Difference between revisions of "Vitamin" - New World Encyclopedia

From New World Encyclopedia
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Can a more precise definition of Vitamin be given, in order that can distinguish from other organic molecules required by organisms?[[User:Rick Swarts|Rick Swarts]] 00:34, 6 June 2006 (UTC)
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'''Vitamins''' are organic substances essential to human health.  They are [[enzymes]], complex [[proteins]] which act as [[catalyst]]s for temperature sensitive biological reactions.  Vitamins are also essential parts of [[hormones]].
  
 +
The term ''vitamin'' does not encompass other essential nutrients such as [[dietary mineral]]s, essential [[fatty acid]]s, or essential [[amino acid]]s, nor is it used for the large number of other nutrients that merely promote health, but are not strictly essential.
  
−
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]] [[symptom]]s specific to that vitamin.
+
==Types of Vitamins==
  
 
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 [[lipid]]s.
 
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 [[lipid]]s.
  
−
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.
 
−
 
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In general, an organism must obtain vitamins or their metabolic precursors from outside the body, most often from the organism's [[diet (nutrition)|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 nutrient]]s such as [[dietary minerals]], [[essential fatty acid]]s, or [[essential amino acid]]s, 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 [[Poland|Polish]] [[biochemistry|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 [[Egypt]]ians knew that feeding a patient [[liver]] would help cure [[night blindness]], now known to be caused by a [[vitamin A]] deficiency.  In [[1747]], the [[Scotland|Scottish]] [[surgery|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 [[gingiva|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" [[canning|canned food]].
 
−
 
−
In [[1881]], [[Russia]]n surgeon Nikolai Lunin fed [[mouse|mice]] upon an artificial mixture of all the separate constituents of [[milk]] known at that time, namely the [[protein]]s, [[fat]]s, [[carbohydrate]]s, and [[salt]]s.  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" [http://nobelprize.org/medicine/laureates/1929/hopkins-lecture.html]  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 [[amine]]s, 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 B<sub>2</sub>.
 
−
 
−
Throughout the early [[1900]]s, 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 [[rat]]s, 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).
 
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).
 
{| {{prettytable}}
 
{| {{prettytable}}
Line 127: Line 107:
 
| 75 µg
 
| 75 µg
 
|}
 
|}
 +
 +
 +
 +
== History ==
 +
The value of eating certain foods to maintain health was recognized long before vitamins were identified.  The ancient [[Egypt]]ians knew that feeding a patient [[liver]] would help cure [[night blindness]], now known to be caused by a [[vitamin A]] deficiency.  In [[1747]], the [[Scotland|Scottish]] [[surgery|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 [[gingiva|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" [[canning|canned food]].
 +
 +
In [[1881]], [[Russia]]n surgeon Nikolai Lunin fed [[mouse|mice]] upon an artificial mixture of all the separate constituents of [[milk]] known at that time, namely the [[protein]]s, [[fat]]s, [[carbohydrate]]s, and [[salt]]s.  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" [http://nobelprize.org/medicine/laureates/1929/hopkins-lecture.html]  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"&mdash;in addition to proteins, carbohydrates, fats, etc.&mdash;that are necessary to the human body.
 +
 
 +
When [[Casimir Funk]] in [[1912]] isolated the water-soluble complex of micronutrients whose bioactivity Fletcher had identified, he proposed that it be named "Vitamine".  ''Vita'' in Latin is ''life'' and the ''-amine'' suffix is for ''[[amine]]''; at the time it was thought that all vitamins were amines.  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 B<sub>2</sub>.
 +
 +
Throughout the early [[1900]]s, scientists were able to isolate and identify a number of vitamins by depriving animals of them.
  
 
==NUTRITION==
 
==NUTRITION==
 
===Why we need vitamins===
 
===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]].
+
Vitamins are not a source of energy nor a source of stuctural tissue components. They give living cells the ability to conduct and control chemical reactions.  They are essential for normal growth and development. 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.
  
−
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 if a person does not get enough of the vitamin in the food he eats. A secondary deficiency may be due to a lifestyle factor, such as smoking, excessive alcohol consumption, or the use of certain medications that interfere with the absorption or the body's use of the vitamin. 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.
  
−
===Vitamin deficiencies===
+
According to the World Health Organization vitamin A deficiency is the most serious vitamin deficiency disease in the world today. It is the leading cause of preventable childhood blindness in developing countries. It also increases the risk of death from measles, malaria, worms, and other diseases.  It can be prevented by diet improvements and supplementation for children and mothers.[http://www.wpro.who.int/health_topics/micronutrient_deficiencies/general_info.htm]
−
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.
 
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.
+
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 and widespread advertising by the manufacturers of nutrient supplements.
  
 
===Vitamin overdosing===
 
===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.
+
The likelihood of consuming too much of any vitamin from food is remote, but overdosing from vitamin supplementation can occur. 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 ===
 
−
<references />
 
−
 
 
−
Some of the vitamins are known by other names in older literature. These names are written after the vitamins in brackets.
 
−
[[B vitamins|Vitamin B<sub>2</sub>]] is also referred to as [[vitamin G]].
 
−
[[B vitamins|Vitamin B<sub>7</sub>]], or [[biotin]] is also referred to as "vitamin H."
 
−
[[B vitamins|Vitamin B<sub>9</sub>]], or [[folic acid]]  and other folates such as "vitamin M" (monkey antianemia factor, pteryl-tri-glutamic acid) are referred to as folicin.
 
−
[[B vitamins|Vitamin B<sub>3</sub>]] 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, [[egg]]s, [[soy]], [[brain]]s), [[lipoic acid]] ([[liver]]), [[folinic acid]] (liver), [[bioptrin]] (fish, liver), [[PPQ]] (below) and [[coenzyme Q]] (meat, [[yogurt]], soy).
 
  
 
=== Vitamin deficiency and excess ===
 
=== Vitamin deficiency and excess ===
Line 162: Line 146:
  
 
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 B<sub>12</sub>, which is stored in the [[liver]].
 
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 B<sub>12</sub>, which is stored in the [[liver]].
−
 
−
== Pseudo-vitamins ==
 
−
 
−
* ''Vitamin F'' was the designation originally given to [[essential fatty acid]]s that the body cannot manufacture. They were "de-vitaminized" because they are [[fatty acid]]s. Fatty acids are a major component of [[fat]]s 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 [[naturopath]]s 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 Q<sub>10</sub>, is a vitamin.  Ubiquinone is manufactured in small amounts by the body, like vitamin D.
 
−
* [[Pangamic acid]], vitamin B<sub>15</sub>; the related substance [[dimethylglycine]] is quite wrongly referred to as ''vitamin B<sub>15</sub>'' but also labeled B<sub>16</sub>.
 
−
* The toxins [[laetrile]] and amygdaline are sometimes referred to as ''vitamin B<sub>17</sub>''.  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 B<sub>10</sub>, the folacin (see [[folic acid]]) pteryl-heptaglutamic acid is the chicken growth factor vitamin B<sub>11</sub> or vitamin Bc-conjugate and orotic acid as vitamin B<sub>13</sub> for rats.
 
−
* A few substances were once thought to be B-complex vitamins and are referred to as B-vitamins in older literature, including B<sub>4</sub> ([[adenine]]) and B<sub>8</sub> ([[adenylic acid]]), but are no longer recognized as such.
 
−
 
−
== Non-human vitamins ==
 
−
 
−
Different organisms need different trace organic substances.  Most [[mammal]]s 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 pig]]s. 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==
 
−
* [[Nutrient]]s
 
−
** [[Dietary mineral]]s
 
−
** [[Essential amino acid]]s
 
−
** [[Nootropic|Nootropics (cognitive enhancers)]]
 
−
* [[Dietary supplement]]
 
−
* [[Illnesses related to poor nutrition]]
 
−
* [[Pharmacology]]
 
−
* [[Vitamin poisoning|Vitamin poisoning (overdose)]]
 
  
 
==References==
 
==References==
Line 197: Line 156:
 
* Leonhardt, David (2004). [http://www.theallineed.com/health/04111401.htm Vitamin A - The Glow in the Dark Vitamin]. Retrieved 1 Feb 2005.
 
* Leonhardt, David (2004). [http://www.theallineed.com/health/04111401.htm Vitamin A - The Glow in the Dark Vitamin]. Retrieved 1 Feb 2005.
 
* [http://faculty.washington.edu/ely/JOM5.html A Brief Update on Ubiquinone (Coenzyme Q10), Journal of Orthomolecular Medicine 2000; 15(2):63-68.]
 
* [http://faculty.washington.edu/ely/JOM5.html A Brief Update on Ubiquinone (Coenzyme Q10), Journal of Orthomolecular Medicine 2000; 15(2):63-68.]
 +
*Murray, R., Granner, K., et al, ''Harper's Illustrated Biochemistry'' 26th Edition, New York : Lange Medical Books 2003 ISBN 0071389016
  
 
==External links==
 
==External links==

Revision as of 03:52, 16 July 2006

Vitamins are organic substances essential to human health. They are enzymes, complex proteins which act as catalysts for temperature sensitive biological reactions. Vitamins are also essential parts of hormones.

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.

Types of Vitamins

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.

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)[1]
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 [2] 1 mg 320 μg
Vitamin B12 Cyanocobalamin Water Pernicious anemia n/a 2 µg
Vitamin C[3] 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


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 in 1912 isolated the water-soluble complex of micronutrients whose bioactivity Fletcher had identified, he proposed that it be named "Vitamine". Vita in Latin is life and the -amine suffix is for amine; at the time it was thought that all vitamins were amines. 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.

NUTRITION

Why we need vitamins

Vitamins are not a source of energy nor a source of stuctural tissue components. They give living cells the ability to conduct and control chemical reactions. They are essential for normal growth and development. 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 deficiencies

Deficiencies of vitamins are either primary or secondary. A primary deficiency occurs if a person does not get enough of the vitamin in the food he eats. A secondary deficiency may be due to a lifestyle factor, such as smoking, excessive alcohol consumption, or the use of certain medications that interfere with the absorption or the body's use of the vitamin. 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.

According to the World Health Organization vitamin A deficiency is the most serious vitamin deficiency disease in the world today. It is the leading cause of preventable childhood blindness in developing countries. It also increases the risk of death from measles, malaria, worms, and other diseases. It can be prevented by diet improvements and supplementation for children and mothers.[2]

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 and widespread 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 can occur. 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.

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.

References
ISBN links support NWE through referral fees

External links


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  1. ↑ " Dietary Reference Intakes", Health Canada. (retrieved May 4, 2006)
  2. ↑ Folic acid (vitamin B9) deficiency in pregnant women is associated with birth defects, and has links to cancer as well.
  3. ↑ Vitamin C is sometimes considered a macronutrient rather than a vitamin.
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