:''For the similarly spelled nucleic acid, see
Thymine''
'Thiamine' or 'thiamin', also known as '
vitamin B
1', is one of the
B vitamins. It is a colorless
compound with
chemical formula C12H17N4OS. It is
soluble in
water and insoluble in
alcohol. Thiamine decomposes if heated. Its chemical structure contains a
pyrimidine ring and a
thiazole ring.
History
Thiamine was first discovered in 1910 by
Umetaro Suzuki in
Japan when researching how
rice bran cured patients of
beriberi. He named it 'aberic acid'. He did not determine its chemical composition, nor that it was an
amine.
It was first crystallized by Jansen and Donath in 1926 (they named it aneurin, for antineuritic vitamin).
Its chemical composition and synthesis was finally reported by
Robert R. Williams in 1935. He also coined the name for it, thiamine.
Thiamine phosphate derivatives
There are four known natural thiamine phosphate derivatives:
thiamine monophosphate (ThMP),
thiamine diphosphate (ThDP),
thiamine triphosphate (ThTP) and the recently discovered
adenosine thiamine triphosphate (AThTP).
Thiamine pyrophosphate
Thiamine pyrophosphate (TPP), also known as ''thiamine diphosphate'' (ThDP), is a
coenzyme for several enzymes that catalyze the
dehydrogenation (
decarboxylation and subsequent conjugation to
Coenzyme A) of alpha-keto acids. Examples include:
★ In
mammals:
★
★
pyruvate dehydrogenase and
α-ketoglutarate dehydrogenase (
metabolism of
carbohydrates)
★
★
branched-chain alpha-keto acid dehydrogenase
★
★
2-hydroxyphytanoyl-CoA lyase
★
★
transketolase (functions in the
pentose phosphate pathway to synthesize
NADPH and the pentose
sugars
deoxyribose and
ribose )
★ In other species:
★
★
pyruvate decarboxylase (in
yeast)
★
★ several additional
bacterial enzymes
TPP is synthesized by the enzyme
thiamine pyrophosphokinase, which requires free thiamine,
magnesium, and
adenosine triphosphate.
Thiamine triphosphate
''
Thiamine triphosphate'' (ThTP) was long considered a specific neuroactive form of thiamine.
However, recently it was shown that ThTP exists in
bacteria,
fungi,
plants and
animals suggesting a much more general cellular role. In particular in
E. coli it seems to play a role in response to amino acid starvation.
Adenosine thiamine triphosphate
''
Adenosine thiamine triphosphate'' (AThTP) or thiaminylated adenosine triphosphate has recently been discovered in ''
Escherichia coli'' where it accumulates as a result of carbon starvation. In ''E. coli'', AThTP may account for up to 20 % of total thiamine.
It also exists in lesser amounts in
yeast, roots of higher plants and animal tissues.
Nutrition
Thiamine plays an important role in helping the body metabolize carbohydrates and fat to produce energy. It is essential for normal growth and development and helps to maintain proper functioning of the heart and the nervous and digestive systems. Thiamine is water-soluble and cannot be stored in the body; however, once absorbed, the vitamin is concentrated in muscle tissue.
Good sources
Thiamine is found naturally in the following foods, each of which contains at least 0.1 mg of the vitamin per 28-100 g (1-3.5 oz):
Green peas,
Spinach,
Liver,
Beef,
Pork,
Navy beans,
Nuts,
Pinto beans,
Bananas,
Soybeans,
Goji berries,
Whole-grain and
Enriched Cereals,
Breads,
Yeast,the
aleurone layer of unpolished
rice, and
Legumes.
Deficiency
Systemic thiamine deficiency can lead to myriad problems including
neurodegeneration, wasting and death. A lack of thiamine can be caused by
malnutrition,
alcoholism, a diet high in
thiaminase-rich foods (raw freshwater fish, raw
shellfish,
ferns) and/or foods high in anti-thiamine factors (
tea,
coffee,
betel nuts)
[1].
Well-known syndromes caused by thiamine deficiency include
Wernicke-Korsakoff syndrome and
beriberi, diseases also common with chronic alcoholism.
It is thought that many people with
diabetes have a deficiency of thiamine
[1] and that this may be linked to some of the complications that can occur.
Diagnostic testing for B1 deficiency
A positive diagnosis test for Thiamine deficiency can be ascertained by measuring the activity of
transketolase in
erythrocyte . Thiamine can also be skeeted directly in whole blood following the conversion of thiamine to a
fluorescent thiochrome derivative.
August 10, 2007 article states deficiency of Vitamin B1 not revealed by above tests. See http://www2.warwick.ac.uk/newsandevents/pressreleases/researchers_find_vitamin/ for complete information regarding diabetic neuropathy and Vitamin B1 Deficiency.
Genetic diseases
Genetic diseases of thiamine transport are rare but serious. Thiamine Responsive Megaloblastic Anemia with diabetes mellitus and sensorineural deafness (TRMA)
[Thiamine Responsive Megaloblastic Anemia with severe diabetes mellitus and sensorineural deafness (TRMA) PMID 249270] is an autosomal recessive disorder caused by mutations in the gene
SLC19A2,
[SLC19A2 PMID 603941] a high affinity thiamine transporter. TRMA patients do not show signs of systemic thiamine deficiency, suggesting redundancy in the thiamine transport system. This has led to the discovery of a second high affinity thiamine transporter,
SLC19A3.
[SLC19A3 PMID 606152]
Research
High doses
The
RDA in most countries is set at about 1.4 mg. However, tests on volunteers at daily doses of about 50 mg have claimed an increase in mental acuity. ''
[2]
Thiamine as an insect repellent
Some studies suggest that taking thiamine (vitamin B1) 25 mg to 50 mg three times per day is effective in reducing mosquito bites. A large intake of Thiamine produces a skin odor that is not detectable by humans, but is disagreeable to female mosquitoes.
[3] Thiamine takes more than 2 weeks before the odor fully saturates the skin. With the advances in topical preparations there is an increasing number of Thiamine based repellent products. Whilst there is considerable anecdotal evidence of Thiamine products being effective in the field (Australia, US and Canada), there has yet to be any clinical trials run to demonstrate the efficacy of these products.
Autism
A 2006 pilot study administered thiamine tetrahydrofurfuryl disulfide (TTFD) rectally to ten
autism spectrum children, and found beneficial clinical effect in eight.
[4] This study has not been replicated and a 2006 review of thiamine by the same author did not mention thiamine's possible effect on
autism.
[5]
References
1. "Thiamin", Jane Higdon, Micronutrient Information Center, Linus Pauling Institute
2. Thiamine's Mood-Mending Qualities, Richard N. Podel, Nutrition Science News, January 1999.
3. Pediatric Clinics of North America, 16:191, 1969
4. Treatment of autism spectrum children with thiamine tetrahydrofurfuryl disulfide: a pilot study, Lonsdale D, Shamberger RJ, Audhya T, , , Neuro Endocrinol. Lett., 2002
5. A review of the biochemistry, metabolism and clinical benefits of thiamin(e) and its derivatives, Lonsdale D, , , Evid Based Complement Alternat Med,
External links
★
"Branched-Chain Amino Acid Metabolism" at ncbi.nlm.nih.gov
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