CarbohydratesCarbohydrates

King Saud UniversityKing Saud University

Al-Riyadh Community collegeAl-Riyadh Community college

By: Murad Adnan SawalhaBy: Murad Adnan Sawalha

OutlineOutline

• Nature of carbohydratesNature of carbohydrates• Classes of carbohydratesClasses of carbohydrates - Simple carbohydrates - Simple carbohydrates

(monosaccharide, disaccharides)(monosaccharide, disaccharides) - Complex carbohydrates - Complex carbohydrates (polysaccharides)(polysaccharides)• Functions of carbohydratesFunctions of carbohydrates• Food sources of carbohydratesFood sources of carbohydrates• Digestion of carbohydratesDigestion of carbohydrates• Body needs for carbohydratesBody needs for carbohydrates

Nature of carbohydratesNature of carbohydrates• Basic fuel source:Basic fuel source: - Energy is the power an organism requires to - Energy is the power an organism requires to

do work, this energy system must have a basic do work, this energy system must have a basic fuel supply.fuel supply.

- Photosynthesis: transform solar energy into - Photosynthesis: transform solar energy into carbohydrates (the stored fuel form of plants.carbohydrates (the stored fuel form of plants.

- Because the human body can quickly - Because the human body can quickly breakdown sugars & starches, they provide the breakdown sugars & starches, they provide the major sources of energy, in the form of calories.major sources of energy, in the form of calories.

- “Quick energy” foods. - “Quick energy” foods.

Nature of carbohydratesNature of carbohydrates• Energy production system: Energy production system: - 3 steps to produce energy from a basic fuel - 3 steps to produce energy from a basic fuel

supply:supply: 1) Change the basic fuel to a refined fuel that the 1) Change the basic fuel to a refined fuel that the

machine is designed to use.machine is designed to use. 2) Carry this refined fuel to the places that need it.2) Carry this refined fuel to the places that need it. 3) Burn this refined fuel in the special equipment 3) Burn this refined fuel in the special equipment

set up at these places.set up at these places.

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

Nature of carbohydratesNature of carbohydrates

• Dietary importance:Dietary importance: - Carbohydrates are widely available & easily - Carbohydrates are widely available & easily

growngrown

- Low cost in comparison with other food items.- Low cost in comparison with other food items.

- Easily stored, & they can be kept for long periods - Easily stored, & they can be kept for long periods without spoilage.without spoilage.

- Most of the total Kcalories in our diet come from - Most of the total Kcalories in our diet come from carbohydrates.carbohydrates.

Classes of carbohydratesClasses of carbohydrates• A carbohydrates is composed of carbon (C), hydrogen A carbohydrates is composed of carbon (C), hydrogen

(H), and oxygen (O).(H), and oxygen (O).

• (CH(CH22O)O)n n when n = 5 then Cwhen n = 5 then C55HH1010OO55

• Saccharide: chemical name for sugar molecules comes Saccharide: chemical name for sugar molecules comes from the Latin word saccharum, meaning “sugar”.from the Latin word saccharum, meaning “sugar”.

• Carbohydrates: are classified according to the number Carbohydrates: are classified according to the number of sugar, or Saccharide units.of sugar, or Saccharide units.

Classes of carbohydratesClasses of carbohydrates

• Monosaccharide: single (mono) molecules of Monosaccharide: single (mono) molecules of sugar, one sugar unit.sugar, one sugar unit.– They are quickly absorbed from the intestine into the They are quickly absorbed from the intestine into the

blood stream and carried to the liver.blood stream and carried to the liver.– Glucose, fructose, lactose.Glucose, fructose, lactose.

• Disaccharide: “double sugar” composed of 2 sugar Disaccharide: “double sugar” composed of 2 sugar unit.unit.

- Sucrose, Lactose, Maltose.- Sucrose, Lactose, Maltose.

• Polysaccharide: carbohydrates consisting of many Polysaccharide: carbohydrates consisting of many (poly) sugar molecules.(poly) sugar molecules.

- Starch, Glycogen, Dietary fiber.- Starch, Glycogen, Dietary fiber.

Monosaccharide Monosaccharide • Glucose: Glucose: - Is the form of sugar circulating in the blood and is the - Is the form of sugar circulating in the blood and is the

primary fuel to the cells. primary fuel to the cells. - The blood supply comes mainly from the digestion of - The blood supply comes mainly from the digestion of

starch, & sometimes called dextrose.starch, & sometimes called dextrose. - Is a moderately sweet sugar.- Is a moderately sweet sugar.

• Fructose: is found mainly in fruits, consider the sweetest of Fructose: is found mainly in fruits, consider the sweetest of the simple sugars.the simple sugars.

• Galactose: comes mainly from the digestion of milk sugar, Galactose: comes mainly from the digestion of milk sugar, or lactose. or lactose.

Disaccharides Disaccharides • Sucrose: Sucrose: - Is common table sugar, its two sugar units are glucose - Is common table sugar, its two sugar units are glucose

& fructose.& 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 - The two single sugar units that compose maltose are

double glucose molecule.double glucose molecule.

Polysaccharides Polysaccharides • 1) Starch: 1) Starch:

- They are found in grains, legumes, and other - They are found in grains, legumes, and other vegetables, and some fruits.vegetables, and some fruits.

- Breakdown more slowly and supply energy - Breakdown more slowly and supply energy over a longer period of time.over a longer period of time.

- Most important dietary carbohydrate- Most important dietary carbohydrate

- The major food sources of starch include - The major food sources of starch include grains in the form of pasta, crackers, bread, and grains in the form of pasta, crackers, bread, and other baked goods, legumes in the form of other baked goods, legumes in the form of beans, & peas, potatoes, rice, corn, & bulgurbeans, & peas, potatoes, rice, corn, & bulgur..

PolysaccharidesPolysaccharides - Whole grains: is used for food products such - Whole grains: is used for food products such

as flours, breads, or cereals that are as flours, breads, or cereals that are produced from unrefined grain, which is produced from unrefined grain, which is grain that still retains its outer bran layers grain that still retains its outer bran layers and inner germ endosperm and their and inner germ endosperm and their nutrients (i.e. dietary fiber, minerals, & nutrients (i.e. dietary fiber, minerals, & vitamins)vitamins)

- Enriched grains: are refined grain products - Enriched grains: are refined grain products to which key nutrients, usually minerals (i.e. to which key nutrients, usually minerals (i.e. iron), and vitamins (i.e. A, C, D, thiamin, iron), and vitamins (i.e. A, C, D, thiamin, riboflavin, & niacin), have been added.riboflavin, & niacin), have been added.

• 2) Glycogen: found in animal muscle tissue, 2) Glycogen: found in animal muscle tissue, and liverand liver

• 3) Dietary fiber 3) Dietary fiber

Polysaccharides: Dietary fiber Polysaccharides: Dietary fiber • Dietary fiber: in humans there is a lack in the Dietary fiber: in humans there is a lack in the

necessary enzymes to digest dietary fiber, used to necessary enzymes to digest dietary fiber, used to treat gastrointestinal problems.treat gastrointestinal problems.

- Cellulose: helps move the food mass along, stimulates - Cellulose: helps move the food mass along, stimulates normal muscle action in the intestine, and forms feces normal muscle action in the intestine, and forms feces for elimination of waste products, the main sources are for elimination of waste products, the main sources are the stems and leaves of vegetables and the coverings the stems and leaves of vegetables and the coverings of seeds and grains.of seeds and grains.

- Noncellulose polysaccharides: they absorb water and - Noncellulose polysaccharides: they absorb water and swell to a larger bulk, thus slowing the emptying of the swell to a larger bulk, thus slowing the emptying of the food mass from the stomach, and preventing spastic food mass from the stomach, and preventing spastic colon.colon.

- Lignin: is a large compound that forms the woody part - Lignin: is a large compound that forms the woody part of certain plants, it also combines with bile acids and of certain plants, it also combines with bile acids and cholesterol in the human intestine, preventing their cholesterol in the human intestine, preventing their absorptionabsorption

Other sweetenersOther sweeteners• Used as sugar replacersUsed as sugar replacers• 2 types:2 types:1) Nutritive sweeteners: 1) Nutritive sweeteners: - They are sweeteners such sugar alcohols that - They are sweeteners such sugar alcohols that

contribute to total calorie intake.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 - They are absorbed slowly in the small

intestine.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.

Other sweetenersOther sweeteners

2) Nonnutritive sweeteners: 2) Nonnutritive sweeteners:

- Alternative sweeteners.- Alternative sweeteners.

- Are sugar substitutes that do not have - Are sugar substitutes that do not have any caloric value.any caloric value.

- Sweet taste without energy.- Sweet taste without energy.

- Commonly used are aspartame & - Commonly used are aspartame & saccharin.saccharin.

- Sweeter than table sugar.- Sweeter than table sugar.

Functions of carbohydratesFunctions 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 - Individual must eat carbohydrate foods regularly

to meet energy demand (to maintain blood to meet energy demand (to maintain blood glucose level & prevent a breakdown of fat and glucose level & prevent a breakdown of fat and protein in tissue).protein in tissue).

Functions of carbohydratesFunctions of carbohydrates

• 2) Special tissue functions:2) Special tissue functions: - Liver: glycogen reserves in the liver & - Liver: glycogen reserves in the liver &

muscles, protect cells from depressed muscles, protect cells from depressed metabolic function.metabolic function.

- Protein & fat: (1) Carbohydrates - Protein & fat: (1) Carbohydrates protects protein to be used in tissue protects protein to be used in tissue growth & maintenance (2) Prevent rapid growth & maintenance (2) Prevent rapid breakdown of fat & produce ketones breakdown of fat & produce ketones (strong acid), this action called (strong acid), this action called antiketogenic effect. antiketogenic effect.

Functions of carbohydratesFunctions of carbohydrates

• 2) Special tissue functions:2) Special tissue functions:

- Heart: fatty acids are the regular fuel - Heart: fatty acids are the regular fuel for energy, in emergency situation for energy, in emergency situation glycogen.glycogen.

- Central nervous system: the brain need - Central nervous system: the brain need continues supply of glucose, otherwise continues supply of glucose, otherwise low sugar cause brain damage.low sugar cause brain damage.

Food sources of Food sources of carbohydratescarbohydrates• Starches: Starches:

- Such as grain products (corn, bread), & - Such as grain products (corn, bread), & vegetables (tomatoes, onions).vegetables (tomatoes, onions).

- Provide energy for prolong period.- Provide energy for prolong period. - Basic component in the balanced diet.- Basic component in the balanced diet. - Unrefined forms are considered sources of fiber - Unrefined forms are considered sources of fiber

& other nutrients.& other nutrients.

• Sugars:Sugars: - Such as candies, fruits, milk.- Such as candies, fruits, milk. - are necessary for health but in a moderate - are necessary for health but in a moderate

amount.amount. - High sugar diets= risk for dental caries & - High sugar diets= risk for dental caries &

obesity. obesity.

Digestion of carbohydratesDigestion of carbohydrates

• Mouth: digestion by 2 types of actions:Mouth: digestion by 2 types of actions: 1) Mechanical process by mastication: breakdown 1) Mechanical process by mastication: breakdown

food into small particles, & mixed with saliva.food into small particles, & mixed with saliva. 2) Chemical process: specific enzymes such as 2) Chemical process: specific enzymes such as

salivary amylase breaks into smaller usable salivary amylase breaks into smaller usable metabolic products.metabolic products.

Example: amylase breakdown starch into dextrin, Example: amylase breakdown starch into dextrin, and disaccharides.and disaccharides.

- Monosaccharides travel to stomach & small - Monosaccharides travel to stomach & small intestine for absorption without further digestion. intestine for absorption without further digestion.

Digestion of carbohydratesDigestion of carbohydrates

• Stomach:Stomach: - Peristalsis: wavelike contractions of the - Peristalsis: wavelike contractions of the

muscle fiber mixes food particles with muscle fiber mixes food particles with gastric secretions.gastric secretions.

- Hydrochloric acid: stops the action of - Hydrochloric acid: stops the action of salivary amylase.salivary amylase.

- In the lower part of the stomach: the - In the lower part of the stomach: the food mass become thick creamy (chyme)food mass become thick creamy (chyme)

- Emptying chyme to duedenum.- Emptying chyme to duedenum.

Digestion of carbohydratesDigestion of carbohydrates• Small intestine: Small intestine: - peristalsis continue mechanical digestion.- peristalsis continue mechanical digestion. - Pancreatic secretions: enter the duodenum - Pancreatic secretions: enter the duodenum

through the common bile duct.through the common bile duct. Pancreatic amylase: (1) digest starch to maltose, Pancreatic amylase: (1) digest starch to maltose,

(2) reduces maltose to monosaccharides, (3) (2) reduces maltose to monosaccharides, (3) breakdown of disaccharides to monosaccharides.breakdown of disaccharides to monosaccharides.

- Intestinal secretions: enzymes attached to - Intestinal secretions: enzymes attached to “special cells on the microvilli” (bruch border), “special cells on the microvilli” (bruch border), sucrase, lactase, & maltase convert sucrase, lactase, & maltase convert dissaccharides (sucrose, lactose, maltose) into dissaccharides (sucrose, lactose, maltose) into monosaccharides (glucose, galactose, & fructose)monosaccharides (glucose, galactose, & fructose)

- Lactose intolerance: inability to break lactose - Lactose intolerance: inability to break lactose into glucose & galactose (lack of lactase into glucose & galactose (lack of lactase enzyme), symptoms include bloating, gas, enzyme), symptoms include bloating, gas, abdominal pain, & diarrhea. abdominal pain, & diarrhea.

Body needs for carbohydrates Body needs for carbohydrates (CHO)(CHO)

• Dietary reference intake: Dietary reference intake: - 45%-65% of an adult total caloric intake should - 45%-65% of an adult total caloric intake should

come from carbohydrate foods.come from carbohydrate foods. - Means 225-325g of CHO for a 2000kcal/day diet- Means 225-325g of CHO for a 2000kcal/day diet - Recommended fiber: choosing carbohydrates - Recommended fiber: choosing carbohydrates

contain whole grain cereals, legumes, contain whole grain cereals, legumes, vegetables, & fruits.vegetables, & fruits.

- Sugars no more than 25% of total calories.- Sugars no more than 25% of total calories.

• Dietary guidelines for americans:Dietary guidelines for americans: - As in food guide pyramid: grains, fruits, & - As in food guide pyramid: grains, fruits, &

vegetables are the foundation of a healthy diet.vegetables are the foundation of a healthy diet.

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