1. Williams' Basic Nutrition & Diet Therapy
Chapter 2
Carbohydrates
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2. Nature of Carbohydrate
Nutrients-have 3 essential elements
Provide energy to do its work
Provide building materials to maintain it form and functions
Control agents to regulate these processes efficiently
Plentiful in food supply
Important in well balanced diet
Have 4 kcal/g so a food has 40 g of CHO then they will consume 160 kcal.
Share these facts with the students:
In the typical American diet, half of total caloric intake is in the form of carbohydrates.
Daily intake of sugars by Americans accounts for 20% to 40% of total caloric intake.
Ask the students what some of the major sources of sugars are in their own diets.

3. Nature of Carbohydrates
Relation to Energy
Basic fuel source
Human body can break down carbohydrates rapidly
Provide energy
Energy production system
Change basic fuel to refined fuel to use
Transport refined fuel to places need
Burn refined fuel in places taken
Dietary importance
Widely available
Low in cost
Store easily
Share these facts with the students:
In the typical American diet, half of total caloric intake is in the form of carbohydrates.
Daily intake of sugars by Americans accounts for 20% to 40% of total caloric intake.
Ask the students what some of the major sources of sugars are in their own diets.

4. Classes of Carbohydrates
Composed of carbon, hydrogen, and oxygen
Saccharide
Classified by number of sugars that make it up
Simple carbohydrates
Monosaccharides
disaccharides
Complex carbohydrates
polysaccharides
Which simple carbohydrate is the basic sugar unit in human blood? (Glucose)
In which food group is fructose most abundantly found? Explain that fructose is also concentrated from corn to make high-fructose corn syrup, a sweetener added to many beverages and sweets in the American diet.
Explain that galactose is usually found in conjunction with glucose, to make lactose, a milk sugar.

5. Classes of Carbohydrates
Monosaccharides
Glucose: basic single sugar in human metabolism-converted in the body; major fuel for body cells
Fructose: primarily found in fruits and honey; the riper the fruit the higher the fructose
Galactose: product of lactose digestion
Which simple carbohydrate is the basic sugar unit in human blood? (Glucose)
In which food group is fructose most abundantly found? Explain that fructose is also concentrated from corn to make high-fructose corn syrup, a sweetener added to many beverages and sweets in the American diet.
Explain that galactose is usually found in conjunction with glucose, to make lactose, a milk sugar.
Copyright © 2013 Mosby, Inc., an imprint of Elsevier Inc. All rights reserved.

6. Classes of Carbohydrates
Disaccharides
Sucrose: common table sugar
Lactose: sugar found in milk; contains the least amount of carbohydrate content; yielding galactose and glucose
Maltose: found in molassess; product of intermediate breakdown of starch by the body
Carbohydrates are more concentrated in dried fruits, juices, and starchy vegetables
Which disaccharide aids in the absorption of calcium and phosphorous? (Prompt the students to think of a food that is high in these minerals and also high in lactose: milk.)
Explain that maltose can be found naturally in foods such as beer but that most often it is an intermediate disaccharide that results from the digestion of starch.
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7. Classes of Carbohydrates
Polysaccharides
Complex carbohydrates
Composed of many single-sugar units
Starch: most significant polysaccharides
Found in grains, legumes, and other vegetables and some fruits
Glycogen: formed within body tissues; crucial; composed of hundreds of units of glucose
Dietary fiber: important dietary assets
Explain that plants form glucose into starch and animals form glucose into glycogen.
Ask the students to name sources of starch. (Grains, legumes, potatoes)
Draw structures of starch and glycogen on a whiteboard or chalkboard. Explain the difference between the two, noting that glycogen can be broken down from many different end points at the same time because of its branching, whereas starch can only be broken down on either end. This makes glycogen a better storage form of glucose for human beings because it responds more quickly when blood glucose levels are down.
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8. Dietary Fiber
Whole grains-flours, breads, or cereals from unrefined grain-retaining the outer bran layer, inner germ, and endosperm
Legumes-beans, peas, lentils
Vegetables
Fruits with as much skin remaining as possible
Discuss the dietary role of each of the polysaccharides.

9. Dietary Fiber Health organizations emphasize role of dietary fiber
Recommended daily intake for men age 50 and younger: 38 g/day
For women: 25 g/day
Increases should be gradual
Ask students to suggest some of the reasons most Americans do not consume sufficient dietary fiber.
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10. Cellulose Cellulose: chief component of cell walls in plants Lignin
Only noncarbohydrate dietary fiber
Large compound, forms woody part of some plants
Noncellulose polysaccharides-pectins and other polysaccharides
Absorb water and swell to larger size, slowing stomach emptying
Bind with bile acids
Provide bulk for normal muscle action
Discuss with the students how they could incorporate more cellulose-rich foods into their diets.

11. Other Sweeteners Alternative Sweeteners-replacing sugar
Nutritive sweeteners
Sugar alcohols (sorbitol, mannitol, xylitol)
Contribute to total calorie intake
Down side is slow digestion and can cause osmotic diarrhea
Nonnutritive sweeteners
Artificial sweeteners in food
Have no caloric value
Nonnutritive sweeteners are hundreds of times sweeter than table sugar. Explain how adding a minute amount can sweeten a food.

12. Functions of Carbohydrates
Primary energy function
Basic fuel supply
Physical activities
Work of body cells
Reserve fuel supply
Liver stores about 100 g of glycogen
Muscle stores g
Maintains blood glucose level
TALKING POINTS:
Carbohydrates burn in the body at a rate of 4 kcal/g. Explain this in terms of work: 30 minutes jogging burns approximately 200 calories. How many grams of carbohydrate would be needed to provide that energy? (50 g)
How many pieces of bread would a person need to eat to get 50 g? (3 to 4 pieces)
Explain the process of blood glucose level variance and homeostasis. The body regulates blood glucose to keep all cells provided with energy at all times.
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13. Other Sweeteners
Nutritive sweeteners: Absorb more slowly and increase blood sugar more slowly than glucose
Nonnutritive sweeteners: Several hundred times sweeter than sucrose (table sugar)
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14. Functions of Carbohydrates
Primary energy function (cont’d)
Special tissue functions
Liver: Glycogen reserves maintain overall energy balance; major organ for metabolic processing of carbohydrates
Carbohydrate protects protein and fat supply and will keep fat from breaking down which can lead up to a build of ketones
Central nervous system depends on constant carbohydrate supply
The protein-sparing function of carbohydrates protects proteins, allowing them to be used for tissue growth and maintenance.
Carbohydrates prevent the rapid breakdown of fats that would produce excess amounts of ketones.
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15. Food Sources of Carbohydrates
Remember proteins such as meat do not contain carbohydrates
Starches
Most important carbohydrate in the diet
Whole-grain starches such as rice, wheat, corn, potatoes
Sugars
Not necessarily bad
Added sugars provide empty calories
Moderation is key
Explain that one of the easiest steps someone dieting can take is to cut sugared drinks from the diet.

16. Digestion of Carbohydrates
Mouth
Mechanical or muscle functions break food mass into smaller particles by a process called mastication
Chemical process in which enzymes begin breaking food down
Stomach
Peristalsis continues mechanical breakdown
Gastric secretions continue chemical breakdown of nutrients
Secretions do not break down carbohydrates but stop action of salivary amylase
Explain how amylases are named according to where they are found: in the mouth (salivary) and in the small intestine (pancreatic)
In which part of the digestive process do proteases start digesting proteins? (Stomach)
Is peristalsis a voluntary or involuntary movement? (Involuntary)

17. Digestion of Carbohydrates
Small intestine
Peristalsis continues mechanical breakdown of food
Enzymes from pancreas and intestine continue chemical breakdown
glucose, galactose, and fructose—ready for absorption directly into the portal blood circulation in the liver
Pancreatic secretions: pancreatic amylase breaks starches down into disaccharides and monosaccharides.
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18. Digestion of Carbohydrates
Pancreatic secretions
Enter duodenum through common bile duct
Contain pancreatic amylase to continue breakdown of starch
Intestinal secretions
Three disaccharidases: sucrose, lactase, maltase
Render disaccharides into monosaccharides
Intestinal secretions: sucrase, lactase, and maltase act on disaccharides to render their corresponding monosaccharides ready for portal absorption.
Which section of the small intestine performs most of the absorption of macronutrients? (Duodenum)
Ask students to explain the cause of lactose intolerance.
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19. Recommendations for Dietary Carbohydrate
Dietary Reference Intakes
45% to 65% of adult’s total caloric intake should come from carbohydrate foods
Limit sugar to no more than 25% of calories consumed
Dietary Guidelines for Americans, 2010
Does not provide a specific caloric number or percentage, but does provide recommendations
What recommendations do the Dietary Guidelines for Americans, 2010 make?
What recommendations would the students provide to others?
Copyright © 2013 Mosby, Inc., an imprint of Elsevier Inc. All rights reserved.