1. CARBOHYDRATES
Chapter 5

2. Carbohydrates Made of carbon, hydrogen, and oxygen in a 1:2:1 ratio
Primary fuel source for body cells
Divided into two main classes:
Simple sugars
Complex sugars

3. MONOSACCHARIDES

4. GLUCOSE Also called hexose or dextrose
Principle building block of all other carbohydrates
Typically exists in the ring form

5. FRUCTOSE Also called levulose Isomer of glucose
Metabolized into glucose by the liver
Small amounts are converted into glycogen, lactic acid, or fat
Found in fruit, honey, and high fructose corn syrup

6. GALACTOSE Not usually found free in nature in large quantities
Isomer of glucose
Typically found as a subunit of lactose
Converted to glucose by the liver
Used as an immediate energy source or is stored as glycogen

7. Other Monosaccharides
Ribose
Five carbon sugar
Used in the formation of RNA
Very little present in our diet
Deoxyribose
Used in the formation of DNA
Not considered a nutrient of our diet since our bodies can make all that it ever needs.

8. DISACCHARIDES

9. MALTOSE Constructed by a condensation reaction
Composed of two glucose molecules
Possesses an alpha bond
Commonly produced by fermentation reactions called malting
Most maltose digested is the result of starch digestion

10. SUCROSE Constructed by a condensation reaction
Composed of one glucose and one fructose
Possesses an alpha bond
Commonly called table sugar and is found in plants such as sugar cane and maple syrup
Purified to form brown, white, and powdered sugars

11. LACTOSE Constructed by a condensation reaction
Composed of one glucose and one galactose
Possesses a beta bond
Beta bonds are difficult to digest
Primary sugar in milk and milk products

12. OLIGOSACCHARIDES 3-10 monosaccharides: raffinose and stachyose
Found in beans and legumes
Not digested by the body
Metabolized by bacteria in the large intestine
Raffinose=galactose+glucose+fructose
Stachyose=galactose+galactose+
glucose+fructose

13. POLYSACCHARIDES Digestible polysaccharides:
Starch
Amylose
Amylopectin
Glycogen
Non-digestible polysaccharides: fibers
Soluble fiber
Insoluble fiber

14. STARCHES 3000 monosaccharides Contain alpha bonds
Amylose is straight chain
Amylopectin is branched chain
High Glycemic Index

15. GLYCOGEN Storage form of glucose in animals and humans
Structure is similar to amylopectin but with more complex branching
Numerous alpha bonds
Found in liver (400 kcal) and muscles (1400 kcal)

16. Fiber Dietary fiber= fibers found naturally in foods
Functional fibers= fiber added to foods that has shown to provide health benefits
Total fiber= dietary fiber + functional fiber

17. Chemical Composition of Fibers
Contain beta bonds
Insoluble: not fermented
Cellulose
Hemicellulose
Lignin*
Soluble: kcal/g
Gum
Pectin
Mucilage

18. Fibers

19. Carbohydrate Digestion

20. Within the Mouth Saliva contains amylase
Converts polysaccharides, starch, into oligosaccharides, maltose, and glucose
Broken down by hydrolysis reaction

21. Within the Stomach
The acidic environment of the stomach inhibits the action of salivary amylase

22. Within the Small Intestines
Pancreatic amylase
Converts oligosaccharides to disaccharides
Intestinal cells release
Maltase
Lactase
Sucrase

23. CARBOHYDRATE ABSORPTION
Monosaccharide absorption occurs in the duodenum
Glucose and galactose by active absorption
Fructose by facilitated diffusion

24. CARBOHYDRATE ABSORPTION
Portal vein transports absorbed monosaccharides to the liver
Liver can then:
Transform them to glucose
Release them back to the blood stream
Store it as glycogen

25. FUNCTIONS OF CARBOHYDRATES
Supplies energy
Protein sparing
Prevents ketosis
Food sweeteners
Fructose
Sucrose
Glucose
Maltose
Galactose

26. FUNCTIONS OF DIETARY FIBER
Promotes regularity and softer, larger stool
Reduces hemorrhoids and diverticula

27. DIVERTICULOSIS

28. FUNCTIONS OF DIETARY FIBER
Promotes regularity and softer, larger stool
Reduces hemorrhoids and diverticula
Aids weight control
Causes a filling of fullness
Slows glucose absorption
Decrease in colon cancer
Reduces cholesterol absorption
Reduces heart disease

29. RECOMMENDED CARBOHYDRATE INTAKE
RDA is 130 g/day for adults
g of CHO/day to prevent ketosis
Recommended: 45-65% of total kcal
g of CHO/day (primarily from white bread, soda, baked goods)
50% of total kcal
Worldwide the CHO intake is +70%

30. RECOMMENDED FIBER INTAKE
Adequate Intake is 25 g/day for women and 38 g/day for men (14g/1000kacl)
Daily Value= 25g/day for 2000 kcal diet
Average U.S. intake= g/day

31. Sample Menus

32. Sample Menus

33. PROBLEMS WITH HIGH SUGAR INTAKES
Empty calories
Dental caries
Glycemic index=the blood glucose response to a given food compared to a standard
Glycemic load=the amount of Carbohydrate in food times the glycemic index for that food. Related to structure, fiber content, amount of processing, and macronutrient content

34. Effects of Ingesting High Glycemic Load Foods
Stimulates insulin release
Insulin increases blood triglyceride levels
Insulin increases LDL
Insulin increase fat synthesis
Increased risk for CVD
Muscles may become resistant to insulin
Increases risk of developing diabetes
Become hungry quicker

35. PROBLEMS WITH HIGH INTAKES OF DIETARY FIBER
Too much fiber (>60 g/day) will:
Require extra intake of fluids
Bind to some vitamins
Develop phytobezoars
Fill the stomach of a young child quickly

36. Lactose Maldigestion Primary lactose maldigestion
75% of world population
Begins to develop around age 3 to 5 years
Secondary lactose maldigestion
Temporary decrease in lactase production
25% of North American population
Increases with age

37. FOOD SWEETENERS Nutritive sweeteners Alternative sweeteners Sugars
Sugar alcohols
Alternative sweeteners
Saccharin
Aspartame
Neotame
Acesulfame-K
Sucralose

38. Read the Nutrition PerspectivePp