1. Simple sugars, complex carbohydrates, and fiber.
The Carbohydrates
Simple sugars, complex carbohydrates,
and fiber.

2. Carbohydrates Body’s preferred source of energy
Cells of body use the carb. Glucose
Most food sources of carbohydrates are plant sources
Why?
One animal source of carbs

3. Classifying Carbohydrates
Simple Sugars
Monosaccharides
Disaccharides
Complex Carbohydrates
Starch
Glycogen
Cellulose (a form of fiber)

4. Carbohydrate Intake Recommended intake of carbohydrate
45-65 % daily kcal should come from carbohydrates
RDA ~130 g carbohydrate/day
Maximum 25% daily kcal from added sugars
~500 kcal/day
Controversial with nutritionists
WHO recommends a maximum of 10% daily kcal from simple sugars

5. Fiber Intake General recommendations:
25g (women) - 38 g (men) fiber/day
Amount recommended drops after age 50 to:
21 g (women) - 30 g (men) fiber/day
Maximum intake recommended: ~40 g/day
Why is too much not a good thing?

6. Evaluating Your Intake
Intake Goals:*
45-65 % daily kcal from carbohydrate
Select primarily from complex carbohydrates
Make half of the complex carbohydrates whole grains
Limit added sugars
25-38 g fiber/day or 21 – 30 g fiber/day of over 50.
max 40 g/day
*Computer programs may suggest different values

7. Carbohydrates All nutritionally important sugars are hexose sugars
All hexose sugars have the same chemical formula

8. Simple Carboydrates
Monosaccharides – C6H12O6
Glucose
Fructose
Galactose
Glucose, fructose and galactose all have the same chemical composition, but they very different properties!
Why?

9. Glucose

10. Glucose Also called  dextrose
Sugar to which all others are converted after absorption
Occurs in the liver
Cell’s preferred source of energy
Under most conditions the brain requires glucose as an energy source
Natural food sources of glucose are limited.
Honey contains glucose

11. Fructose Also called fruit sugar Sweetest of all the carbohydrates
Sources
Fruits
Honey
Added - High fructose corn-syrup is often used to sweeten foods
Too much fructose can draw water into GI tract and cause GI distress

12. Galactose Not very sweet Not found naturally in many foods
Found in “lactaid” milk

13. Disaccharides
Disaccharides are made by joining two monosaccharides by a chemical bond

14. Disaccharides There are three disaccharides:
Sucrose
Maltose
Lactose
Glucose is a component of each disaccharide.

15. Disaccharides 3 disaccharides Sucrose = glucose--fructose
Maltose = glucose--glucose
Lactose = glucose--galactose
Chemical bond

16. Disaccharides Maltose = glucose-____________ Not in many foods
Made when starch breaks down
Find some in barley
Made during fermentation – alcohol synthesis

17. Disaccharides Maltose digestion occurs in the SI Absorption
Digestion breaks the bond between the glucose molecules.
Requires the presence of the SI enzyme maltase.
maltose  _________ + ___________
Absorption

18. Disaccharide Digestion
maltase

19. Disaccharides Sucrose = glucose-____________ Food sources Table sugar
Made from sugar beets and sugar cane
Fairly sweet
Food sources

20. Disaccharides Sucrose digestion occurs in SI Absorption
Enzyme needed = sucrase
Sucrose  _________ + __________
Absorption

21. Disaccharides Lactose = glucose- ___________ Also called milk sugar
Food Sources
Milk
Ice cream, sherbet
Smaller amounts in cheese and yogurt

22. Disaccharides Lactose digestion in SI Absorption
Enzyme required is lactase
Lactose  glucose + ___________
Absorption

23. Lactose Intolerance Who in class is lactose intolerant?
Populations at greatest risk:
Asian - ~ 80%
African descent - ~ 75%
Hispanic -~ 50%
Native Americans - ~ 80%

24. Lactose Intolerance Some refer to this as lactose maldigestion
Biological cause of lactose intolerance
SI does not make enough (or any) lactase
As a result the lactose is not digested
Undigested lactose cannot be absorbed
Amount of lactase made decreases in many people as they age

25. Symptoms of Lactose Intolerance
Undigested lactose:
Draws water into GI tract
Results in bloating, diarrhea, cramps
Metabolized by bacteria in the colon
Bacteria thrive and make gases and acids
These add to the GI distress

26. Managing Lactose Intolerance
Limit intake of milk products
Includes: milk, ice cream, cottage cheese, sherbet, yogurt with added milk solids
To limit the amount of lactose in GI tract at any time
Ingest milk products with other foods
Spread intake over the day

27. Managing Lactose Intolerance
Many can eat:
Hard cheeses
Cheese making process removes much of lactose
Lactose levels decrease as cheeses age
Yogurt and kefir – fermented milk products
Fermentation process breaks down much of the lactose
Lactase treated milks – Lactaid milk

28. Monosaccharide- Summary
Monosaccharrides are single sugars
All isomers of C6H12O6
Glucose serves as the essential energy source, and is commonly known as blood sugar or dextrose.
Fructose is the sweetest, occurs naturally in honey and fruits, and is added to many foods in the form of high-fructose corn syrup.
Galactose rarely occurs naturally as a single sugar.

29. Disaccharide - Summary
Disaccharides are pairs of monosaccharides, one of which is always glucose
Condensation reactions link monosaccharides together.
Hydrolysis reactions split molecules and commonly occur during digestion.
Maltose consists of two glucose units. It is produced during the germination of seeds and fermentation.
Sucrose is fructose and glucose combined. It is made from sugarcane and sugar beets, and tastes sweet.
Lactose is galactose and glucose combined. It is found in milk and milk products.
© 2008 Thomson - Wadsworth

30. Polysaccharides All polymers of glucose We will consider: Glycogen
Starch
Cellulose

31. Polysaccharides Polysaccharides differ in: Function and sources
# glucose
Type of bonding between glucose
Incidence of branching or coiling

32. Polysaccharides Glycogen Function: animal storage form of glucose
Found, made, and used in:
Liver …….
Muscle cells ….
Stores …..

33. Polysaccharides Structure of glycogen
~ million glucose joined by alpha glycosidic bonds
Highly branched
Branch every 5-6 glucose
Why branching is important
Food sources: none
We make glycogen from extra glucose

34. Starch – Complex Carbohdrate
Function: plant storage form of glucose
All food sources of starch are plant sources
Goal is for the majority of the carbohydrates in your diet to be from starch
Starch rich foods include:

35. Starch Structure of starch
~ 100,000 glucose joined by alpha glycosidic bonds
Two Forms
Branched form - amylopectin
branches every ~20 glucose
Coiled form - amylose

36. Starch
Starch digestion and absorption
Mouth
Stomach SI

37. Polysaccharides Cellulose
Function: structural component of all plant cells
Structure
Many glucose bonded by beta glycosidic bonds
We do not have the enzymes needed to digest beta bonds in cellulose
Long, unbranched chains that coil around each other to form fibers
Very strong

38. Polysaccharides Cellulose One of the polysaccharide fibers
We do not have the enzymes needed to digest the bonds in fibers.

39. Fiber Structural components of plants we cannot digest
Classes of fibers:
Cellulose and hemicellulose
Pectins
Gums and mucilages
Lignins

40. Another way to classify fibers
Soluble fibers – viscous, fermentable by bacteria
Gums, mucilages, pectins, some hemicellulose
Food sources
Fruits
Oat bran, Legumes
Insoluble fibers – nonviscous, not digested by intestinal bacteria
Cellulose and lignins
Wheat bran, corn, rye, most vegetables…

41. Functional Fibers Soluble fibers help lower cholesterol levels How?
Soluble fibers bind/trap bile in the SI
As a result the bile is excreted and not recycled
Bile is made from cholesterol
Therefore, the liver uses cholesterol to make more bile
This lowers cholesterol levels

42. Benefits of fiber in diet
Promotes bowel health
Reduces risk of diverticulitis/osis and appendicitis
Softens stools (keeps you regular)
?? Decreased risk colon cancer
Soluble fiber reduces cholesterol levels

43. Diverticular Disease

44. Benefits of fiber in the diet
Slows gastric emptying time
Aids in weight control – feel full longer
Aids in management of diabetes
Fiber slows the absorption of glucose and reduces spikes in blood glucose levels
Adds in weight control
Fiber adds bulk w.o. kcal

45. Fiber Adding fiber to the diet Food sources: approximate fiber level
Add slowly
Increase water intake
Food sources: approximate fiber level
Whole grain breads and cereals: 1-2g/serving
Higher level in many cereals
Vegetables: 2-3 g/serving
Legumes: 5-8 g/serving
Fruits with skins: 2 g/serving
Dried fruit: 2-3 g/serving

46. © 2008 Thomson - Wadsworth

47. Too much fiber in the diet
Harmful effects of excessive fiber intake
Displaces energy and nutrient-dense foods from the diet
Bulk without nutrients
Abdominal discomfort, bloating, and gas from fermentable fibers
May interfere with nutrient absorption

48. Sugar and Health Many high sugar foods are a source of empty calories
All carbohydrates increase risk of dental caries (cavities)
Longer the sugar/starch is on the teeth the greater the risk

49. Sugar Myths Sugar and: Obesity Heart disease Hyperactivity
Extra/empty calories from sugar are converted to fat and can contribute to obesity
Heart disease
High sugar diets have been shown to alter blood lipid levels
Hyperactivity
Criminal behavior

50. Carbohydrate Digestion in the GI Tract
Copyright 2005 Wadsworth Group, a division of Thomson Learning

51. Alternatives to Sugar
© 2008 Thomson - Wadsworth

52. Artificial Sweeteners
Also called nonnutritive sweeteners
Saccharin
Used primarily in soft drinks and as a tabletop sweetener
Rapidly excreted in the urine
Does not accumulate in the body
Has been removed from list of cancer-causing substances
© 2008 Thomson - Wadsworth

53. Artificial Sweeteners
Aspartame
General purpose sweetener
Warning about phenylalanine for those with PKU
Controversial finding that aspartame may have caused cancer in rats
Excessive intake should be avoided by those with epilepsy
© 2008 Thomson - Wadsworth

54. Artificial Sweeteners
Acesulfame-K (acesulfame potassium)
Research confirms safety
Sucralose
Made from sugar
Passes through digestive tract
Neotame
Most recent on the market
Very sweet
Phenylalanine not an issue
© 2008 Thomson - Wadsworth

55. Artificial Sweeteners
Tagatose
Used for foods and beverages
Provides less kcalories than sugar
High doses can cause flatulence and loose stools.
Alitame and Cyclamate
Pending FDA approval
Approved in other countries
© 2008 Thomson - Wadsworth

56. Stevia – An Herbal Alternative
Lacks research
Classified as a dietary supplement
Not required to have testing and FDA approval
© 2008 Thomson - Wadsworth

57. Sugar Replacers
Also called nutritive sweeteners, sugar alcohols, and polyols
Maltitol, mannitol, sorbitol, xylitol, isomalt, and lactitol
Absorbed more slowly and metabolized differently in the body
Low glycemic response
Side effects include GI discomfort
© 2008 Thomson - Wadsworth

58. © 2008 Thomson - Wadsworth