1. Carbohydrates

2. Outline Nature of carbohydrates Nature of carbohydrates Classes of carbohydrates Classes of carbohydrates Functions of carbohydrates Functions of carbohydrates Food sources of carbohydrates Food sources of carbohydrates Body needs for carbohydrates Body needs for carbohydrates

3. Nature of carbohydrates Energy production system: Energy production system: - 3 steps to produce energy from a basic fuel supply: - 3 steps to produce energy from a basic fuel supply: (1) In human body, the body digests its basic fuel, carbohydrates, changing it to glucose. (2) The body then absorb & through blood circulation, carries this refined fuel to cells that need glucose. (3) Glucose is burned in these cells, & energy produced through the process of metabolism.

4. Nature of carbohydrates The carbohydrates are a group of naturally occurring carbonyl compounds (aldehydes or ketones) that also contain several hydroxyl groups. The carbohydrates are a group of naturally occurring carbonyl compounds (aldehydes or ketones) that also contain several hydroxyl groups. A carbohydrates is composed of carbon (C), hydrogen (H), and oxygen (O). A carbohydrates is composed of carbon (C), hydrogen (H), and oxygen (O). (CH 2 O) n when n = 5 then C 5 H 10 O 5 (CH 2 O) n when n = 5 then C 5 H 10 O 5 Glucose is the most important carbohydrate; most dietary carbohydrate is absorbed into the bloodstream as glucose, and other sugars are converted into glucose in the liver. Glucose is the most important carbohydrate; most dietary carbohydrate is absorbed into the bloodstream as glucose, and other sugars are converted into glucose in the liver.

5. Classes of carbohydrates It is taken up by the cells and either broken down to obtain energy (glycolysis) or converted into other metabolites. It is taken up by the cells and either broken down to obtain energy (glycolysis) or converted into other metabolites. Glucose is the major metabolic fuel of mammals and a universal fuel of the fetus. It is the precursor for synthesis of all the other carbohydrates in the body, including glycogen for storage; ribose and deoxyribose in nucleic acids; and galactose in lactose of milk, in glycolipids, and in combination with protein in glycoproteins and proteoglycans. Glucose is the major metabolic fuel of mammals and a universal fuel of the fetus. It is the precursor for synthesis of all the other carbohydrates in the body, including glycogen for storage; ribose and deoxyribose in nucleic acids; and galactose in lactose of milk, in glycolipids, and in combination with protein in glycoproteins and proteoglycans. Diseases associated with carbohydrate metabolism include diabetes mellitus, galactosemia, glycogen storage diseases, and lactose intolerance. Diseases associated with carbohydrate metabolism include diabetes mellitus, galactosemia, glycogen storage diseases, and lactose intolerance. CARBOHYDRATES ARE ALDEHYDE OR KETONE DERIVATIVES OF POLYHYDRIC ALCOHOLS CARBOHYDRATES ARE ALDEHYDE OR KETONE DERIVATIVES OF POLYHYDRIC ALCOHOLS

6. Classes of carbohydrates Monosaccharide: Monosaccharide: Are those carbohydrates that cannot be hydrolyzed into simpler carbohydrates: They may be classified as trioses, tetroses, pentoses, hexoses, or heptoses, depending upon the number of carbon atoms; and as aldoses or ketoses depending upon whether they have an aldehyde or ketone group. Examples are listed in Table 1. –They are quickly absorbed from the intestine into the blood stream and carried to the liver. –Glucose, fructose, lactose.

7. Classes of carbohydrates Disaccharide: Are condensation products of two monosaccharide units. Disaccharide: Are condensation products of two monosaccharide units. - Sucrose, Lactose, Maltose. - Sucrose, Lactose, Maltose. Oligosaccharides: Are condensation products of more than two to ten monosaccharides; maltotriose is an example Oligosaccharides: Are condensation products of more than two to ten monosaccharides; maltotriose is an example Polysaccharide: Are condensation products of more than ten monosaccharide units; examples are the starches and dextrins, which may be linear or branched polymers. Polysaccharide: Are condensation products of more than ten monosaccharide units; examples are the starches and dextrins, which may be linear or branched polymers. - Starch, Glycogen, Dietary fiber. - Starch, Glycogen, Dietary fiber.

8. Monosaccharide Glucose: Glucose: - Is the form of sugar circulating in the blood and is the primary fuel to the cells. - Is the form of sugar circulating in the blood and is the primary fuel to the cells. - The blood supply comes mainly from the digestion of starch, & sometimes called dextrose. - The blood supply comes mainly from the digestion of starch, & sometimes called dextrose. - Is a moderately sweet sugar. - Is a moderately sweet sugar. Fructose: is found mainly in fruits, consider the sweetest of the simple sugars. Fructose: is found mainly in fruits, consider the sweetest of the simple sugars. Galactose: comes mainly from the digestion of milk sugar, or lactose. Galactose: comes mainly from the digestion of milk sugar, or lactose.

9. Disaccharides Sucrose: Sucrose: - Is common table sugar, its two sugar units are glucose & fructose. - Is common table sugar, its two sugar units are glucose & fructose. Lactose: Lactose: - Is the milk sugar, formed in mammary glands - Is the milk sugar, formed in mammary glands - Its two single sugar units are glucose & Galactose. - Its two single sugar units are glucose & Galactose. - Not found in plants. - Not found in plants. - Aids in the absorption of calcium & phosphorus. - Aids in the absorption of calcium & phosphorus. Maltose: Maltose: - The two single sugar units that compose maltose are double glucose molecule, occurs as a breakdown product of the starches contained in malt (“malt sugar” and as an intermediate in the digestion of starch. - The two single sugar units that compose maltose are double glucose molecule, occurs as a breakdown product of the starches contained in malt (“malt sugar” and as an intermediate in the digestion of starch.

10. Polysaccharides Polysaccharides are sometimes classified as hexosans or pentosans, depending upon the identity of the constituent monosaccharides. Polysaccharides are sometimes classified as hexosans or pentosans, depending upon the identity of the constituent monosaccharides. Starch and glycogen are storage polymers of glucose in plants and animals, respectively. Starch and glycogen are storage polymers of glucose in plants and animals, respectively. Starch is the major source of energy in the diet. Starch is the major source of energy in the diet.

11. Polysaccharides 1) Starch: 1) Starch: - They are found in grains, legumes, and other vegetables, and some fruits. - They are found in grains, legumes, and other vegetables, and some fruits. - Breakdown more slowly and supply energy over a longer period of time. - Breakdown more slowly and supply energy over a longer period of time. - Most important dietary carbohydrate - Most important dietary carbohydrate - The major food sources of starch include grains in the form of pasta, crackers, bread, and other baked goods, legumes in the form of beans, & peas, potatoes, rice, corn, & bulgur. - The major food sources of starch include grains in the form of pasta, crackers, bread, and other baked goods, legumes in the form of beans, & peas, potatoes, rice, corn, & bulgur.

12. Polysaccharides - Whole grains: is used for food products such as flours, breads, or cereals that are produced from unrefined grain, which is grain that still retains its outer bran layers and inner germ endosperm and their nutrients (i.e. dietary fiber, minerals, & vitamins) - Whole grains: is used for food products such as flours, breads, or cereals that are produced from unrefined grain, which is grain that still retains its outer bran layers and inner germ endosperm and their nutrients (i.e. dietary fiber, minerals, & vitamins) - Enriched grains: are refined grain products to which key nutrients, usually minerals (i.e. iron), and vitamins (i.e. A, C, D, thiamin, riboflavin, & niacin), have been added. - Enriched grains: are refined grain products to which key nutrients, usually minerals (i.e. iron), and vitamins (i.e. A, C, D, thiamin, riboflavin, & niacin), have been added. 2) Glycogen: found in animal muscle tissue, and liver 2) Glycogen: found in animal muscle tissue, and liver 3) Dietary fiber 3) Dietary fiber

13. Polysaccharides: Dietary fiber Dietary fiber: in humans there is a lack in the necessary enzymes to digest dietary fiber, used to treat gastrointestinal problems. Dietary fiber: in humans there is a lack in the necessary enzymes to digest dietary fiber, used to treat gastrointestinal problems. - Cellulose: helps move the food mass along, stimulates normal muscle action in the intestine, the main sources are the stems and leaves of vegetables and the coverings of seeds and grains. - Cellulose: helps move the food mass along, stimulates normal muscle action in the intestine, the main sources are the stems and leaves of vegetables and the coverings of seeds and grains. - Noncellulose polysaccharides: they absorb water and swell to a larger bulk, thus slowing the emptying of the food mass from the stomach, and preventing spastic colon. - Noncellulose polysaccharides: they absorb water and swell to a larger bulk, thus slowing the emptying of the food mass from the stomach, and preventing spastic colon. - Lignin: is a large compound that forms the woody part of certain plants, it also combines with bile acids and cholesterol in the human intestine, preventing their absorption - Lignin: is a large compound that forms the woody part of certain plants, it also combines with bile acids and cholesterol in the human intestine, preventing their absorption

14. Complex carbohydrates: Contain other sugar derivatives such as amino sugars, uronic acids, and sialic acids. Contain other sugar derivatives such as amino sugars, uronic acids, and sialic acids. They include proteoglycans and glycosaminoglycans, associated with structural elements of the tissues; and glycoproteins, proteins containing attached oligosaccharide chains. They include proteoglycans and glycosaminoglycans, associated with structural elements of the tissues; and glycoproteins, proteins containing attached oligosaccharide chains. They are found in many situations including the cell membrane. They are found in many situations including the cell membrane.

15. Other sweeteners Used as sugar replacers Used as sugar replacers 2 types: 2 types: 1) Nutritive sweeteners: - They are sweeteners such sugar alcohols that contribute to total calorie intake. - They are sweeteners such sugar alcohols that contribute to total calorie intake. - Sugar alcohols (sorbitol, mannitol, & xylitol) - Sugar alcohols (sorbitol, mannitol, & xylitol) - 2-3 kcalories/gram. - 2-3 kcalories/gram. - Sorbitol: sucrose substitute. - Sorbitol: sucrose substitute. - They are absorbed slowly in the small intestine. - They are absorbed slowly in the small intestine. - Use for diabetic patients - Use for diabetic patients - Excessive amount= diarrhea. - Excessive amount= diarrhea. - lowered risk than sugar to cause dental caries. - lowered risk than sugar to cause dental caries.

16. Other sweeteners 2) Nonnutritive sweeteners: - Alternative sweeteners. - Alternative sweeteners. - Are sugar substitutes that do not have any caloric value. - Are sugar substitutes that do not have any caloric value. - Sweet taste without energy. - Sweet taste without energy. - Commonly used are aspartame & saccharin. - Commonly used are aspartame & saccharin. - Sweeter than table sugar. - Sweeter than table sugar.

17. Functions of carbohydrates 1) Primary energy function: 1) Primary energy function: (a) Basic fuel supply: (a) Basic fuel supply: - Primary fuel for the body. - Primary fuel for the body. - Fuel factor for carbohydrates is 4 kcal/gram. - Fuel factor for carbohydrates is 4 kcal/gram. (b) Reserve of fuel supply: (b) Reserve of fuel supply: - Glycogen reserves fuel supply - Glycogen reserves fuel supply - Individual must eat carbohydrate foods regularly to meet energy demand (to maintain blood glucose level & prevent a breakdown of fat and protein in tissue). - Individual must eat carbohydrate foods regularly to meet energy demand (to maintain blood glucose level & prevent a breakdown of fat and protein in tissue).

18. Functions of carbohydrates 2) Special tissue functions: 2) Special tissue functions: - Liver: glycogen reserves in the liver & muscles, protect cells from depressed metabolic function. - Liver: glycogen reserves in the liver & muscles, protect cells from depressed metabolic function. - Protein & fat: (1) Carbohydrates protects protein to be used in tissue growth & maintenance (2) Prevent rapid breakdown of fat & produce ketones (strong acid), this action called antiketogenic effect. - Protein & fat: (1) Carbohydrates protects protein to be used in tissue growth & maintenance (2) Prevent rapid breakdown of fat & produce ketones (strong acid), this action called antiketogenic effect.

19. Functions of carbohydrates 2) Special tissue functions: 2) Special tissue functions: - Heart: fatty acids are the regular fuel for energy, in emergency situation glycogen. - Heart: fatty acids are the regular fuel for energy, in emergency situation glycogen. - Central nervous system: the brain need continues supply of glucose, otherwise low sugar cause brain damage. - Central nervous system: the brain need continues supply of glucose, otherwise low sugar cause brain damage.

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