What are Fat-Soluble Vitamins? The Differences Between Fat-Soluble and Water-Soluble Vitamins
What is the difference between fat-soluble and water-soluble vitamins?
Vitamins are generally classified into two groups: fat-soluble vitamins and water-soluble vitamins. The fat-soluble vitamins are vitamins A,D, E, and K, and are stored in body fat and reach toxic levels. Water-soluble vitamins are B-complex vitamins and vitamin C. The water-soluble vitamins are generally not stored in any significant amounts in the body, so they need to be included in the diet on a daily basis. In healthy individuals, deficiencies in fat-soluble vitamins are more rare than deficiencies in water-soluble vitamins.
The absorption of fat-soluble vitamins in enhanced by dietary fat. Individuals who are afflicted with malabsorption of fat or who consume an extremely small amount of fat are at higher risk for development of fat-soluble vitamin deficiencies. Fat-soluble vitamins are generally more stable than water-soluble vitamins and are less prone to destruction by heat, air, and light.
Fat-soluble vitamins are vitamins A, D, E, and K. They are stored in the fatty tissue of the body and are more stable than their water-soluble cousins.
Vitamin A can be found in two forms: carotene and vitamin A. Preformed (or retinol). Carotene is found in dark, leafy green vegetables and deep orange vegetables (with the exception of oranges). Retinol is found in in animal products such as liver, milk fat in whole milk and cream, butter, and egg yolks.
Although it is necessary to ingest meat to obtain retinol, carotene is processed into vitamin A in the liver, which means that vegans and vegetarians are in no danger of forming a vitamin A deficiency so long as they include dark leafy green and dark orange vegetables in their diet.
Vitamin A Deficiency
Vitamin A is important for healthy epithelial tissue, which is the external skin and internal lining of the respiratory and gastrointestinal tract. A deficiency in vitamin A can therefor impair the intestinal tracts ability to absorb nutrients by flattening the villi. It increases the risk of infection and has been associated with night blindness in many countries. Vitamin A helps with bone growth, a healthy immune system, improved vision, and reproduction. A rare cause of hypocalcemia, or excess calcium in blood, has been associated with an excess of vitamin A.
Vitamin D has many physiological roles beyond those related to bones, including regulating blood pressure and acting as a tumor suppressant. It aids in the absorption of calcium and phosphorus, regulates the blood levels of calcium, and promotes bone and teeth mineralization.
Vitamin D Deficiency:
Vitamin D deficiency leads to secondary hyperparathyroidism, increased bone turnover, bone loss, and when severe, osteomalacia. Hypovitaminosis D is a condition of low vitamin D status, and is associated with impaired neuromuscular function. Hypovitaminosis D is prevalent even in southern latitudes that have increased sun exposure, and should be taken into account in the evaluation of postmenopausal and male osteoporosis.
Vitamin D deficiency can also lead to problems with muscle function, and has been associated with tuberculosis , rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases, hypertension, diabetes, and specific types of cancers.