Did You Know Just That Many Cancers Are Linked To A Vitamin Deficiency?
Vitamin
From Wikipedia, the free encyclopedia
(Redirected from Vitamins)
Jump to: navigation, search
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 food 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.
Contents
1 History
2 Human vitamins
3 Nutrition
o 3.1 Why we need vitamins
o 3.2 Vitamin deficiencies
o 3.3 Vitamin overdosing
o 3.4 Notes
o 3.5 Vitamin deficiency and excess
4 Pseudo-vitamins
5 Non-human vitamins
6 See also
7 References
8 External links 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 1930)[1]Vitamin A
Retinol
Fat
Night-blindness, Keratomalacia
7.5 mg
620 µgVitamin 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 D1D4
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, vitamin 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
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.
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
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
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.
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.
An antitumor pterin phosphate named Vitamin B-14 by Norris
but latter abandoned by him as further evidence did not
comfirm this. (Norris claimed it was not Xanthopterin labled
B14 in France)
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
o Dietary minerals
o Essential amino acids
o Nootropics (cognitive enhancers)
Dietary supplement
Illnesses related to poor nutrition
Pharmacology
Vitamin poisoning (overdose)
References
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.
http://en.wikipedia.org/
wiki/Vitamins
Vitamin
