Download Chapter 4 Carbohydrates Chapter Outline I. What Are

Chapter 4
Carbohydrates
Chapter Outline
I. What Are Carbohydrates? *Carbohydrates include the simple sugars and complex
carbohydrates.
II. Simple Sugars: Monosaccharides and Disaccharides
A. Monosaccharides: the single sugars (Figure 4.3). *Monosaccharides are the building
blocks of carbohydrates. Three monosaccharides are important in human nutrition:
glucose, fructose, and galactose.
1. Glucose
2. Fructose
3. Galactose
B. Other monosaccharides and derivative sweeteners
C. Disaccharides: the double sugars (Figure 4.4). *The monosaccharides combine to
make disaccharides: sucrose, lactose, and maltose.
1. Joining and cleaving sugar molecules (Figures 4.6 and 4.7)
2. Sucrose
3. Lactose
4. Maltose
Key terms: simple carbohydrates, monosaccharides, disaccharides, glucose, fructose, galactose,
pentose, sugar alcohols, condensation, hydrolysis, sucrose, lactose, maltose
III. Complex Carbohydrates
A. Oligosaccharides
B. Polysaccharides. *Starch, glycogen, and fiber are long chains (polysaccharides) of
glucose units.
1. Starch
2. Glycogen
3. Fiber (Table 4.1)
a. Cellulose
b. Hemicelluloses
c. Pectins
d. Gums and mucilages
e. Lignins
f. b-glucans
g. Chitin and chitosan
Key terms: complex carbohydrates, oligosaccharide, polysaccharide, starch, amylose,
amylopectin, resistant starch, glycogen, dietary fiber, cellulose, hemicellulose, pectin, gum,
mucilage, psyllium, lignin, b-glucans, chitin, chitosan, total fiber
IV. Carbohydrate Digestion and Absorption. *Carbohydrates are digested by enzymes from the
mouth, pancreas, and small intestine and are absorbed as monosaccharides.
A. Digestion (Figure 4.11)
B. Absorption (Figure 4.13). *The liver converts the monosaccharides fructose and galactose to
glucose.
Key terms: pancreatic amylase, alpha bond, beta bond
V. Carbohydrates in the Body
A. Normal use of glucose. The main function of carbohydrates in the body is to supply
energy. In this role, carbohydrates spare protein for use in making body proteins, and
allow for the complete breakdown of fat as an additional energy source.
1. Using glucose for energy
2. Storing glucose as glycogen
3. Sparing body protein
4. Preventing ketosis
B. Regulating blood glucose levels (Figure 4.14). *Blood glucose levels rise after eating
and fall between meals. Two pancreatic hormones, insulin and glucagon, regulate blood
glucose levels, preventing extremely high or low levels.
C. Inadequate Regulation of Blood Glucose Levels: Diabetes Mellitus * A chronic
disease in which uptake of blood glucose by body cells in impaired, resulting in high
glucose levels in the blood and urine.
Key terms: ketone bodies, ketosis, blood glucose level, insulin, glucagon, epinephrine, glycemic
index, diabetes mellitus,
VI. Carbohydrates in the Diet. *Carbohydrates are found mainly in plant foods as starch, fiber,
and sugar.
A. Recommendations for carbohydrate intake
B. Current consumption: In general, Americans consume more sugar and less starch and
fiber than is recommended
C. Choosing carbohydrates wisely
1. Strategies for increasing fiber intake
D. Moderating sugar intake
1. Nutritive sweeteners
a. Natural sweeteners
b. Refined sweeteners
c. Sugar alcohols
2. Non-nutritive sweeteners
a. Saccharin
b. Aspartame
c. Acesulfame K
d. Sucralose
3. Other sweeteners
Key terms: germ, endosperm, bran, husk, nutritive sweetener, refined sweeteners, nonnutritive
sweetener, saccharin, aspartame, phenylketonuria (PKU), acesulfame K, sucralose, alitame, dtagatose, trehalose, neotame, stevioside, stevia, dihydrochalcones (DHCs), polyols, thaumatin
VII. Carbohydrates and Health. *Carbohydrate intake can affect health. Excess sugar can
contribute to low nutrient intake, excess energy intake, and dental caries.
A. Sugar and dental caries
B. Fiber and obesity
C. Fiber and type 2 diabetes
D. Fiber and cardiovascular disease
E. Fiber and gastrointestinal disorders
F. Negative health effects of excess dietary fiber