A vitamin is an organic compound required as a nutrient in tiny amounts by an organism.The term ‘vitamin’ first became popular in the early 1800s as a portmanteau of the words ‘vital’ and ‘mineral’, though the actual meaning of the word has developed somewhat since that time. A compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and the particular organism. For example, ascorbic acid functions as vitamin C for some animals but not others, and vitamins D, K and biotin are required in the human diet only in certain circumstances.The term vitamin does not include other essential nutrients such as dietary minerals, essential fatty acids, or essential amino acids, nor does it encompass the large number of other nutrients that promote health but are otherwise required less often.
There are two types of vitamins: fat soluble and water soluble. When you eat foods that contain fat-soluble vitamins, the vitamins are stored in the fat tissues in your body and in your liver. They wait around in your body fat until your body needs them.
Fat-soluble vitamins are happy to stay stored in your body for awhile — some stay for a few days, some for up to 6 months! Then, when it’s time for them to be used, special carriers in your body take them to where they’re needed. Vitamins A, D, E, and K are all fat-soluble vitamins.
Water-soluble vitamins are different. When you eat foods that have water-soluble vitamins, the vitamins don’t get stored as much in your body. Instead, they travel through your bloodstream. Whatever your body doesn’t use comes out when you urinate (pee).
So these kinds of vitamins need to be replaced often because they don’t stick around! This crowd of vitamins includes vitamin C and the big group of B vitamins — B1 (thiamin), B2 (riboflavin), niacin, B6 (pyridoxine), folic acid, B12 (cobalamine), biotin, and pantothenic acid.
Vitamins are classified by their biological and chemical activity, not their structure. Thus, each “vitamin” may refer to several vitamer compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals are grouped under an alphabetized vitamin “generic descriptor” title, such as “vitamin A”, which includes the compounds retinal, retinol, and four known carotenoids. Vitamers by definition are convertable to the active form of the vitamin in the body, and are sometimes inter-convertable to one another as well.
Vitamins have diverse biochemical functions. Some have hormone-like functions as regulators of mineral metabolism (e.g. vitamin D), or regulators of cell and tissue growth and differentiation (e.g. some forms of vitamin A). Others function as antioxidants (e.g. vitamin E and sometimes vitamin C). The largest number of vitamins (e.g. B complex vitamins) function as precursors for enzyme cofactor bio-molecules (coenzymes), that help act as catalysts and substrates in metabolism. When acting as part of a catalyst, vitamins may be tightly bound to enzymes as part of prosthetic groups: for example, biotin is part of enzymes involved in making fatty acids. Vitamins may also be less tightly bound to enzyme catalysts as coenzymes, detachable molecules which function to carry chemical groups or electrons between molecules. For example, folic acid carries various forms of carbon group – methyl, formyl and methylene – in the cell. Although these roles in assisting enzyme reactions are vitamins’ best-known function, the other vitamin functions are equally important.
Until the 1900s, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) can alter the types and amounts of vitamins ingested. Vitamins have been produced as commodity chemicals and made widely available as inexpensive pills for several decades, allo
wing supplementation of the dietary intake.
Vitamin A
Benefits:
Vitamin A prevents eye problems, promotes a healthy immune system, is essential for the growth and development of cells, and keeps skin healthy.
Sources:
Good sources of vitamin A are milk, eggs, liver, fortified cereals, darkly colored orange or green vegetables (such as carrots, sweet potatoes, pumpkin, and kale), and orange fruits such as cantaloupe, apricots, peaches, papayas, and mangos.
Quantity:
Teen guys need 900 micrograms of vitamin A each day.
Teen girls need 700 micrograms each day. It is possible to get too much vitamin A, so be careful with supplements. Don’t take vitamin A supplements If you’re taking isotretinoin (such as Accutane) for acne or other skin problems.
Oral acne medicines are vitamin A supplements, and a continued excess of vitamin A can build up in the body, causing headaches, skin changes, or even liver damage.
Vitamin B1 (Thiamin)
Benefits:
Thiamin helps the body convert carbohydrates into energy and is necessary for the heart, muscles, and nervous system to function properly.
Sources:
People get thiamin from many different foods, including fortified breads, cereals, and pasta; meat and fish; dried beans, soy foods, and peas; and whole grains like wheat germ.
Quantity:
Teen guys need 1.2 mg of thiamin each day; teen girls need 1 mg.
Vitamin B2 (Riboflavin)
Benefits:
Riboflavin is essential for turning carbohydrates into energy and producing red blood cells. It is also important for vision.
Sources:
Some of the best sources of riboflavin are meat, eggs, legumes (like peas and lentils), nuts, dairy products, green leafy vegetables, broccoli, asparagus, and fortified cereals.
Quantity:
Teen guys need 1.3 mg of riboflavin per day and teen girls need 1 mg.
Vitamin B3 (Niacin)
Benefits:
Niacin helps the body turn food into energy. It helps maintain healthy skin and is important for nerve function.
Sources:
You’ll find niacin in red meat, poultry, fish, fortified hot and cold cereals, and peanuts.
Quantity:
Teen guys need 16 mg of niacin daily. Teen girls need 14 mg a day.
Vitamin B6
Benefits:
Vitamin B6 is important for normal brain and nerve function. It also helps the body break down proteins and make red blood cells.
Sources:
A wide variety of foods contain vitamin B6, including potatoes, bananas, beans, seeds, nuts, red meat, poultry, fish, eggs, spinach, and fortified cereals.
Quantity:
Teen guys need 1.3 mg of vitamin B6 daily and teen girls need 1.2 mg.
Vitamin B9 (Folate)
Benefits:
Folate helps the body make red blood cells. It is also needed to make DNA.
Sources:
Liver, dried beans and other legumes, green leafy vegetables, asparagus, and orange juice are good sources of this vitamin. So are fortified bread, rice, and cereals.
Quantity:
Teen girls and guys need 400 micrograms of folate daily.
Vitamin B12
Benefits:
Vitamin B12 helps to make red blood cells, and is important for nerve cell function.
Sources:
Vitamin B12 is found naturally in fish, red meat, poultry, milk, cheese, and eggs. It’s also added to some breakfast cereals.
Quantity:
Teens should get 2.4 micrograms of vitamin B12 daily.
Vitamin C
Benefits:
Vitamin C is needed to form collagen, a tissue that helps to hold cells together. It’s essential for healthy bones, teeth, gums, and blood vessels. It helps the body absorb iron and calcium, aids in wound healing, and contributes to brain function.
Sources:
You’ll find high levels of vitamin C in red berries, kiwi, red and green bell peppers, tomatoes, broccoli, spinach, and juices made from guava, grapefruit, and orange.
Quantity:
Teen guys need 75 mg (milligrams; 1 milligram equals 1,000 micrograms) and girls need 65 mg of vitamin C a day.
Vitamin D
Benefits:
Vitamin D strengthens bones because it helps the body absorb bone-building calcium.
Sources:
This vitamin is unique — your body manufactures it when you get sunlight on your skin! You can also get vitamin D from egg yolks, fish oils, and fortified foods like milk.
Quantity:
Teens need 10 micrograms (400 IU) of vitamin D from food or supplements every day. Ask your doctor if supplements are right for you.
Vitamin
E
Benefits:
Vitamin E is an antioxidant and helps protect cells from damage. It is also important for the health of red blood cells.
Sources:
Vitamin E is found in many foods, such as vegetable oils, nuts, and green leafy vegetables. Avocados, wheat germ, and whole grains are also good sources.
Quantity:
Teen guys and girls need 15 mg of vitamin E every day.
