Malaysia Swiflets nests contain 20 to 30 % of carbohydrate. What is carbohydrate and its benefits to mankind?
[Expand] Support Wikipedia: a non-profit project. Donate Now » [Expand] Support Wikipedia: a non-profit project. — Donate Now
Carbohydrate
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Lactose is a disaccharide found in milk. It is composed of a molecule of D-galactose and a molecule of D-glucose bonded by a β-1-4 glycosidic linkage.Carbohydrates (from 'hydrates of carbon') or saccharides (Greek σάκχαρον, sákcharon, meaning "sugar") are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy (starch, glycogen) and structural components (cellulose in plants, chitin in animals). Additionally, carbohydrates and their derivatives play major roles in the working process of the immune system, fertilization, pathogenesis, blood clotting, and development.[1]
Chemically, carbohydrates are simple organic compounds that are aldehydes or ketones with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. The basic carbohydrate units are called monosaccharides, such as glucose, galactose, and fructose. The general stoichiometric formula of an unmodified monosaccharide is (C·H2O)n, where n is any number of three or greater; however, the use of this word does not follow this exact definition and many molecules with formulae that differ slightly from this are still called carbohydrates, and others that possess formulae agreeing with this general rule are not called carbohydrates (eg formaldehyde).[2]
Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in almost limitless ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetylglucosamine, a nitrogen-containing form of glucose. The names of carbohydrates often end in the suffix -ose.
Contents [hide]
1 Monosaccharides
1.1 Classification of monosaccharides
1.2 Conformation
1.3 Use in living organisms
2 Disaccharides
3 Oligosaccharides and polysaccharides
4 Nutrition
4.1 Classification
5 Metabolism
5.1 Catabolism
6 Carbohydrate chemistry
7 See also
8 References
9 External links
Monosaccharides
Main article: Monosaccharide
D-glucose is an aldohexose with the formula (C·H2O)6. The red atoms highlight the aldehyde group, and the blue atoms highlight the asymmetric center furthest from the aldehyde; because this -OH is on the right of the Fischer projection, this is a D sugar.Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates. The general chemical formula of an unmodified monosaccharide is (C•H2O)n, where n is any number of three or greater.
Classification of monosaccharides
The α and β anomers of glucose. Note the position of the anomeric carbon (red or green) relative to the CH2OH group bound to carbon 5: they are either on the opposite sides (α), or the same side (β).
Monosaccharides are classified according to three different characteristics: the placement of its carbonyl group, the number of carbon atoms it contains, and its chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. [3] These two systems of classification are often combined. For example, glucose is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone).
Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons, are asymmetric, making them stereocenters with two possible configurations each (R or S). Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula. The aldohexose D-glucose, for example, has the formula (C·H2O)6, of which all but two of its six carbons atoms are stereogenic, making D-glucose one of 24 = 16 possible stereoisomers. In the case of glyceraldehyde, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. 1,3-dihydroxyacetone, the ketose corresponding to the aldose glyceraldehyde, is a symmetric molecule with no stereocenters). The assignment of D or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group: in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar. Because D sugars are biologically far more common, the D is often omitted
Conformation
Glucose can exist in both a straight-chain and ring form.The aldehyde or ketone group of a straight-chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, forming a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight-chain form.
During the conversion from straight-chain form to cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a chiral center with two possible configurations: the oxygen atom may take a position either above or below the plane of the ring. The resulting possible pair of stereoisomers are called anomers. In the α anomer, the -OH substituent on the anomeric carbon rests on the opposite side (trans) of the ring from the CH2OH side branch. The alternative form, in which the CH2OH substituent and the anomeric hydroxyl are on the same side (cis) of the plane of the ring, is called the β anomer. You can remember that the β anomer is cis by the mnemonic, "It's always better to βe up". Because the ring and straight-chain forms readily interconvert, both anomers exist in equilibrium.
Use in living organisms
Monosaccharides are the major source of fuel for metabolism, being used both as an energy source (glucose being the most important in nature) and in biosynthesis. When monosaccharides are not immediately needed by many cells they are often converted to more space efficient forms, often polysaccharides. In many animals, including humans, this storage form is glycogen, especially in liver and muscle cells. In plants, starch is used for the same purpose.
Disaccharides
Sucrose, also known as table sugar, is a common disaccharide. It is composed of two monosaccharides: D-glucose (left) and D-fructose (right).Main article: Disaccharide
Two joined monosaccharides are called a disaccharides and these are the simplest polysaccharides. Examples include sucrose and lactose. They are composed of two monosaccharide units bound together by a covalent bond known as a glycosidic linkage formed via a dehydration reaction, resulting in the loss of a hydrogen atom from one monosaccharide and a hydroxyl group from the other. The formula of unmodified disaccharides is C12H22O11. Although there are numerous kinds of disaccharides, a handful of disaccharides are particularly notable.
Sucrose, pictured to the right, is the most abundant disaccharide, and the main form in which carbohydrates are transported in plants. It is composed of one D-glucose molecule and one D-fructose molecule. The systematic name for sucrose, O-α-D-glucopyranosyl-(1→2)-D-fructofuranoside, indicates four things:
Its monosaccharides: glucose and fructose
Their ring types: glucose is a pyranose, and fructose is a furanose
How they are linked together: the oxygen on carbon number 1 (C1) of α-D-glucose is linked to the C2 of D-fructose.
The -oside suffix indicates that the anomeric carbon of both monosaccharides participates in the glycosidic bond.
Lactose, a disaccharide composed of one D-galactose molecule and one D-glucose molecule, occurs naturally in mammalian milk. The systematic name for lactose is O-β-D-galactopyranosyl-(1→4)-D-glucopyranose. Other notable disaccharides include maltose (two D-glucoses linked α-1,4) and cellulobiose (two D-glucoses linked β-1,4).
Oligosaccharides and polysaccharides
Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, the other being amylopectin.Main articles: Oligosaccharide and Polysaccharide
Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between two and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary according to personal opinion. Examples of oligosaccharides include the disaccharides mentioned above, the trisaccharide raffinose and the tetrasaccharide stachyose.
Oligosaccharides are found as a common form of protein posttranslational modification. Such posttranslational modifications include the Lewis and ABO oligosaccharides responsible for blood group classifications and so of tissue incompatibilities, the alpha-Gal epitope responsible for hyperacute rejection in xenotransplanation, and O-GlcNAc modifications.
Polysaccharides represent an important class of biological polymers. Their function in living organisms is usually either structure or storage related. Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called 'animal starch'. Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms, and is claimed to be the most abundant organic molecule on earth.[4] It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin's structure has a similar structure, but has nitrogen containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has multiple uses, including surgical threads.
Other polysaccharides include callose or laminarin, xylan, mannan, fucoidan, and galactomannan.
Nutrition
Grain products: rich sources of complex and simple carbohydratesCarbohydrates require less water to digest than proteins or fats and are the most common source of energy in living things. Proteins and fat are necessary building components for body tissue and cells and are also a source of energy for most organisms.
Carbohydrates are not essential nutrients in humans: the body can obtain all its energy from protein and fats[5][6]. However, the brain and neurons generally cannot burn fat and need glucose for energy; the body can make some glucose from a few of the amino acids in protein and also from the glycerol backbone in triglycerides. Carbohydrate contains 3.75 and proteins 4 kilocalories per gram, respectively, while fats contain 9 kilocalories per gram. In the case of protein, this is somewhat misleading as only some amino acids are usable for fuel. Likewise, in humans, only some carbohydrates are usable for fuel; many monosaccharides and some disaccharides. Other carbohydrate types can be used, but only with the assistance of gut bacteria. Ruminants and termites, can even process cellulose, which is indigestible to other organisms.
Foods high in carbohydrates include breads, pastas, beans, potatoes, bran, rice and cereals. Most such foods are high in starch.
Based on the effects on risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 40-65% of dietary energy from carbohydrates.[7] The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55-75% of total energy from carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates).[8]
Classification
Dietitians and other certified food scientists commonly classify carbohydrates as simple (monosaccharides and disaccharides) or complex (oligosaccharides and polysaccharides). The term complex carbohydrate was first used in the Senate Select Committee publication Dietary Goals for the United States (1977), where it denoted "fruit, vegetables and whole-grains".[9] Dietary guidelines generally recommend that complex carbohydrates, and such nutrient-rich simple carbohydrate sources such as fruit (glucose or fructose) and dairy products (lactose) make up the bulk of carbohydrate consumption. This excludes such sources of simple sugars as candy and sugary drinks. The USDA's Dietary Guidelines for Americans 2005 dispensed with the simple/complex distinction, instead recommending fiber-rich foods and whole grains.[10]
The glycemic index and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate-rich foods based on the rapidity of their effect on blood glucose levels. The insulin index is a similar, more recent classification method which ranks foods based on their effects on blood insulin levels, which are caused by glucose (or starch) and some amino acids in food. Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods.
Metabolism
Main article: Carbohydrate metabolism
Please help improve this section by expanding it. Further information might be found on the talk page. (June 2008)
This section repeats, in whole or part, the text of other article(s) or section(s).
Please discuss this issue on the talk page and conform with Wikipedia's Manual of Style by replacing the section with a link and a summary of the repeated text, or by spinning off the repeated text into an article in its own right.
Catabolism
Catabolism is the metabolic reaction cells undergo in order to extract energy. There are two major metabolic pathways of monosaccharide catabolism:
Glycolysis
Citric acid cycle
Oligo/polysaccharides are cleaved first to smaller monosaccharides by enzymes called Glycoside hydrolases. The monosaccharide units can then enter into monosaccharide catabolism. In some cases, as with humans, not all carbohydrate types are usable as the digestive and metabolic enzymes necessary are not present. For instance, neither horses nor humans nor cats can digest and use cellulose, but ruminants and termites can.
Carbohydrate chemistry
Carbohydrates are reactants in many organic reactions. For example:
Carbohydrate acetalisation
Cyanohydrin reaction
Lobry-de Bruyn-van Ekenstein transformation
Amadori rearrangement
Nef reaction
Wohl degradation
Koenigs-Knorr reaction
See also
Wikimedia Commons has media related to: Carbohydrates
Biochemistry
Bioplastic
Gluconeogenesis
Glycolipid
Glycoprotein
Low-carbohydrate diet
No-carbohydrate diet
Macromolecules
Nutrition
Pentose phosphate pathway
Photosynthesis
Sugar
[show]v • d • eMetabolism
Catabolism - Anabolism
Metabolic pathway - Metabolic network - Cellular respiration (Anaerobic/Aerobic)
Protein metabolism - Carbohydrate metabolism - Lipid metabolism - Iron metabolism
[show]v • d • eFood chemistry
Additives · Carbohydrates · Coloring · Enzymes · Essential fatty acids · Flavors · Lipids · Minerals · Proteins · Vitamins · Water
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
References
^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59. ISBN 0-13-981176-1.
^ Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings. ISBN 0-8053-3066-6
^ Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall. ISBN 0-13-250882-6. http://www.phschool.com/el_marketing.html.
^ N.A.Campbell (1996) Biology (4th edition). Benjamin Cummings NY. p.23 ISBN 0-8053-1957-3
^ Is dietary carbohydrate essential for human nutrition? - Westman 75 (5): 951 - American Journal of Clinical Nutrition
^ A High-Protein, High-Fat, Carbohydrate-Free Diet Reduces Energy Intake, Hepatic Lipogenesis, and Adiposity in Rats - Pichon et al. 136 (5): 1256 - Journal of Nutrition
^ Food and Nutrition Board (2002/2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press. Page 769. ISBN 0-309-08537-3
^ Joint WHO/FAO expert consultation (2003). Diet, Nutrition and the Prevention of Chronic Diseases (PDF). Geneva: World Health Organization. Pages 55-56. ISBN 92-4-120916-X
^ Joint WHO/FAO expert consultation (1998), Carbohydrates in human nutrition, chapter 1. ISBN 92-5-104114-8.
^ DHHS and USDA, Dietary Guidelines for Americans 2005, Chapter 7 Carbohydrates
External links
Carbohydrates, including interactive models and animations (Requires MDL Chime)
IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN): Carbohydrate Nomenclature
Carbohydrates detailed
Carbohydrates and Glycosylation - The Virtual Library of Biochemistry and Cell Biology
Consortium for Functional Glycomics
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
Retrieved from "http://en.wikipedia.org/wiki/Carbohydrate"
Categories: Duplicate Articles | Carbohydrates | Nutrition
Hidden categories: Semi-protected against vandalism | Articles to be expanded since June 2008 | All articles to be expanded
ViewsArticle Discussion View source History Personal toolsLog in / create account Navigation
Tuesday, December 9, 2008
Friday, December 5, 2008
Do you know what is swiflet nests and its benefits to mankind?
[Expand] Support Wikipedia: a non-profit project. Donate Now » [Expand] Support Wikipedia: a non-profit project. — Donate Now
Carbohydrate
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Lactose is a disaccharide found in milk. It is composed of a molecule of D-galactose and a molecule of D-glucose bonded by a β-1-4 glycosidic linkage.Carbohydrates (from 'hydrates of carbon') or saccharides (Greek σάκχαρον, sákcharon, meaning "sugar") are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy (starch, glycogen) and structural components (cellulose in plants, chitin in animals). Additionally, carbohydrates and their derivatives play major roles in the working process of the immune system, fertilization, pathogenesis, blood clotting, and development.[1]
Chemically, carbohydrates are simple organic compounds that are aldehydes or ketones with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. The basic carbohydrate units are called monosaccharides, such as glucose, galactose, and fructose. The general stoichiometric formula of an unmodified monosaccharide is (C·H2O)n, where n is any number of three or greater; however, the use of this word does not follow this exact definition and many molecules with formulae that differ slightly from this are still called carbohydrates, and others that possess formulae agreeing with this general rule are not called carbohydrates (eg formaldehyde).[2]
Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in almost limitless ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetylglucosamine, a nitrogen-containing form of glucose. The names of carbohydrates often end in the suffix -ose.
Contents [hide]
1 Monosaccharides
1.1 Classification of monosaccharides
1.2 Conformation
1.3 Use in living organisms
2 Disaccharides
3 Oligosaccharides and polysaccharides
4 Nutrition
4.1 Classification
5 Metabolism
5.1 Catabolism
6 Carbohydrate chemistry
7 See also
8 References
9 External links
Monosaccharides
Main article: Monosaccharide
D-glucose is an aldohexose with the formula (C·H2O)6. The red atoms highlight the aldehyde group, and the blue atoms highlight the asymmetric center furthest from the aldehyde; because this -OH is on the right of the Fischer projection, this is a D sugar.Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates. The general chemical formula of an unmodified monosaccharide is (C•H2O)n, where n is any number of three or greater.
Classification of monosaccharides
The α and β anomers of glucose. Note the position of the anomeric carbon (red or green) relative to the CH2OH group bound to carbon 5: they are either on the opposite sides (α), or the same side (β).
Monosaccharides are classified according to three different characteristics: the placement of its carbonyl group, the number of carbon atoms it contains, and its chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. [3] These two systems of classification are often combined. For example, glucose is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone).
Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons, are asymmetric, making them stereocenters with two possible configurations each (R or S). Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula. The aldohexose D-glucose, for example, has the formula (C·H2O)6, of which all but two of its six carbons atoms are stereogenic, making D-glucose one of 24 = 16 possible stereoisomers. In the case of glyceraldehyde, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. 1,3-dihydroxyacetone, the ketose corresponding to the aldose glyceraldehyde, is a symmetric molecule with no stereocenters). The assignment of D or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group: in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar. Because D sugars are biologically far more common, the D is often omitted
Conformation
Glucose can exist in both a straight-chain and ring form.The aldehyde or ketone group of a straight-chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, forming a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight-chain form.
During the conversion from straight-chain form to cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a chiral center with two possible configurations: the oxygen atom may take a position either above or below the plane of the ring. The resulting possible pair of stereoisomers are called anomers. In the α anomer, the -OH substituent on the anomeric carbon rests on the opposite side (trans) of the ring from the CH2OH side branch. The alternative form, in which the CH2OH substituent and the anomeric hydroxyl are on the same side (cis) of the plane of the ring, is called the β anomer. You can remember that the β anomer is cis by the mnemonic, "It's always better to βe up". Because the ring and straight-chain forms readily interconvert, both anomers exist in equilibrium.
Use in living organisms
Monosaccharides are the major source of fuel for metabolism, being used both as an energy source (glucose being the most important in nature) and in biosynthesis. When monosaccharides are not immediately needed by many cells they are often converted to more space efficient forms, often polysaccharides. In many animals, including humans, this storage form is glycogen, especially in liver and muscle cells. In plants, starch is used for the same purpose.
Disaccharides
Sucrose, also known as table sugar, is a common disaccharide. It is composed of two monosaccharides: D-glucose (left) and D-fructose (right).Main article: Disaccharide
Two joined monosaccharides are called a disaccharides and these are the simplest polysaccharides. Examples include sucrose and lactose. They are composed of two monosaccharide units bound together by a covalent bond known as a glycosidic linkage formed via a dehydration reaction, resulting in the loss of a hydrogen atom from one monosaccharide and a hydroxyl group from the other. The formula of unmodified disaccharides is C12H22O11. Although there are numerous kinds of disaccharides, a handful of disaccharides are particularly notable.
Sucrose, pictured to the right, is the most abundant disaccharide, and the main form in which carbohydrates are transported in plants. It is composed of one D-glucose molecule and one D-fructose molecule. The systematic name for sucrose, O-α-D-glucopyranosyl-(1→2)-D-fructofuranoside, indicates four things:
Its monosaccharides: glucose and fructose
Their ring types: glucose is a pyranose, and fructose is a furanose
How they are linked together: the oxygen on carbon number 1 (C1) of α-D-glucose is linked to the C2 of D-fructose.
The -oside suffix indicates that the anomeric carbon of both monosaccharides participates in the glycosidic bond.
Lactose, a disaccharide composed of one D-galactose molecule and one D-glucose molecule, occurs naturally in mammalian milk. The systematic name for lactose is O-β-D-galactopyranosyl-(1→4)-D-glucopyranose. Other notable disaccharides include maltose (two D-glucoses linked α-1,4) and cellulobiose (two D-glucoses linked β-1,4).
Oligosaccharides and polysaccharides
Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, the other being amylopectin.Main articles: Oligosaccharide and Polysaccharide
Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between two and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary according to personal opinion. Examples of oligosaccharides include the disaccharides mentioned above, the trisaccharide raffinose and the tetrasaccharide stachyose.
Oligosaccharides are found as a common form of protein posttranslational modification. Such posttranslational modifications include the Lewis and ABO oligosaccharides responsible for blood group classifications and so of tissue incompatibilities, the alpha-Gal epitope responsible for hyperacute rejection in xenotransplanation, and O-GlcNAc modifications.
Polysaccharides represent an important class of biological polymers. Their function in living organisms is usually either structure or storage related. Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called 'animal starch'. Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms, and is claimed to be the most abundant organic molecule on earth.[4] It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin's structure has a similar structure, but has nitrogen containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has multiple uses, including surgical threads.
Other polysaccharides include callose or laminarin, xylan, mannan, fucoidan, and galactomannan.
Nutrition
Grain products: rich sources of complex and simple carbohydratesCarbohydrates require less water to digest than proteins or fats and are the most common source of energy in living things. Proteins and fat are necessary building components for body tissue and cells and are also a source of energy for most organisms.
Carbohydrates are not essential nutrients in humans: the body can obtain all its energy from protein and fats[5][6]. However, the brain and neurons generally cannot burn fat and need glucose for energy; the body can make some glucose from a few of the amino acids in protein and also from the glycerol backbone in triglycerides. Carbohydrate contains 3.75 and proteins 4 kilocalories per gram, respectively, while fats contain 9 kilocalories per gram. In the case of protein, this is somewhat misleading as only some amino acids are usable for fuel. Likewise, in humans, only some carbohydrates are usable for fuel; many monosaccharides and some disaccharides. Other carbohydrate types can be used, but only with the assistance of gut bacteria. Ruminants and termites, can even process cellulose, which is indigestible to other organisms.
Foods high in carbohydrates include breads, pastas, beans, potatoes, bran, rice and cereals. Most such foods are high in starch.
Based on the effects on risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 40-65% of dietary energy from carbohydrates.[7] The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55-75% of total energy from carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates).[8]
Classification
Dietitians and other certified food scientists commonly classify carbohydrates as simple (monosaccharides and disaccharides) or complex (oligosaccharides and polysaccharides). The term complex carbohydrate was first used in the Senate Select Committee publication Dietary Goals for the United States (1977), where it denoted "fruit, vegetables and whole-grains".[9] Dietary guidelines generally recommend that complex carbohydrates, and such nutrient-rich simple carbohydrate sources such as fruit (glucose or fructose) and dairy products (lactose) make up the bulk of carbohydrate consumption. This excludes such sources of simple sugars as candy and sugary drinks. The USDA's Dietary Guidelines for Americans 2005 dispensed with the simple/complex distinction, instead recommending fiber-rich foods and whole grains.[10]
The glycemic index and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate-rich foods based on the rapidity of their effect on blood glucose levels. The insulin index is a similar, more recent classification method which ranks foods based on their effects on blood insulin levels, which are caused by glucose (or starch) and some amino acids in food. Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods.
Metabolism
Main article: Carbohydrate metabolism
Please help improve this section by expanding it. Further information might be found on the talk page. (June 2008)
This section repeats, in whole or part, the text of other article(s) or section(s).
Please discuss this issue on the talk page and conform with Wikipedia's Manual of Style by replacing the section with a link and a summary of the repeated text, or by spinning off the repeated text into an article in its own right.
Catabolism
Catabolism is the metabolic reaction cells undergo in order to extract energy. There are two major metabolic pathways of monosaccharide catabolism:
Glycolysis
Citric acid cycle
Oligo/polysaccharides are cleaved first to smaller monosaccharides by enzymes called Glycoside hydrolases. The monosaccharide units can then enter into monosaccharide catabolism. In some cases, as with humans, not all carbohydrate types are usable as the digestive and metabolic enzymes necessary are not present. For instance, neither horses nor humans nor cats can digest and use cellulose, but ruminants and termites can.
Carbohydrate chemistry
Carbohydrates are reactants in many organic reactions. For example:
Carbohydrate acetalisation
Cyanohydrin reaction
Lobry-de Bruyn-van Ekenstein transformation
Amadori rearrangement
Nef reaction
Wohl degradation
Koenigs-Knorr reaction
See also
Wikimedia Commons has media related to: Carbohydrates
Biochemistry
Bioplastic
Gluconeogenesis
Glycolipid
Glycoprotein
Low-carbohydrate diet
No-carbohydrate diet
Macromolecules
Nutrition
Pentose phosphate pathway
Photosynthesis
Sugar
[show]v • d • eMetabolism
Catabolism - Anabolism
Metabolic pathway - Metabolic network - Cellular respiration (Anaerobic/Aerobic)
Protein metabolism - Carbohydrate metabolism - Lipid metabolism - Iron metabolism
[show]v • d • eFood chemistry
Additives · Carbohydrates · Coloring · Enzymes · Essential fatty acids · Flavors · Lipids · Minerals · Proteins · Vitamins · Water
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
References
^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59. ISBN 0-13-981176-1.
^ Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings. ISBN 0-8053-3066-6
^ Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall. ISBN 0-13-250882-6. http://www.phschool.com/el_marketing.html.
^ N.A.Campbell (1996) Biology (4th edition). Benjamin Cummings NY. p.23 ISBN 0-8053-1957-3
^ Is dietary carbohydrate essential for human nutrition? - Westman 75 (5): 951 - American Journal of Clinical Nutrition
^ A High-Protein, High-Fat, Carbohydrate-Free Diet Reduces Energy Intake, Hepatic Lipogenesis, and Adiposity in Rats - Pichon et al. 136 (5): 1256 - Journal of Nutrition
^ Food and Nutrition Board (2002/2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press. Page 769. ISBN 0-309-08537-3
^ Joint WHO/FAO expert consultation (2003). Diet, Nutrition and the Prevention of Chronic Diseases (PDF). Geneva: World Health Organization. Pages 55-56. ISBN 92-4-120916-X
^ Joint WHO/FAO expert consultation (1998), Carbohydrates in human nutrition, chapter 1. ISBN 92-5-104114-8.
^ DHHS and USDA, Dietary Guidelines for Americans 2005, Chapter 7 Carbohydrates
External links
Carbohydrates, including interactive models and animations (Requires MDL Chime)
IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN): Carbohydrate Nomenclature
Carbohydrates detailed
Carbohydrates and Glycosylation - The Virtual Library of Biochemistry and Cell Biology
Consortium for Functional Glycomics
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
Retrieved from "http://en.wikipedia.org/wiki/Carbohydrate"
Categories: Duplicate Articles | Carbohydrates | Nutrition
Hidden categories: Semi-protected against vandalism | Articles to be expanded since June 2008 | All articles to be expanded
ViewsArticle Discussion View source History Personal toolsLog in / create account Navigation
[Expand] Support Wikipedia: a non-profit project. Donate Now » [Expand] Support Wikipedia: a non-profit project. — Donate Now
Carbohydrate
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Lactose is a disaccharide found in milk. It is composed of a molecule of D-galactose and a molecule of D-glucose bonded by a β-1-4 glycosidic linkage.Carbohydrates (from 'hydrates of carbon') or saccharides (Greek σάκχαρον, sákcharon, meaning "sugar") are the most abundant of the four major classes of biomolecules. They fill numerous roles in living things, such as the storage and transport of energy (starch, glycogen) and structural components (cellulose in plants, chitin in animals). Additionally, carbohydrates and their derivatives play major roles in the working process of the immune system, fertilization, pathogenesis, blood clotting, and development.[1]
Chemically, carbohydrates are simple organic compounds that are aldehydes or ketones with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group. The basic carbohydrate units are called monosaccharides, such as glucose, galactose, and fructose. The general stoichiometric formula of an unmodified monosaccharide is (C·H2O)n, where n is any number of three or greater; however, the use of this word does not follow this exact definition and many molecules with formulae that differ slightly from this are still called carbohydrates, and others that possess formulae agreeing with this general rule are not called carbohydrates (eg formaldehyde).[2]
Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in almost limitless ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is a modified version of ribose; chitin is composed of repeating units of N-acetylglucosamine, a nitrogen-containing form of glucose. The names of carbohydrates often end in the suffix -ose.
Contents [hide]
1 Monosaccharides
1.1 Classification of monosaccharides
1.2 Conformation
1.3 Use in living organisms
2 Disaccharides
3 Oligosaccharides and polysaccharides
4 Nutrition
4.1 Classification
5 Metabolism
5.1 Catabolism
6 Carbohydrate chemistry
7 See also
8 References
9 External links
Monosaccharides
Main article: Monosaccharide
D-glucose is an aldohexose with the formula (C·H2O)6. The red atoms highlight the aldehyde group, and the blue atoms highlight the asymmetric center furthest from the aldehyde; because this -OH is on the right of the Fischer projection, this is a D sugar.Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates. The general chemical formula of an unmodified monosaccharide is (C•H2O)n, where n is any number of three or greater.
Classification of monosaccharides
The α and β anomers of glucose. Note the position of the anomeric carbon (red or green) relative to the CH2OH group bound to carbon 5: they are either on the opposite sides (α), or the same side (β).
Monosaccharides are classified according to three different characteristics: the placement of its carbonyl group, the number of carbon atoms it contains, and its chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. [3] These two systems of classification are often combined. For example, glucose is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone).
Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons, are asymmetric, making them stereocenters with two possible configurations each (R or S). Because of this asymmetry, a number of isomers may exist for any given monosaccharide formula. The aldohexose D-glucose, for example, has the formula (C·H2O)6, of which all but two of its six carbons atoms are stereogenic, making D-glucose one of 24 = 16 possible stereoisomers. In the case of glyceraldehyde, an aldotriose, there is one pair of possible stereoisomers, which are enantiomers and epimers. 1,3-dihydroxyacetone, the ketose corresponding to the aldose glyceraldehyde, is a symmetric molecule with no stereocenters). The assignment of D or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group: in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar. Because D sugars are biologically far more common, the D is often omitted
Conformation
Glucose can exist in both a straight-chain and ring form.The aldehyde or ketone group of a straight-chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, forming a heterocyclic ring with an oxygen bridge between two carbon atoms. Rings with five and six atoms are called furanose and pyranose forms, respectively, and exist in equilibrium with the straight-chain form.
During the conversion from straight-chain form to cyclic form, the carbon atom containing the carbonyl oxygen, called the anomeric carbon, becomes a chiral center with two possible configurations: the oxygen atom may take a position either above or below the plane of the ring. The resulting possible pair of stereoisomers are called anomers. In the α anomer, the -OH substituent on the anomeric carbon rests on the opposite side (trans) of the ring from the CH2OH side branch. The alternative form, in which the CH2OH substituent and the anomeric hydroxyl are on the same side (cis) of the plane of the ring, is called the β anomer. You can remember that the β anomer is cis by the mnemonic, "It's always better to βe up". Because the ring and straight-chain forms readily interconvert, both anomers exist in equilibrium.
Use in living organisms
Monosaccharides are the major source of fuel for metabolism, being used both as an energy source (glucose being the most important in nature) and in biosynthesis. When monosaccharides are not immediately needed by many cells they are often converted to more space efficient forms, often polysaccharides. In many animals, including humans, this storage form is glycogen, especially in liver and muscle cells. In plants, starch is used for the same purpose.
Disaccharides
Sucrose, also known as table sugar, is a common disaccharide. It is composed of two monosaccharides: D-glucose (left) and D-fructose (right).Main article: Disaccharide
Two joined monosaccharides are called a disaccharides and these are the simplest polysaccharides. Examples include sucrose and lactose. They are composed of two monosaccharide units bound together by a covalent bond known as a glycosidic linkage formed via a dehydration reaction, resulting in the loss of a hydrogen atom from one monosaccharide and a hydroxyl group from the other. The formula of unmodified disaccharides is C12H22O11. Although there are numerous kinds of disaccharides, a handful of disaccharides are particularly notable.
Sucrose, pictured to the right, is the most abundant disaccharide, and the main form in which carbohydrates are transported in plants. It is composed of one D-glucose molecule and one D-fructose molecule. The systematic name for sucrose, O-α-D-glucopyranosyl-(1→2)-D-fructofuranoside, indicates four things:
Its monosaccharides: glucose and fructose
Their ring types: glucose is a pyranose, and fructose is a furanose
How they are linked together: the oxygen on carbon number 1 (C1) of α-D-glucose is linked to the C2 of D-fructose.
The -oside suffix indicates that the anomeric carbon of both monosaccharides participates in the glycosidic bond.
Lactose, a disaccharide composed of one D-galactose molecule and one D-glucose molecule, occurs naturally in mammalian milk. The systematic name for lactose is O-β-D-galactopyranosyl-(1→4)-D-glucopyranose. Other notable disaccharides include maltose (two D-glucoses linked α-1,4) and cellulobiose (two D-glucoses linked β-1,4).
Oligosaccharides and polysaccharides
Amylose is a linear polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, the other being amylopectin.Main articles: Oligosaccharide and Polysaccharide
Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between two and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary according to personal opinion. Examples of oligosaccharides include the disaccharides mentioned above, the trisaccharide raffinose and the tetrasaccharide stachyose.
Oligosaccharides are found as a common form of protein posttranslational modification. Such posttranslational modifications include the Lewis and ABO oligosaccharides responsible for blood group classifications and so of tissue incompatibilities, the alpha-Gal epitope responsible for hyperacute rejection in xenotransplanation, and O-GlcNAc modifications.
Polysaccharides represent an important class of biological polymers. Their function in living organisms is usually either structure or storage related. Starch (a polymer of glucose) is used as a storage polysaccharide in plants, being found in the form of both amylose and the branched amylopectin. In animals, the structurally similar glucose polymer is the more densely branched glycogen, sometimes called 'animal starch'. Glycogen's properties allow it to be metabolized more quickly, which suits the active lives of moving animals.
Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms, and is claimed to be the most abundant organic molecule on earth.[4] It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin's structure has a similar structure, but has nitrogen containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has multiple uses, including surgical threads.
Other polysaccharides include callose or laminarin, xylan, mannan, fucoidan, and galactomannan.
Nutrition
Grain products: rich sources of complex and simple carbohydratesCarbohydrates require less water to digest than proteins or fats and are the most common source of energy in living things. Proteins and fat are necessary building components for body tissue and cells and are also a source of energy for most organisms.
Carbohydrates are not essential nutrients in humans: the body can obtain all its energy from protein and fats[5][6]. However, the brain and neurons generally cannot burn fat and need glucose for energy; the body can make some glucose from a few of the amino acids in protein and also from the glycerol backbone in triglycerides. Carbohydrate contains 3.75 and proteins 4 kilocalories per gram, respectively, while fats contain 9 kilocalories per gram. In the case of protein, this is somewhat misleading as only some amino acids are usable for fuel. Likewise, in humans, only some carbohydrates are usable for fuel; many monosaccharides and some disaccharides. Other carbohydrate types can be used, but only with the assistance of gut bacteria. Ruminants and termites, can even process cellulose, which is indigestible to other organisms.
Foods high in carbohydrates include breads, pastas, beans, potatoes, bran, rice and cereals. Most such foods are high in starch.
Based on the effects on risk of heart disease and obesity, the Institute of Medicine recommends that American and Canadian adults get between 40-65% of dietary energy from carbohydrates.[7] The Food and Agriculture Organization and World Health Organization jointly recommend that national dietary guidelines set a goal of 55-75% of total energy from carbohydrates, but only 10% directly from sugars (their term for simple carbohydrates).[8]
Classification
Dietitians and other certified food scientists commonly classify carbohydrates as simple (monosaccharides and disaccharides) or complex (oligosaccharides and polysaccharides). The term complex carbohydrate was first used in the Senate Select Committee publication Dietary Goals for the United States (1977), where it denoted "fruit, vegetables and whole-grains".[9] Dietary guidelines generally recommend that complex carbohydrates, and such nutrient-rich simple carbohydrate sources such as fruit (glucose or fructose) and dairy products (lactose) make up the bulk of carbohydrate consumption. This excludes such sources of simple sugars as candy and sugary drinks. The USDA's Dietary Guidelines for Americans 2005 dispensed with the simple/complex distinction, instead recommending fiber-rich foods and whole grains.[10]
The glycemic index and glycemic load concepts have been developed to characterize food behavior during human digestion. They rank carbohydrate-rich foods based on the rapidity of their effect on blood glucose levels. The insulin index is a similar, more recent classification method which ranks foods based on their effects on blood insulin levels, which are caused by glucose (or starch) and some amino acids in food. Glycemic index is a measure of how quickly food glucose is absorbed, while glycemic load is a measure of the total absorbable glucose in foods.
Metabolism
Main article: Carbohydrate metabolism
Please help improve this section by expanding it. Further information might be found on the talk page. (June 2008)
This section repeats, in whole or part, the text of other article(s) or section(s).
Please discuss this issue on the talk page and conform with Wikipedia's Manual of Style by replacing the section with a link and a summary of the repeated text, or by spinning off the repeated text into an article in its own right.
Catabolism
Catabolism is the metabolic reaction cells undergo in order to extract energy. There are two major metabolic pathways of monosaccharide catabolism:
Glycolysis
Citric acid cycle
Oligo/polysaccharides are cleaved first to smaller monosaccharides by enzymes called Glycoside hydrolases. The monosaccharide units can then enter into monosaccharide catabolism. In some cases, as with humans, not all carbohydrate types are usable as the digestive and metabolic enzymes necessary are not present. For instance, neither horses nor humans nor cats can digest and use cellulose, but ruminants and termites can.
Carbohydrate chemistry
Carbohydrates are reactants in many organic reactions. For example:
Carbohydrate acetalisation
Cyanohydrin reaction
Lobry-de Bruyn-van Ekenstein transformation
Amadori rearrangement
Nef reaction
Wohl degradation
Koenigs-Knorr reaction
See also
Wikimedia Commons has media related to: Carbohydrates
Biochemistry
Bioplastic
Gluconeogenesis
Glycolipid
Glycoprotein
Low-carbohydrate diet
No-carbohydrate diet
Macromolecules
Nutrition
Pentose phosphate pathway
Photosynthesis
Sugar
[show]v • d • eMetabolism
Catabolism - Anabolism
Metabolic pathway - Metabolic network - Cellular respiration (Anaerobic/Aerobic)
Protein metabolism - Carbohydrate metabolism - Lipid metabolism - Iron metabolism
[show]v • d • eFood chemistry
Additives · Carbohydrates · Coloring · Enzymes · Essential fatty acids · Flavors · Lipids · Minerals · Proteins · Vitamins · Water
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
References
^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59. ISBN 0-13-981176-1.
^ Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings. ISBN 0-8053-3066-6
^ Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall. ISBN 0-13-250882-6. http://www.phschool.com/el_marketing.html.
^ N.A.Campbell (1996) Biology (4th edition). Benjamin Cummings NY. p.23 ISBN 0-8053-1957-3
^ Is dietary carbohydrate essential for human nutrition? - Westman 75 (5): 951 - American Journal of Clinical Nutrition
^ A High-Protein, High-Fat, Carbohydrate-Free Diet Reduces Energy Intake, Hepatic Lipogenesis, and Adiposity in Rats - Pichon et al. 136 (5): 1256 - Journal of Nutrition
^ Food and Nutrition Board (2002/2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press. Page 769. ISBN 0-309-08537-3
^ Joint WHO/FAO expert consultation (2003). Diet, Nutrition and the Prevention of Chronic Diseases (PDF). Geneva: World Health Organization. Pages 55-56. ISBN 92-4-120916-X
^ Joint WHO/FAO expert consultation (1998), Carbohydrates in human nutrition, chapter 1. ISBN 92-5-104114-8.
^ DHHS and USDA, Dietary Guidelines for Americans 2005, Chapter 7 Carbohydrates
External links
Carbohydrates, including interactive models and animations (Requires MDL Chime)
IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN): Carbohydrate Nomenclature
Carbohydrates detailed
Carbohydrates and Glycosylation - The Virtual Library of Biochemistry and Cell Biology
Consortium for Functional Glycomics
[show]v • d • eTypes of Carbohydrates
General: Aldose · Ketose · Pyranose · Furanose
Geometry Cyclohexane conformation · Anomer · Mutarotation
Monosaccharides Trioses Ketotriose (Dihydroxyacetone) · Aldotriose (Glyceraldehyde)
Tetroses Ketotetrose (Erythrulose) · Aldotetroses (Erythrose, Threose)
Pentoses Ketopentose (Ribulose, Xylulose)
Aldopentose (Ribose, Arabinose, Xylose, Lyxose)
Deoxy sugar (Deoxyribose)
Hexoses Ketohexose (Psicose, Fructose, Sorbose, Tagatose)
Aldohexose (Allose, Altrose, Glucose, Mannose, Gulose, Idose, Galactose, Talose)
Deoxy sugar (Fucose, Fuculose, Rhamnose)
Heptose Sedoheptulose
Multiple Disaccharides Sucrose · Lactose · Maltose · Trehalose · Turanose · Cellobiose
Trisaccharides Raffinose · Melezitose · Maltotriose
Tetrasaccharides Acarbose · Stachyose
Other oligosaccharides Fructooligosaccharide (FOS) · Galacto-oligosaccharide (GOS) · Mannan-oligosaccharides (MOS)
Polysaccharide Glucose: Glycogen · Starch (Amylose, Amylopectin) · Cellulose · Dextrin · Glucan (Beta-glucan)
Fructose: Fructan (Inulin, Levan beta 2→6)
N-Acetylglucosamine: Chitin
Glycosaminoglycans Heparin · Chondroitin sulfate · Hyaluronan · Heparan sulfate · Dermatan sulfate · Keratan sulfate
Aminoglycosides Kanamycin · Streptomycin · Tobramycin · Neomycin · Paromomycin · Apramycin · Gentamicin · Netilmicin · Amikacin
Major families of biochemicals
Saccharides · Carbohydrates · Glycosides · · Amino acids · Peptides · Proteins · Glycoproteins · · Lipids · Terpenes · Steroids · Carotenoids
Alkaloids · Nucleobases · Nucleic acids · · Enzyme cofactors · Flavonoids · Polyketides · Tetrapyrroles
Retrieved from "http://en.wikipedia.org/wiki/Carbohydrate"
Categories: Duplicate Articles | Carbohydrates | Nutrition
Hidden categories: Semi-protected against vandalism | Articles to be expanded since June 2008 | All articles to be expanded
ViewsArticle Discussion View source History Personal toolsLog in / create account Navigation
Monday, November 24, 2008
燕窝的医药药理作用与临床应用
【 燕窝的医药药理作用与临床应用】
1、“美容基因”——表皮生长因子在大约一百年前，德国化学家费雪（Emilfischer）已证明蛋白质的氨基酸相互结合成多肽链，如两个甘氨酸脱去一分子水后形成甘氨酸。生长的键称为胜肽键。如果继续进行反应，可生成含有许多氨基酸残基的多肽。在动植物及细菌中有许多低分子多肽，它们具有非常重要的生理作用。多肽类激素就是其中很重要性的一类。有学者研究发现，燕窝中就含有一种非常重要的多肽类激素——表皮生长因子（epidermicgrowthfactor，简称EGF）。这种物质在人体的绝大多数体液中存在，在乳汁、精液等中的含量尤高。在人体内，它主要由颌下腺、十二指肠腺合成，有多种重要的生理功能，如抑制胃酸的分泌、保护十二指肠等。EGF还有一项非常重要的功能，并因此被誉为“美容基因”。它能刺激多种细胞的分裂增殖，促进细胞分化，对受损皮肤进行快速修复，促进手术创口和创面的愈合；它能影响人体皮肤的细腻和老化，能启动衰老皮肤的细胞，使皮肤变得光滑而有弹性。上述发现，不仅为全世界女性朋友的福音。其实，多年来，港台地区许多当红的影视明星，尤其是女明星们，一直对燕窝是宠爱有加，在排戏或演唱会的繁重工作压力下，燕窝成了她们护肤养颜、永葆青春的亲密伴侣。这些透过各种媒体的渲染，早已成了公开的秘密了。现在看来，燕窝在美容护肤方面的神奇功效，不仅有大量的实践经验可资证明，也确确实实是有其科学基础的。能提高免疫功能的促有丝分裂原学者们还从燕窝中提取出一种被称为促进T细胞或B细胞分裂。我们知道，淋巴细胞是人体内重要的免疫细胞，它主要包括T淋巴细胞和B淋巴细胞。燕窝中的这种促有丝分裂原，能透过刺激淋巴细胞的有丝分裂，提高人体的免疫功能。这或许也就是燕窝滋补强身功能的物质基础吧。
2、对呼吸系统疾病的治疗作用对呼吸系统疾病的治疗作用，可以说是燕窝的经典疗效了。从古至今，各种医籍无不强调燕窝对呼吸系统（古时称为肺系）疾病的治疗作用，如痨瘵、咳嗽、咯血、痰喘等等，也就是今天所说的肺结核、气管炎、支气管炎等病。这在前面的章节中已有介绍。另外，对于有吸烟的不良嗜好的人来说，燕窝是不可多得的“洗肺”佳品。在中国曾有学者指出，用燕窝为主要药物制成的复方燕窝汤，治疗了五百余位慢性支气管炎病人，取得了非常显著的临床疗效。也进一步验证了古书中对燕窝疗效的描述。
3、预防肿瘤，减少放化疗不良反应目前，恶性肿瘤仍严重威协着人类的健康。全世界的医务工作者都在为最终降伏癌魔进行着不懈的努力。现在可以肯定的是，“三早”（即早预防、早诊断、早治疗）是降低癌症的发病率、死亡率和提高癌症患者生存率的有效措施。其中，早预防是最积极和有效的方法。正常细胞在致癌因素作用下转变为癌细胞需要相当长的一段时间，即使在当今这个环境污染日益严重的社会，有60%-80%的癌症仍是可以预防的。中医有句名言：“正气存内，邪不可干。”也就是说，当人体健康状况良好、抵抗力强的时候，各种致病因素是很难侵入人体而发病的。而采自纯天然环境的野生燕窝，完全可以提高人体免疫力的作用，达到预防癌症的目的。对于未经治疗的癌症患者来说，此时选择燕窝是不恰当的，说得严重一点，无疑于抱薪救火。癌症的治疗措施，无非是手术、放疗、化疗。在完成这些治疗方法后，病人往往身体虚弱，免疫力低下，此时再投以有良好滋补作用的燕窝，那简直就是雪中送炭了。例如，在二十世纪八十年代，香港的学者研究发现，燕窝能增强人体对X射线及其他放射线损害的抵御能力，这为燕窝应用于癌症放疗患者提供了强有力的理论基础。
4、强心、降压作用日本有位学者藤冈睦，他为了研究燕窝的药理作用，曾经进行了这样的一个动物实验：将小狗麻醉后，连通人工呼吸机，将小狗开胸后，在小狗的心脏内安放各种测量仪器，以便记录小狗的心脏收缩力和血压。然后将燕窝的提取物应用于小狗，观察应用后小狗心率，心脏收缩力和血压的变化。结果发现，燕窝的提取物对小狗的心率没有什么影响，但是可以显著地增强小狗的心脏收缩力，因此可以认为燕窝的提取物具有强心的作用。而且，从一定的剂量开始，燕窝的提取物就显示出降血压的作用，并且是特定性地作用于舒张期血压，也就是通常所说的低压。有高血压的朋友都知道，相对而言，收缩压的降低要更难一些。目前，心脑血管疾病已经成为危害人类健康的头号杀手，燕窝的这种强心、降压（尤其是降低舒张压）作用，将带给人类更多的希望。
5、抗氧化，防衰老最新的医学研究证明，燕窝是一种抗氧化食品，具有排毒功效，长期食用可达到延缓衰老的目的。衰老是人的身体随着年龄的增长，而逐渐产生的一系列形态结构和生理功能的退化过程，是生命活动的自然规律。但是，如果能正确掌握衰老的客观规律，选择和创造有利条件，就可以延缓衰老，益寿延年。衰老的过程伴随的是一系列生物体功能的减退。老年人的免疫功能明显下降，主要表现为免疫监视功能降低，细胞免疫功能下降，淋巴细胞的分裂、增殖能力减退，致使免疫调节功能低下，衰老加快。现代医学研究已经证实，人的衰老与体内自由基的关系极为密切。自由基代谢及其清除系统平衡失调，修复遗传物质损伤的功能减退，负责清除自由基的超氧化物歧化酶的活性降低，生物新陈代谢过程中产生的超氧会离子自由基、羟自由基等不能被有效地清除，可能使生物膜的不饱和脂肪酸发生氧化而影响结构，攻击蛋白质使之发生交联而改变了酢的功能，进而损伤DNA引起突变，加速衰老。燕窝及其提取物，一方面具有增强免疫功能，另一方面，又具有抗氧化作用，在预防衰老方面有很强的对抗性，因此也具有非常神奇的功效。对此最有体会的，大概就是那些影视歌坛成名已久的女明星们了。
6、抗疲劳作用疲劳，是当今社会许多人的共同感受。生活节奏的日益加快，令人喘不过气的工作压力，又怎能是一个“累”字了得？普通人活得已经很累，更不要说那些明星们了。燕窝的抗疲劳作用，已经从那些所谓的明星们那里得到了很好的印证。在娱乐新闻中，你很容易看到某明星在演唱会后或拍片之余，吃燕窝以保持精力的报导。在中国卫生部一九九九年批准的保健食品店品目录中，就有西洋参燕窝口服液，而批准的功能就是抗疲劳！燕窝生长环境对人体的良性调节作用环境和可持续发展问题，已成为当今最困扰地球人类的问题。由环境污染带来的对人类健康的负面影响是触目惊心的。地球拒绝污染，人类呼唤绿争。而“养在深闺”的燕窝，就非常符合人类的“绿色”理念。燕窝大多生长在远离人类居住区的海边洞穴里恒湿、低杂讯、空气清新、含有较多的负离子；而且知人类自下而上环境污染越来越严重的今天，人迹罕至的洞穴中，有害微生物与放射性元素含量要远远低于地面的大气环境，在这种优良环境中出产的燕窝，无疑能给一些疾病患者提供了改善生理、心理状况和治病的优良条件。
7、孕产期保健之佳品根据报导，在新加坡，有一半以上的孕妇食用各种燕窝制品，以确保未来的宝宝更健康，避免让自己的宝宝输在起跑点上。事实证明，孕妇在生产前两三个月食用燕窝，不仅能使母亲身体强健，而且能使未来的新生婴儿更强壮、更白皙、更漂亮、更不易生病。产后的妇女，要缓解哺育孩子的劳累，要恢复生产前窈窕的身姿，燕窝是最佳的天然滋补食品。其性味甘、平，对孕妇和产后妇女而言，补而不腻，没有任何不良反应。
8、其他的功效其余有媒体报导的燕窝作用有：
a.抗衰老，改善血液循环，对中老年人体力、精神活力、记忆力及生理功能的衰退有明显疗效。
b.护肤养颜，令皮肤滑润洁白，减少脸部皱纹，清除暗疮。补血活血，去瘀生新，对妇女经期不适、经痛、月经过多有良好疗效。产后服用可促进子宫及体型复原。
c.降低胆固醇，对高血压脑血管闭塞的心绞痛、胸闷、气促有良好的防治作用。
d.壮腰健肾，治疗腰骨及四肢关节酸痛、风湿性关节炎、手足麻痹、头错眼花及飞蚊症有效。
e.消除因学业或工作压力产生的疲劳，增强记忆力。
f.增强身体抵抗力，预防伤风感冒，治疗身体虚弱、痰喘咳嗽。
g.对B型肝炎、肝硬化有一定的疗效。
1、“美容基因”——表皮生长因子在大约一百年前，德国化学家费雪（Emilfischer）已证明蛋白质的氨基酸相互结合成多肽链，如两个甘氨酸脱去一分子水后形成甘氨酸。生长的键称为胜肽键。如果继续进行反应，可生成含有许多氨基酸残基的多肽。在动植物及细菌中有许多低分子多肽，它们具有非常重要的生理作用。多肽类激素就是其中很重要性的一类。有学者研究发现，燕窝中就含有一种非常重要的多肽类激素——表皮生长因子（epidermicgrowthfactor，简称EGF）。这种物质在人体的绝大多数体液中存在，在乳汁、精液等中的含量尤高。在人体内，它主要由颌下腺、十二指肠腺合成，有多种重要的生理功能，如抑制胃酸的分泌、保护十二指肠等。EGF还有一项非常重要的功能，并因此被誉为“美容基因”。它能刺激多种细胞的分裂增殖，促进细胞分化，对受损皮肤进行快速修复，促进手术创口和创面的愈合；它能影响人体皮肤的细腻和老化，能启动衰老皮肤的细胞，使皮肤变得光滑而有弹性。上述发现，不仅为全世界女性朋友的福音。其实，多年来，港台地区许多当红的影视明星，尤其是女明星们，一直对燕窝是宠爱有加，在排戏或演唱会的繁重工作压力下，燕窝成了她们护肤养颜、永葆青春的亲密伴侣。这些透过各种媒体的渲染，早已成了公开的秘密了。现在看来，燕窝在美容护肤方面的神奇功效，不仅有大量的实践经验可资证明，也确确实实是有其科学基础的。能提高免疫功能的促有丝分裂原学者们还从燕窝中提取出一种被称为促进T细胞或B细胞分裂。我们知道，淋巴细胞是人体内重要的免疫细胞，它主要包括T淋巴细胞和B淋巴细胞。燕窝中的这种促有丝分裂原，能透过刺激淋巴细胞的有丝分裂，提高人体的免疫功能。这或许也就是燕窝滋补强身功能的物质基础吧。
2、对呼吸系统疾病的治疗作用对呼吸系统疾病的治疗作用，可以说是燕窝的经典疗效了。从古至今，各种医籍无不强调燕窝对呼吸系统（古时称为肺系）疾病的治疗作用，如痨瘵、咳嗽、咯血、痰喘等等，也就是今天所说的肺结核、气管炎、支气管炎等病。这在前面的章节中已有介绍。另外，对于有吸烟的不良嗜好的人来说，燕窝是不可多得的“洗肺”佳品。在中国曾有学者指出，用燕窝为主要药物制成的复方燕窝汤，治疗了五百余位慢性支气管炎病人，取得了非常显著的临床疗效。也进一步验证了古书中对燕窝疗效的描述。
3、预防肿瘤，减少放化疗不良反应目前，恶性肿瘤仍严重威协着人类的健康。全世界的医务工作者都在为最终降伏癌魔进行着不懈的努力。现在可以肯定的是，“三早”（即早预防、早诊断、早治疗）是降低癌症的发病率、死亡率和提高癌症患者生存率的有效措施。其中，早预防是最积极和有效的方法。正常细胞在致癌因素作用下转变为癌细胞需要相当长的一段时间，即使在当今这个环境污染日益严重的社会，有60%-80%的癌症仍是可以预防的。中医有句名言：“正气存内，邪不可干。”也就是说，当人体健康状况良好、抵抗力强的时候，各种致病因素是很难侵入人体而发病的。而采自纯天然环境的野生燕窝，完全可以提高人体免疫力的作用，达到预防癌症的目的。对于未经治疗的癌症患者来说，此时选择燕窝是不恰当的，说得严重一点，无疑于抱薪救火。癌症的治疗措施，无非是手术、放疗、化疗。在完成这些治疗方法后，病人往往身体虚弱，免疫力低下，此时再投以有良好滋补作用的燕窝，那简直就是雪中送炭了。例如，在二十世纪八十年代，香港的学者研究发现，燕窝能增强人体对X射线及其他放射线损害的抵御能力，这为燕窝应用于癌症放疗患者提供了强有力的理论基础。
4、强心、降压作用日本有位学者藤冈睦，他为了研究燕窝的药理作用，曾经进行了这样的一个动物实验：将小狗麻醉后，连通人工呼吸机，将小狗开胸后，在小狗的心脏内安放各种测量仪器，以便记录小狗的心脏收缩力和血压。然后将燕窝的提取物应用于小狗，观察应用后小狗心率，心脏收缩力和血压的变化。结果发现，燕窝的提取物对小狗的心率没有什么影响，但是可以显著地增强小狗的心脏收缩力，因此可以认为燕窝的提取物具有强心的作用。而且，从一定的剂量开始，燕窝的提取物就显示出降血压的作用，并且是特定性地作用于舒张期血压，也就是通常所说的低压。有高血压的朋友都知道，相对而言，收缩压的降低要更难一些。目前，心脑血管疾病已经成为危害人类健康的头号杀手，燕窝的这种强心、降压（尤其是降低舒张压）作用，将带给人类更多的希望。
5、抗氧化，防衰老最新的医学研究证明，燕窝是一种抗氧化食品，具有排毒功效，长期食用可达到延缓衰老的目的。衰老是人的身体随着年龄的增长，而逐渐产生的一系列形态结构和生理功能的退化过程，是生命活动的自然规律。但是，如果能正确掌握衰老的客观规律，选择和创造有利条件，就可以延缓衰老，益寿延年。衰老的过程伴随的是一系列生物体功能的减退。老年人的免疫功能明显下降，主要表现为免疫监视功能降低，细胞免疫功能下降，淋巴细胞的分裂、增殖能力减退，致使免疫调节功能低下，衰老加快。现代医学研究已经证实，人的衰老与体内自由基的关系极为密切。自由基代谢及其清除系统平衡失调，修复遗传物质损伤的功能减退，负责清除自由基的超氧化物歧化酶的活性降低，生物新陈代谢过程中产生的超氧会离子自由基、羟自由基等不能被有效地清除，可能使生物膜的不饱和脂肪酸发生氧化而影响结构，攻击蛋白质使之发生交联而改变了酢的功能，进而损伤DNA引起突变，加速衰老。燕窝及其提取物，一方面具有增强免疫功能，另一方面，又具有抗氧化作用，在预防衰老方面有很强的对抗性，因此也具有非常神奇的功效。对此最有体会的，大概就是那些影视歌坛成名已久的女明星们了。
6、抗疲劳作用疲劳，是当今社会许多人的共同感受。生活节奏的日益加快，令人喘不过气的工作压力，又怎能是一个“累”字了得？普通人活得已经很累，更不要说那些明星们了。燕窝的抗疲劳作用，已经从那些所谓的明星们那里得到了很好的印证。在娱乐新闻中，你很容易看到某明星在演唱会后或拍片之余，吃燕窝以保持精力的报导。在中国卫生部一九九九年批准的保健食品店品目录中，就有西洋参燕窝口服液，而批准的功能就是抗疲劳！燕窝生长环境对人体的良性调节作用环境和可持续发展问题，已成为当今最困扰地球人类的问题。由环境污染带来的对人类健康的负面影响是触目惊心的。地球拒绝污染，人类呼唤绿争。而“养在深闺”的燕窝，就非常符合人类的“绿色”理念。燕窝大多生长在远离人类居住区的海边洞穴里恒湿、低杂讯、空气清新、含有较多的负离子；而且知人类自下而上环境污染越来越严重的今天，人迹罕至的洞穴中，有害微生物与放射性元素含量要远远低于地面的大气环境，在这种优良环境中出产的燕窝，无疑能给一些疾病患者提供了改善生理、心理状况和治病的优良条件。
7、孕产期保健之佳品根据报导，在新加坡，有一半以上的孕妇食用各种燕窝制品，以确保未来的宝宝更健康，避免让自己的宝宝输在起跑点上。事实证明，孕妇在生产前两三个月食用燕窝，不仅能使母亲身体强健，而且能使未来的新生婴儿更强壮、更白皙、更漂亮、更不易生病。产后的妇女，要缓解哺育孩子的劳累，要恢复生产前窈窕的身姿，燕窝是最佳的天然滋补食品。其性味甘、平，对孕妇和产后妇女而言，补而不腻，没有任何不良反应。
8、其他的功效其余有媒体报导的燕窝作用有：
a.抗衰老，改善血液循环，对中老年人体力、精神活力、记忆力及生理功能的衰退有明显疗效。
b.护肤养颜，令皮肤滑润洁白，减少脸部皱纹，清除暗疮。补血活血，去瘀生新，对妇女经期不适、经痛、月经过多有良好疗效。产后服用可促进子宫及体型复原。
c.降低胆固醇，对高血压脑血管闭塞的心绞痛、胸闷、气促有良好的防治作用。
d.壮腰健肾，治疗腰骨及四肢关节酸痛、风湿性关节炎、手足麻痹、头错眼花及飞蚊症有效。
e.消除因学业或工作压力产生的疲劳，增强记忆力。
f.增强身体抵抗力，预防伤风感冒，治疗身体虚弱、痰喘咳嗽。
g.对B型肝炎、肝硬化有一定的疗效。
Thursday, November 20, 2008
Sunday, November 2, 2008
Friday, October 31, 2008
燕窝润肤液燕窝润肤液提取自燕窝, 该浓缩液富含糖，氨基酸和矿物盐，其有效建立皮肤胶原蛋白的愈合和防止皱纹的形成，使皮肤永葆青春，焕发光彩。此外，它也通过水溶性维生素E和抗氧化剂，保护我们的皮肤免受有害自由基和水的流失，保持皮肤水分平衡。该浓缩液通过加速细胞的生长、增强皮肤免疫力，从而维持健康和美丽的皮肤，促使容光焕发。
成分:
燕窝提取物，羧甲基纤维素钠，钠乙二胺四乙酸，尿囊素，Glucono Delta Lactone,柠檬酸钠，透明质酸钠，甘草提取物，甘油，维生素E ，黄瓜提取液，乳酸钠， Lactofemine, 2-phenoxyethanol (and) 2-Methyl-4-Isothiazolin-3-one, 香水, Polysorbate 80, Deionised Water.
更多咨询 www.yongkangbirdnest.com
燕窝抗衰老霜 燕窝抗衰老霜提取自昂贵燕窝，富含糖蛋白、氨基酸和矿物盐，所含成分能够促使皮肤胶原蛋白的愈合和防止皱纹，焕发皮肤青春光采。
它富含维生素E，一种众所周知的抗氧化剂能够保护我们的皮肤免受有害自由基损伤和水份的流失。这细致的面霜让你的皮肤健康和美丽，因为它加速细胞的生长，激发和加强你的皮肤免疫力，使皮肤更加细腻光滑，容光焕发。
成分:
鸟巢提取物， Sobitol ，甘油，乳酸钠， Cyclopentasiloxane ，透明质酸钠，尿囊素，维生素E ，香水， Lactoferrine ， C12-C15烷基苯甲酸，氧化玉米油, 2-Phenoxyethanol (and) 2- Methyl-4-Isothiazolin-3-one,二氧化钛, Hydrogenated, Polydecene, Hydroxystearic Acid,丙烯酸酯钠, Copolymer and Paraffium Liquidum with PPG-1 trideceth-6, Deionised Water.
详细资料请游览 www.yongkangbirdnest.com
永康燕窝科学研究报告
营养研究成分
灰份 0.5 – 0.7 %
纤维 0.5 – 0.7 %
蛋白质 56.7 – 63.5 %
脂肪 0.5 – 1. %
潮湿 ±.10 %
碳水化合物 20.1 – 25.7 %
- 永康燕窝拥有17 种氨基酸可帮助细胞和皮肤组织再生
- 永康燕窝蛋白在于150-40 kD 且拥有非常明显的145和 100kD蛋白燕窝功效和营养价值燕窝含有丰富的氨基酸与活性蛋白。这活性蛋白拥有表皮生长因子，可刺激细胞生长。燕窝也相信可滋补养颜，使之容光焕发。根据中国大辞典的记载：
1. 燕窝功能可益气，润肺，开胃，止咳，治血痢。
2. 燕窝含多种水溶性氨基酸，婴儿和孩童常吃能长智慧，抗敏感，中气充足。
3. 孕妇在怀孕期间，产前产后进食，则有安胎，补胎之效。
4. 燕窝是碱性液，对食道癌，咽喉癌，胃癌，肝癌，直肠癌等有抑制和抗衡作用。
5. 凡经电疗，化疗而引起的后遗症，食燕窝都有明显的改善。
6. 使人皮肤光滑，有弹性和光泽，从而减少皱纹。
更多咨询查询 www.yongkangbirdnest.com
营养研究成分
灰份 0.5 – 0.7 %
纤维 0.5 – 0.7 %
蛋白质 56.7 – 63.5 %
脂肪 0.5 – 1. %
潮湿 ±.10 %
碳水化合物 20.1 – 25.7 %
- 永康燕窝拥有17 种氨基酸可帮助细胞和皮肤组织再生
- 永康燕窝蛋白在于150-40 kD 且拥有非常明显的145和 100kD蛋白燕窝功效和营养价值燕窝含有丰富的氨基酸与活性蛋白。这活性蛋白拥有表皮生长因子，可刺激细胞生长。燕窝也相信可滋补养颜，使之容光焕发。根据中国大辞典的记载：
1. 燕窝功能可益气，润肺，开胃，止咳，治血痢。
2. 燕窝含多种水溶性氨基酸，婴儿和孩童常吃能长智慧，抗敏感，中气充足。
3. 孕妇在怀孕期间，产前产后进食，则有安胎，补胎之效。
4. 燕窝是碱性液，对食道癌，咽喉癌，胃癌，肝癌，直肠癌等有抑制和抗衡作用。
5. 凡经电疗，化疗而引起的后遗症，食燕窝都有明显的改善。
6. 使人皮肤光滑，有弹性和光泽，从而减少皱纹。
更多咨询查询 www.yongkangbirdnest.com
你知道市场上95%的燕窝都含有毒化学物质吗？
经过中国毒奶事件后，你还相信自己看了就能分辨燕窝的真假吗？
一小瓶的矿泉水都有标签，请问你有看过燕窝的验证标签吗？
在一个很偶然的情况下认识了大学微生物及食品保鲜专家。在他的的指引下，了解了市场燕窝的品质。可以说95%的燕窝都掺了有毒的化学物质.
由于无知用了漂白水破坏了燕窝珍贵的水溶性氨基酸，表皮生长因子（EGF），另外也加了防腐剂或色素和添加剂。
对燕窝的认知，打从心里就有一个使命了，就是打着健康燕窝文化。
一小瓶的矿泉水都有标签，请问你有看过燕窝的验证标签吗？
在一个很偶然的情况下认识了大学微生物及食品保鲜专家。在他的的指引下，了解了市场燕窝的品质。可以说95%的燕窝都掺了有毒的化学物质.
由于无知用了漂白水破坏了燕窝珍贵的水溶性氨基酸，表皮生长因子（EGF），另外也加了防腐剂或色素和添加剂。
对燕窝的认知，打从心里就有一个使命了，就是打着健康燕窝文化。
Subscribe to:
Posts (Atom)
