Aids blood sugar regulation
  • Play role in cancer prevention.

Sources

  • Exposure to UV light is the most effective way to obtain vitamin D.
  • Cold waters fish, cod liver oil, fish caviar, eggs yolk, fortified milk, white mushrooms, and some cheese.

Certain diseases often diagnosed as vitamin A deficiencies, which can cause night blindness, dry skin and hair, dry conjunctiva and cloudy cornea, weak bladder sphincter, pancreatic cancer, cervical erosion, anemia, insomnia, respiratory, and digestive infections.

On the other hand, an excess of vitamin A is also a dangerous condition and may cause nausea and vomiting, anorexia, headache, pain, and fragility of the bones, an enlarged liver and spleen, and birth defects. An overdose of B6, C, D and E vitamins could be a reason for toxic side effects. One day multivitamin supply should contain less 2 times the daily value.

Some people take excessive amounts of vitamins – doses 10 to 1,000 times the RDA, believing they can improve the health conditions or athletic performance. This is not the case. Since vitamins are not burned as fuel and small amounts are needed for metabolic reactions, there is no evidence that megadoses of vitamins supplements are able to improve health and athletic performance except when used to correct a dietary deficiency or some health conditions. Due to water-soluble vitamins are quickly excreted by the kidney, and fat-soluble accumulate in adipose tissue and liver, an excess of fat-soluble vitamins can be especially dangerous.

Recommended Dietary Allowances

Recommended Dietary Allowances (RDA) are the recommended quantities of vitamins for healthy persons. RDAs may vary depending on a person's age, sex, and physical condition. Most vitamins must be obtained from a well-balanced diet.

Fat-soluble RDA (mg)
Vitamin A (Retinol) 1
Vitamin E (Tocopherol) 10
Vitamin K (Phylloquinone) 0.08
Vitamin D3 (Cholecalciferol) 0.01
Highlights

  Vitamins A, D, E, and K do not lost during cooking

Small amounts of all fat-soluble vitamins are required to maintain good health. 

  Megadoses of fat-soluble vitamins are accumulated in the liver and fat tussies and can cause toxicity

  The body can use vitamins A, D, E, and K that stored in the liver or fat.