Vitamins A, D, E and K are fat-soluble vitamins. They are found in foods that contain fats and oils. For example Vitamin A can be obtained by eating fat-containing dairy products and liver. Limited amounts of Vitamin D are provided by consumption of dairy products and egg yolks. Vegetable oils contain Vitamin E. Fat soluble fats are absorbed in the intestine and stored in the body.
The water-soluble vitamins, Vitamin B and Vitamin C, cannot be stored by the body. The water-soluble vitamins are absorbed directly into the blood stream. During one 24-hour period, if a person consumes more Vitamin B or more Vitamin C than he or she needs, that person has no way to store the unused vitamins. Those excess vitamins are lost in the sweat or the urine. Water-soluble vitamins must be included in the daily diet, so that used and lost vitamins can be replaced every 24 hours.
Some Vitamin K comes from ingested food, and some comes from the intestine, where it is produced by intestinal bacteria. A large portion of the body’s needed Vitamin D comes from sunshine. Technically, an inactive form of Vitamin D is manufactured in the skin upon its exposure to sunlight. That inactive vitamin is then activated in the liver and kidney.