7.2: Fat Soluble Vitamins
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Now that you know the basics of what vitamins are, let's talk about the Fat Soluble Vitamins (FSV's) specifically. There are only four FSV's: Vitamin A, Vitamin D, Vitamin E and Vitamin K. What makes them "fat soluble" is the fact that they dissolve in fats and oils but they won't dissolve in water. If you've ever seen a vitamin E capsule, you already know that inside the capsule is an oily substance containing vitamin E. The Fat soluble vitamins are present in many foods but they are especially high in foods like nuts and seeds that contain a high concentration of fats and oils. Though we will discuss each fat soluble vitamin separately, please keep in mind that in whole foods there are a variety of vitamins and minerals and other nutrients all working together. This is thought to be the reason that whole foods do such good things for the body whereas taking individual supplements doesn't usually benefit health and sometimes can be harmful. Many scientists and doctors (myself included) believe that it is the harmony of the nutrients coming in together that benefits our health and when we isolate an individual nutrient it cannot give the same benefits.
- 7.2A: Vitamin A
- Vitamin A is a fat-soluble vitamin that is stored in the liver. There are two types of vitamin A that are found in the diet. Preformed vitamin A is found in animal products such as meat, fish, poultry and dairy foods. Pro-vitamin A is found in plant-based foods such as fruits and vegetables. The most common type of pro-vitamin A is beta-carotene. Vitamin A is also available in dietary supplements.
- 7.2B: Vitamin D
- Vitamin D refers to a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol). Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements
- 7.2C: Vitamin E
- Vitamin E refers to a group of compounds that include both tocopherols and tocotrienols. Of the many different forms of vitamin E, γ-tocopherol is the most common form found in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine, and dressings. α-tocopherol, the most biologically active form of vitamin E, is the second-most common form of vitamin E in the diet.
- 7.2D: Vitamin K
- Vitamin K is a group of structurally similar, fat-soluble vitamins the human body requires for complete synthesis of certain proteins that are prerequisites for blood coagulation and which the body also needs for controlling binding of calcium in bones and other tissues. The vitamin K-related modification of the proteins allows them to bind calcium ions, which they cannot do otherwise. Without vitamin K, blood coagulation is seriously impaired.