Vitamins are classified as either fat soluble or water-soluble. This difference between the two groups is very important as it determines how each vitamin acts within the body. The fat-soluble vitamins are soluble in lipids (fats). These vitamins are usually absorbed in fat globules (called chylomicrons) that travel through the lymphatic system of the small intestines and into the general blood circulation within the body.
Stored by the body for future use
The body does not need these vitamins every day, as unlike water-soluble vitamins that need regular replacement in the body, fat-soluble vitamins are stored by the body for future use. They are stored mainly in the liver and fatty tissues. While it serves us well be able to build up a store of these vitamins so that they are there when we need them, if we consume more than we need it leads to toxicity.
The body can be deficient in the fat-soluble vitamins if fat intake is too low or if fat absorption is compromised, for example, by certain drugs that interfere with the absorption of fat from the intestine or by certain diseases such as cystic fibrosis in which there is a deficiency of enzymes from the pancreas which similarly interferes with the absorption of fat from the intestine.
Fat-soluble vitamins are found mainly in fatty foods such as animal fats, including butter and lard, vegetable oils, dairy foods, liver and oily fish. You might also be interested to know that, unlike water-soluble vitamins, fat-soluble vitamins are not destroyed by the cooking process.
Essential to be consumed with food
The best way to take any kind of fat-soluble supplement is with food - your body will not be able to dissolve or absorb the vitamin otherwise. A glass of low-fat milk, for example would provide a sufficient amount of fat to help your body absorb the vitamin.
Fat-soluble vitamins are:
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
Is also known as Retinol and has several important functions including strengthening immunity against infections, helping vision in dim light, and is involved in keeping skin and the linings of some parts of the body, such as the nose, healthy.
Helps regulate the amount of calcium and phosphate in the body which in turn are needed to keep bones and teeth healthy.
Helps to maintain cell structure by protecting cell membranes.
Is needed for blood clotting, which means it helps wounds heal properly. There is increasing evidence that vitamin K is also needed to help build strong bones.