Vitamin

Can a more precise definition of Vitamin be given, in order that can distinguish from other organic molecules required by organisms?Rick Swarts 00:34, 6 June 2006 (UTC)

A vitamin is an organic molecule required by a living organism in minute amounts for proper health. An organism deprived of all sources of a particular vitamin will eventually suffer from disease symptoms specific to that vitamin.

Vitamins can be classified as either water soluble, which means they dissolve easily in water, or fat soluble, which means they are absorbed through the intestinal tract with the help of lipids.

For many of us, the word "vitamin" conjures up the image of bottles of pills lining the shelves of the local drugstore, or perhaps the fortified cereals that we eat for breakfast each morning. But these chemical substances occur naturally, in minute quantities, in most of the foods that we eat and, for the most part, we rely on ffood sources to meet our vitamin needs. However, there are a few vitamins that we obtain by other means: for example, microorganisms in the intestine - commonly known as gut flora - produce vitamin K and biotin, which one form of vitamin D is synthsized in the skin with the help of natural ultraviolet sunlight.

In general, an organism must obtain vitamins or their metabolic precursors from outside the body, most often from the organism's diet. Examples of vitamins that the human body can derive from precursors include vitamin A, which can be produced from beta carotene; niacin from the amino acid tryptophan; and vitamin D through exposure of skin to ultraviolet light.

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 merely promote health, but are not strictly essential.

The word vitamine was coined by the Polish biochemist Casimir Funk in 1912. Vita in Latin is life and the -amine suffix is for amine; at the time it was thought that all vitamins were amines. This is now known to be incorrect.

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 in which collagen is not properly formed, and characterized by poor wound healing, bleeding of the gums, and severe pain. In 1753, Lind published his Treatise on the Scurvy. His recommendation of using lemons and limes to avoid scurvy was adopted by the British Royal Navy, resulting in the nickname Limey for sailors of that organization. His discovery, however, was not widely accepted by individuals; In the Royal Navy's Arctic expeditions in the 19th century, for example, it was widely believed that scurvy was prevented by good hygiene on board ship, regular exercise, and maintaining the morale of the crew, rather than by a diet of fresh food, so that Navy expeditions took all the amenities of 'sophisticated' society, like silk sheets, spices, expensive food and drink, and almost nothing of any use beyond the Arctic Circle. As a result, these expeditions continued to be plagued by scurvy and other deficiency diseases. At the time Robert Falcon Scott made his two expeditions to the Antarctic in the early 20th century, the prevailing medical theory was that scurvy was caused by "tainted" canned food.

In 1881, Russian surgeon Nikolai Lunin fed mice upon an artificial mixture of all the separate constituents of milk known at that time, namely the proteins, fats, carbohydrates, and salts. They died, while the mice fed by milk itself developed normally. He made a conclusion that "a natural food such as milk must therefore contain besides these known principal ingredients small quantities of unknown substances essential to life" [1] However, his conclusion was rejected by other researchers who were unable to reproduce his results. One difference was that he used table sugar (sucrose), while other researchers used milk sugar (lactose) which still contained small amounts of vitamin B.

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 are necessary to the human body. When Casimir Funk isolated the water-soluble complex of micronutrients whose bioactivity 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 already 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.

The reason the alphabet soup of vitamins seems to skip from E to the rarely-mentioned K is that most of the "letters" were reclassified, as with fatty acids, discarded as false leads, or renamed because of their relationship to "vitamin B", which became a "complex" of vitamins. Vitamin G, Riboflavin, for example, is now known as B₂.

Throughout the early 1900s, scientists were able to isolate and identify a number of vitamins by depriving animals of them. Initially, lipid from fish oil was used to cure rickets in rats, and the fat-soluble nutrient was called "antirachitic A". The irony here is that the first "vitamin" bioactivity ever isolated, which cured rickets, was initially called vitamine A, this bioactivity is now called vitamin D, which is subject to the semantic debate that vitamin D is not truly a vitamin because it is a steroid derivative. What we now call "vitamin A" was identified in fish oil because it was inactivated by ultraviolet light. Most of what we now recognize as the water-soluble organic micronutrients were initially referred to as just one entity, "vitamin B".

Human vitamins

In humans, there are thirteen vitamins, divided into two groups, the four fat-soluble vitamins (A, D, E and K) and the nine water-soluble vitamins (eight B vitamins and vitamin C).

Vitamin name	Chemical name	Solubility	Deficiency disease	Overdose	Estimated Average Minimum Daily Requirement (male, aged 19–30)
Vitamin A	Retinol	Fat	Night-blindness, Keratomalacia	7.5 mg	620 μg
Vitamin B1	Thiamine	Water	Beriberi	n/a	1000 μg
Vitamin B2 (G)	Riboflavin	Water	Ariboflavinosis	n/a	1100 μg
Vitamin B3 (PP)	Niacin	Water	Pellagra	2500 mg	12000 μg
Vitamin B5	Pantothenic acid	Water	Paresthesia	n/a	10000 μg
Vitamin B6	Pyridoxine	Water	n/a	400 mg	1100 μg
Vitamin B7 (H)	Biotin	Water	n/a	n/a	30 µg
Vitamin B9 (M)	Folic acid	Water		1 mg	320 μg
Vitamin B12	Cyanocobalamin	Water	Pernicious anemia	n/a	2 µg
Vitamin C	Ascorbic acid	Water	Scurvy	n/a	75000 μg
Vitamin D1–D4	Lamisterol, Ergocalciferol, Calciferol, Dihydrotachysterol, 7-dehydrositosterol	Fat	Rickets	1.25 mg	2 µg (for all Vitamin D)
Vitamin E	Tocopherol	Fat	n/a	33000 mg	12000 μg
Vitamin K	Naphthoquinone (not to be confused with Ketamine)	Fat	Bleeding diathesis	n/a	75 µg

NUTRITION

Why we need vitamins

Although vitamins contain no calories, they are essential for normal growth and development, and many chemical reactions in the body. Vitamins are necessary for the body to use the calories provided by the food that we eat and help process proteins, carbohydrates, and fats. Vitamins are also involved in building cells, tissues, and organs - vitamin C, for example, helps produce healthy skin.

Vitamins are classified as fat-soluble or water-soluble based on how they are absorbed by the body. Vitamins A, D, E, and K are fat soluble, while the water-soluble vitamins include vitamin c and the B-complex vitamins (thiamine (B1), ribonflavin (B2), niacin (B3), pantothenic acid (B5), vitamin B6, vitmain B12, biotin and folate.

Reasearch has shown that foods rich in antioxidants are particularly beneficial for health. Antioxidants neutralize free radicals. A buildup of free radicals can damage body cells and tissues, resulting in disease. Studies have shown that diets rich in vegetables and fruits result in a lower incidence of some diseases, including certain cancers.

Vitamin deficiencies

Deficiencies of vitamins are either primary or secondary. A primary deficiency occurs because you do not get enough of the vitamin in the food you eat. A secondary deficiency may be due to a lifestyle factor, such as smoking, excessive alchohol consumption, or the use of certain medications that interfere with the absorption or the body's use of the vitmain. Prolonged use of antibiotics will kill off the useful gut flora that make vitamin K. Vitamin deficiencies may also be due to an underlying problem, such as an intestinal disorder, that prevents or limits the absorption or use of the vitamin.

Well-known vitamin deficiencies are thiamine (beriberi), niacin (pellagra), vitamin C (scurvy) and Vitamin D (rickets). In north America today, however, such deficiencies are rare due to an adequate food supply for most people, and food fortification programs that add vitamins and minerals to common foods.

Scientists now have shifted their focus to discovering ways in which vitamins can promote health, prevent disease, boost the body's protection against infection and even slow down the aging process. At the same time, public interest in vitamins has heightened. This has been prompted by headlines in the media andwidespread advertising by the manufacturers of nutrient supplements.

Vitamin overdosing

The likelihood of consuming too much of any vitamin from food is remote, but overdosing from vitamin supplementation often occurs. For example, many people take large amounts of vitamin C, usually in the belief that this will relieve or "cure" a cold. However, overdosing on vitamin C can lead to diarrhea or kidney stones. If you take vitamin supplements, you should always do so at the advice of your doctor or dietitian, and first consider whether your diet could be improved instead.

Notes

Some of the vitamins are known by other names in older literature. These names are written after the vitamins in brackets. Vitamin B₂ is also referred to as vitamin G. Vitamin B₇, or biotin is also referred to as "vitamin H." Vitamin B₉, or folic acid and other folates such as "vitamin M" (monkey antianemia factor, pteryl-tri-glutamic acid) are referred to as folicin. Vitamin B₃ is also referred to as "vitamin PP", a name derived from the obsolete term "pellagra-preventing factor". Many other essential dietary substances were originally called vitamins and are now classified differently.

Other nutrients that are not classified as vitamins include carnitine (meat, fish, dairy), DMAE (fish, eggs, soy, brains), lipoic acid (liver), folinic acid (liver), bioptrin (fish, liver), PPQ (below) and coenzyme Q (meat, yogurt, soy).

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.
• Herbalists and naturopaths have named various therapedic chemicals "vitamins", even though they are not, including vitamin T, S-Methylmethionine (vitamin U) and vitamin X.
• 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, vitamin B₁₅; the related substance dimethylglycine is quite wrongly referred to as vitamin B₁₅ but also labeled B₁₆.
• The toxins laetrile and amygdaline are 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 and their claimed anticancer activities have been disproven by many experiments.
• Flavonoids are sometimes called vitamin P.
• Animal, bird, and bacterial growth factors have been designated vitamins such as para-aminobenzoic acid (PABA) which is the chicken feathering factor vitamin B₁₀, the folacin (see folic acid) pteryl-heptaglutamic acid is the chicken growth factor vitamin B₁₁ or vitamin Bc-conjugate and orotic acid as vitamin B₁₃ for rats.
• 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 (adenylic acid), but are no longer recognized as such.

Non-human vitamins

Different organisms need different trace organic substances. Most mammals need, with few exceptions, the same vitamins as humans. One notable exception is Vitamin C, which can be synthesized by all other mammals except other higher primates and guinea pigs. The less related a species is to mammals, the more different the organisms' requirements become. For example, some bacteria need adenine. Pyrroloquinoline quinone (PQQ) found in yogurt was reported as a vitamin for mice in 2003.

See also

• Nutrients
  • Dietary minerals
  • Essential amino acids
  • Nootropics (cognitive enhancers)
• Dietary supplement
• Illnesses related to poor nutrition
• Pharmacology
• Vitamin poisoning (overdose)

References

ISBN links support NWE through referral fees

• Stedman's Medical Dictionary. Ed. Maureen Barlow Pugh et.al. 27th ed. Baltimore: Lippincott Williams & Wilkins, 2000.
• Donatelle, Rebecca J. Health: The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.
• Funk, C. and H. E. Dubin. The Vitamines. Baltimore: Williams and Wilkins Company, 1922.
• The History of Vitamin Discovery. Retrieved 1 Feb 2005.
• Bellis, Mary. History of Vitamins. Retrieved 1 Feb 2005.
• Challem, Jack (1997). The Past, Present and Future of Vitamins. Retrieved 1 Feb 2005.
• Leonhardt, David (2004). Vitamin A - The Glow in the Dark Vitamin. Retrieved 1 Feb 2005.
• A Brief Update on Ubiquinone (Coenzyme Q10), Journal of Orthomolecular Medicine 2000; 15(2):63-68.

External links

• USDA RDA chart in PDF format
• The lab which discovered the enzyme associated with PQQ
• Health Canada Dietary Reference Intakes Reference Chart for Vitamins

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