Fat soluble vitamins
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A fat-soluble vitamin is a vitamin that can dissolve in dietary fats. They are stored in body fat.
[edit] List of fat soluble vitamins
- Vitamin A: The tolerable upper intake level for adults is 3,000 mcg RAE.
- Vitamin D: The tolerable upper intake level is set at 50 mcg for people 1 year of age and older.
- Vitamin E: The tolerable upper intake levels for vitamin E varies. Large doses of vitamin E pose a hazard to people who take blood-thinning medications.
- Vitamin K: The tolerable upper intake level has not been established for vitamin K, excessive amounts can cause the breakdown of red blood cells and liver damage. Large doses are not advised.[1]
The fat soluble vitamins are absorbed from the terminal ileum, and so pathology at this location can lead to their deficiency (e.g. ileal resection, Crohn's disease). They can also become deficient in poor diets, malabsorption (e.g. cystic fibrosis) and obstructive jaundice (bile is required in the duodenum/ileum to facilitate fat absorption).
Fat soluble vitamins are mostly found in fatty foods and fish-liver oils and are particularly rich in vitamins A and D. A certain amount of fat is needed in the diet to help the body absorb these vitamins. Vitamins A and D are also found in human liver and if the diet contains more vitamin A or D than is immediately required the surplus is stored in the liver. Enough of these vitamins is stored in the liver of a well-nourished person to satisfy the body's needs for several months if they are absent from the diet. If the diet contains too much vitamin A or D, however, the surplus will accumulate in the liver and may be harmful. Such excessive intakes are less likely to result from over-eating than through over-enthusiastic use of vitamin pills or dietary supplements.
