Nutrition 101 - Glossary - V
Vitamin A Definition -Vitamin A is a fat-soluble vitamin that is found as either preformed vitamin A, present in animal products, or pro-vitamin A, found in fruits and vegetables; the most common type of pro-vitamin A is beta carotene. Relevance - Vitamin A support health of the skin, teeth, membranes, vision and soft and skeletal tissue; the active form of vitamin A is retinol, which is found in animal liver and whole milk, as well as some fortified foods.
Vitamin B12 Definition - Vitamin B12 is a water-soluble vitamin that supports the nervous system, DNA synthesis, and blood cells. Relevance - Absorbing B12 from food is a two-step process that occurs in the stomach that is impaired for individuals with pernicious anemia; vitamin B12 is found in meat, dairy, fish, shellfish, eggs and some fortified cereals.
Vitamin C Definition - Vitamin C is a water-soluble vitamin found in many fruits and vegetables that is important for tissue growth and repair and like most water-soluble vitamins, is not produced in the body. Relevance - Vitamin C is an antioxidant that must be obtained from the diet that, contrary to popular belief, has been shown to be largely ineffective in reducing the risk of the common cold; although it may shorten the duration of a cold.
Vitamin D Definition - Vitamin D is a fat-soluble vitamin that is stored in body fat; vitamin D aids in the absorption of calcium and protects against osteoporosis and rickets. Relevance - Few foods naturally contain vitamin D, mainly fatty fish, eggs, cheese and beef liver, so it is highly fortified in the diet; vitamin D is produced by the body during direct exposure to sunlight.
Vitamin E Definition - Vitamin E is the pooled name for eight naturally-occurring fat-soluble antioxidant compounds, of which alpha-tocopherol is the only one known to meet human needs. Relevance - Vitamin E acts as an antioxidant by prohibiting the formation of free-radicals during fat breakdown, but is also involved in immunity and cell signaling. The best sources of vitamin E include nuts, seeds, vegetable oils, fortified cereals and green leafy vegetables.
Vitamin K Definition - Vitamin K is a fat-soluble vitamin found in dark berries and green vegetables that makes proteins critical for proper blood clotting. Relevance - Vitamin K is typically administered by shot to newborns because they have very little, although deficiency is otherwise rare. Vitamin K is also critical for using calcium to build bones, and evidence shows that vitamin K improves bone health.