Vitamin

Vitamins are organic chemicals that a given living organism requires in trace quantities for good health, but which the organism cannot synthesize, and therefore must obtain from its diet. The term vitamin does not encompass other essential nutrients such as dietary minerals, essential fatty acids or essential amino acids. Nor is it used for the large number of other nutrients that are merely health-furthering, but not strictly essential. Humans require 13 different vitamins.

The word vitamin was coined by the Polish biochemist Kazimierz Funk in 1912. Vita in Latin is life and the -amin suffix is short for amine; at the time it was thought that all vitamins were amines. Though this is now known to be incorrect, the name has stuck.

Contents

1 History 2 Human vitamins 2.1 Vitamin deficiency and excess 3 Pseudo-vitamins

History

The value of eating certain foods to maintain health was recognized long before vitamins were identified. The ancient Egyptians knew that feeding a patient liver would help cure night blindness, now known to be caused by a Vitamin A deficiency. In 1747, the Scottish surgeon James Lind discovered that citrus foods helped prevent scurvy, a particularly deadly disease characterized by bleeding and severe pain. In 1753, Lind published his Treatise on the Scurvy.

In 1905, William Fletcher discovered that eating unpolished rice instead of polished helped prevent the disease beriberi. The following year, Frederick Hopkins postulated that foods contained "accessory factors"—in addition to proteins, carbohydrates, fats, etc.—that were necessary to the human body. When Kazimierz Funk isolated the chemical that Fletcher had identified, he proposed that it be named "Vitamine". The name soon became synonymous with Hopkins' "accessory factors", and by the time it was shown that not all vitamins were amines, the word was ubiquitous. In 1920, Jack Cecil Drummond proposed that the final "e" be dropped, to deemphasize the "amine" reference, after the discovery that Vitamin C had no amine component, and the name has been "vitamin" ever since.

Throughout the early 1900s, scientists were able to isolate and identify a number of vitamins by depriving animals of them.

Human vitamins

Vitamin Name	Chemical Name	Solubility	Deficiency Disease
Vitamin A	Retinol	Fat	Night-blindness
Vitamin B1	Thiamine	Water	Beriberi
Vitamin B2	Riboflavin	Water	Ariboflavinosis
Vitamin B3	Niacin	Water	Pellagra
Vitamin B5	Pantothenic acid	Water	Paresthesias
Vitamin B6	Pyridoxine	Water
Vitamin B7	Biotin	Water
Vitamin B9	Folic acid	Water
Vitamin B12	Cyanocobalamin	Water	Pernicious anaemia
Vitamin C	Ascorbic acid	Water	Scurvy
Vitamin D1	Lamisterol	Fat	Rickets
Vitamin D2	Ergocalciferol	Fat	Rickets
Vitamin D3	Calciferol	Fat	Rickets
Vitamin D4	Dihydrotachysterol	Fat	Rickets
Vitamin D5	7-dehydrositosterol	Fat	Rickets
Vitamin E	Tocopherol	Fat
Vitamin K	Naphthoquinone	Fat

Vitamin deficiency and excess

An organism can survive for some time without vitamins, although prolonged vitamin deficit results in a disease state, often painful and potentially deadly. Body stores for different vitamins can vary widely; an adult may be deficient in Vitamins A or B₁₂ for a year or more before developing a deficiency condition, while Vitamin B₁ stores may only last a couple of weeks.

Fat-soluble vitamins may be stored in the body and can cause toxicity when taken in excess. Water-soluble vitamins are not stored in the body, with the exception of Vitamin B₁₂, which is stored in the liver.

Pseudo-vitamins

• Vitamin F was the designation originally given to essential fatty acids that the body cannot manufacture. They were "de-vitaminized" because they are fatty acids. Fatty acids are a major component of fats which, like water, are needed by the body in large quantities and thus do not fit the definition of vitamins which are needed only in trace amounts.
• Although there is no Vitamin S, the suggestion has been made that salicylic acid may qualify for the criteria needed to be defined as a vitamin, and that in this case the designation "Vitamin S" could be used to describe it.
• Herbalists and naturopaths have named various herbs and chemicals "vitamins", even though they are not, including Vitamin T and Vitamin U.
• Some authorities say that Ubiquinone, also called Coenzyme Q₁₀, is a vitamin. Ubiquinone is manufactured in small amounts by the body, like Vitamin D.
• Pangamic acid and the related substance dimethylglycine are sometimes referred to as Vitamin B₁₅.
• Laetrile is sometimes referred to as Vitamin B₁₇. Both pangamic acid and laetrile were first proposed as vitamins by Ernst T. Krebs; neither are recognized by the medical community as vitamins.
• Bioflavonoids are sometimes called Vitamin P.
• A few substances were once thought to be B-complex vitamins and are referred to as B-vitamins in older literature, including B₄ (Adenine) and B₈, but are no longer recognized as such.