The term vitamin is derived from the words vital and amine, because vitamins are required for life and were originally thought to be amines. Although not all vitamins are amines, they are organic compounds required by humans in small amounts from the diet. An organic compound is considered a vitamin if a lack of that compound in the diet results in overt symptoms of deficiency.
Vitamins are essential, meaning that our body can not produce them itself. We need to supply them daily in our diet or through supplements. Each vitamin fulfills its unique function in the metabolism.
You need only small amounts (that's why they are often referred to as micronutrients) because the body uses them without breaking them down, as happens to carbohydrates and other macronutrients. So far, 13 compounds have been classified as vitamins. Vitamins A, D, E, and K, the four fat-soluble vitamins, tend to accumulate in the body. Vitamin C and the eight B vitamins-biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin B12-dissolve in water, so excess amounts are excreted.

The "letter" vitamins sometimes go by different names. These include:
  • Vitamin A = retinol, retinaldehyde, retinoic acid

  • Vitamin B1 = thiamin

  • Vitamin B2 = riboflavin

  • Vitamin B3 = niacin

  • Vitamin B5 = pantothenic acid

  • Vitamin B6 = pyridoxine, pyridoxal, pyridoxamine

  • Vitamin B9 = folic acid
  • Vitamin B12 = cobalamin

  • Vitamin C = ascorbic acid

  • Vitamin D = calciferol

  • Vitamin E = tocopherol, tocotrienol

  • Vitamin H = biotin

  • Vitamin K = phylloquinone
  • Vitamin A

    Vitamin A is commonly known as the anti-infective vitamin, because it is required for normal functioning of the immune system. Vitamin A also helps you to see in the dark, it stimulates the production and activity of white blood cells, takes part in remodeling bone, helps maintain the health of endothelial cells (those lining the body's interior surfaces), and regulates cell growth and cell division.
    Basically vitamin A is available in two main forms; as Retinol, which is the actual vitamin, and as b-carotene that can be utilised in an animal’s body in the production of vitamin A (Retinol).

    Vitamin B1

    Vitamin B1, otherwise known as thiamine, is necessary for most every cellular reaction in the body as a participant in an enzyme system known as thiamin pyrophosphate. It is vital to normal functioning of the nervous system and metabolism. It can be found in meat, whole grains, fish, and nuts.
    Vitamin B1 supports normal growth and development of the body, it supports the working of the nervous system, heart and muscles. It restores deficiencies caused by alcoholism, cirrhosis, overactive thyroid, infection, breastfeeding, absorption diseases, pregnancy, prolonged diarrhea, and burns. And it can reduce depression, fatigue and motion sickness.

    Vitamin B2

    Vitamin B2 is a water-soluble B-complex vitamin, also known as Riboflavin.
    Riboflavin is important to energy metabolism (processing nutrients like protein, fat, carbohydrate and alcohol that have calories to a form of energy that the body can use - ATP), normal growth, bloodcel development,nerve development, regulation of certain hormones, normal eyesight and healthy skin.
    Foods high in riboflavin are milk, yogurt, cheeses, meat, leafy green vegetables, whole and enriched grains. Riboflavin is an essential vitamin and is easily destroyed by light. Oral contraceptives may cause a riboflavin deficiency as well.

    Vitamin B3

    Vitamin B3, Otherwise known as niacin, acts like other B vitamins to create enzymes that are essential to metabolic cell activity, synthesize hormones, repair genetic material, decreases cholesterol and triglycerides in blood, and maintain normal functioning of the nervous system. Great sources of this vitamin may be found in meat, fish, and whole grains.

    Vitamin B5

    Vitamin B5 otherwise known as pantothenic acid, is essential to all forms of life. Pantothenic acid is found throughout living cells in the form of coenzyme A (CoA), a vital coenzyme in numerous chemical reactions like the energy metabolism of carbohydrates, protein, and fat. It also helps in, the growth and development of the body, healing of wounds in animals, relieving stress and lessen fatigue.
    Great sources of this vitamin include eggs, nuts, and whole-wheat products.

    Vitamin B6

    Vitamin B6, otherwise known as pyridoxine, is a water-soluble vitamin that was first isolated in the 1930's. There are six forms of vitamin B6: pyridoxal (PL), pyridoxine (PN), pyridoxamine (PM), and their phosphate derivatives: pyridoxal 5'-phosphate (PLP), pyridoxine 5'-phosphate (PNP), and pridoxamine 5'-phospate (PNP). PLP is the active coenzyme form, and has the most importance in human metabolism.

    Vitamin B6 performs as a coenzyme to carry out metabolic processes that affect the body’s use of protein, carbohydrates, and fat. It helps to convert tryptophan to niacin.

    Vitamin B6 must be obtained from the diet because humans cannot synthesize it, it may be found in meat, fish, eggs, milk, and whole grain foods.

    Vitamin B9

    Vitamin B9, otherwise known as folic acid, serves as a coenzyme during the creation of DNA. This vitamin is also very important to the growth and reproduction of all body cells, including red blood cells. Great food sources of vitamin B-9 include liver and dark green leafy vegetables

    Vitamin B12

    Vitamin B12 is also known as cobolamin. Cobolamin is needed in the manufacture of red blood cells and the maintenance of red blood cells and it stimulates appetite, promotes growth and release energy. It is often used with older people to give an energy boost, assist in preventing mental deterioration and helps with speeding up thought processes.This vitamin is also used in the metabolism of fats, proteins and carbohydrates.
    Vitamin B12 is present in liver, organ meat, muscle meat, shellfish, eggs, cheese, fish, and can be manufactured in the body. Although milk contains B12, processing of milk may lead to destruction of the vitamin.

    Vitamin C

    Vitamin C is a water-soluble vitamin used by the body for several purposes. Most animals can synthesize their own vitamin C, but some animals, including guinea pigs, humans, and other primates, cannot.

    Vitamin C is one of the most crucial vitamins in your body for the very fact that plays a large role in hundreds of the body’s functions.

    The most plentiful tissue in the body is collagen, which is a connective tissue. The primary role of Vitamin C is to help this connective tissue. Because collagen is the defense mechanism against disease and infection, and because Vitamin C helps build collagen, it makes sense that it is also a remedy for scurvy by contributes to hemoglobin production. It promotes the production of red-blood-cell in bone marrow. Ascorbic Acid also supports healthy capillaries, gums, teeth, and even helps heal wounds, burns, and broken tissues. It contributes to hemoglobin and red-blood-cell production in bone marrow while even preventing blood clots. The list goes on. It helps heal urinary-tract infections, and helps treat anemia.

    Another large benefit of this vitamin is the fact that it plays a large role in the production of antibodies. When the immune system is being overworked, for example when a cold strikes or when your body is wounded, Vitamin C comes in to play by beefing up the white blood cell count and function. It also functions as a promoter of interferon, a compound that fights cancer. An example of this would be blocking production of nitrosamines which are thought to be carcinogenic

    You can find this Vitamin in fruits, grapefruit, guava, lemons, mangos, orange juice, tomatoes, strawberries, vegetables, black currants, brussels sprouts, etc.

    Vitamin D

    Vitamin D, otherwise known as the sunshine vitamin, is significant in normal body growth and development. In particularly, vitamin D is used to absorb calcium and phosphorus to create bones and teeth. It also helps assisting in a healthy heart and nervous system. In some recent studies it has also shown great promise in assisting psoriasis, the immune system, thyroid function as well as normal blood clotting.It also promotes normal cell growth and maturation, it prevents rickets, treats low blood calcium with patients with kidney disease and it is a potential reduction in breast and colon cancer.
    Great sources of this supplement include sunlight, fortified milk, oily fish, liver, and eggs.

    Vitamin E

    Vitamin E, otherwise known as alpha-tocopherol, serves as a cofactor in several enzyme systems. It helps to protect fats, cell membranes, DNA, and enzymes against damage, it encourages normal growth and development, it helps to prevent vitamin E deficiency in premature infants and those with low birth weights, it acts as an antioxidant to protect against heart disease and cancer, it improves the immune system and it reduces the risk of a first fatal heart attack in men.

    Vitamin E is also an important factor for reproduction success with reptiles. This vitamin is especially important in the forming of eggs and the strength and shape of the young that is to grow in it.

    Great sources of vitamin E may be found in wheat germ, nuts and seeds, whole grain cereals, eggs, and leafy greens.

    Vitamin H

    Vitamin H, otherwise known as biotin, is essential to, normal growth, development and overall health. It also reduces symptoms of zinc deficiency, it helps in the formation of fatty acids and it could relieve muscle pain and depression.
    It plays a special role in enabling the body to use blood sugar (glucose), a major source of energy for body fluids. Biotin also helps produce certain enzymes.
    Bacteria in the intestines produce enough biotin for the body so that most people would not need an additional supplement of vitamin H.
    However, additional great sources of vitamin H are found in egg yolks, fish, nuts, oatmeal,chicken, cheese, peas bananas and beans.

    Vitamin K

    Vitamin K, otherwise known as phytonadione, promotes production factors critical to normal blood clotting. It is also involved in bone formation and repair. In the intestines it also assists in converting glucose to glycogen, this can then be stored in the liver. There are some indications that Vitamin K may decrease the incidence or severity of osteoporosis and slow bone loss.
    When foods are processed or cooked, very little of vitamin K contained in foods is lost. Great sources of this vitamin include dark leafy greens, oils from green plants, and some dairy products.