1. Carbohydrates: Simple Sugars and Complex Chains Chapter 51

2. Carbohydrates all plant food milk carbohydrates are not equal
simple carbohydrates
complex carbohydrates

3. Carbohydrates Sugars, starches, and fibers Major food sources: plants
Produced during photosynthesis
Two main carbohydrate types
Simple and complex
Photo © PhotoDisc 3

4. Simple Carbohydrates sugars monosaccharides – single sugars
disaccharides – 2 monosaccharides

5. Simple Sugars: Monosaccharides and Disaccharides
Simple carbohydrates
Monosaccharides
Glucose
Fructose
Galactose
Disaccharides
Sucrose
Lactose
Maltose 5

6. Simple Carbs monosaccharides all are 6 carbon hexes
6 carbons
12 hydrogens
6 oxygens
arrangement differs
accounts for varying sweetness
glucose, fructose, galactose

7. Monosaccharides Glucose Is most abundant Also is called dextrose
Gives food sweet flavor
Provides energy to body cells
Blood sugar
Found in fruits, vegetables, honey
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8. Monosaccharides Fructose Also called levulose or fruit sugar
Tastes the sweetest
Occurs naturally in fruits and vegetables
Found in fruits, honey, and corn syrup
© Photodisc 8

9. Monosaccharides Galactose Primary sugar in milk and dairy products
Rarely found naturally
As a single sugar
- Hardly even taste sweet
© AbleStock 9

10. Disaccharides: The Double Sugars
Two monosaccharides linked
together
Sucrose, lactose, and maltose 10

11. Disaccharides pairs of the monosaccharides glucose is always present
2nd of the pair could be fructose, galactose or another glucose
taken apart by hydrolysis
put together by condensation
hydrolysis and condensation occur with all energy nutrients
maltose, sucrose, lactose

12. Condensation making a disaccharide
chemical reaction linking 2 monosaccharides

13. Hydrolysis breaking a disaccharide water molecule splits
occurs during digestion

14. Disaccharides: The Double Sugars
Sucrose: glucose + fructose
“Table sugar”
Made from sugar cane and sugar beets
Listed as “sugar” on food labels
Lactose: glucose + galactose
“Milk sugar”
Found in milk and milk products 14

15. Sucrose fructose and glucose tastes sweet
fruit, vegetables, grains
table sugar is refined sugarcane and sugar beets
brown, white, powdered

16. Lactose glucose and galactose main carbohydrate in milk
known as milk sugar

17. Lactose Intolerance age, damage, medication, diarrhea, malnutrition
management requires dietary change
6 grams (1/2 cup) usually tolerable
take in gradually
hard cheeses & cottage cheese
enzyme drops or tablets
lactose free diet is extremely difficult to accomplish

19. Disaccharides: The Double Sugars
Maltose: glucose + glucose
Product of starch breakdown
Found in germinating cereal grains
Not abundant

20. Complex Carbohydrates
starches and fibers
polysaccharides
chains of monosaccharides

21. Complex Carbohydrates
Chains of two or more sugar molecules
Oligosaccharides
Polysaccharides
Structural differences
Digestible or nondigestable 21

22. Complex Carbohydrates
Starch
How plants store energy
Found in grains, legumes, and tubers
Long chains of glucose units
Amylose—straight chains
Amylopectin—branched chains
Resistant starch 22

23. Starches
stored in plant cells
body hydrolyzes plant starch to glucose

24. Complex Carbohydrates
Glycogen
Body’s storage form of carbohydrate
Provides glucose when blood glucose levels get low
Highly branched chains of
glucose units
Most stored in our skeletal
muscle and liver
Carbohydrate “loading” 24

25. Glycogen limited in meat and not found in plants BUT
not an important dietary source of carbohydrate
BUT
all glucose is stored as glycogen
long chains allow for
hydrolysis and release
of energy

26. Complex Carbohydrates
Fiber
Indigestible chains of monosaccharides
Dietary fiber: found in plants
Fruits, vegetables, legumes, and whole grains
Functional fiber: isolated and added to foods 26

27. Fiber structural parts of plants
found in all plant derived food
bonds of fibers cannot be broken down during the digestive process
minimal or no energy available

28. Complex Carbohydrates
Types of fiber
Oligosaccharides: short chains of monosaccharides
Raffinose, stachyose
Dried beans, peas,
lentils, human milk
Cellulose
In plants: grains, fruit,
nuts, vegetables
Hemicellulose
Variety of monosaccharides 28

29. Complex Carbohydrates
Pectins
All plants, especially fruits
Gums and cilages
Gel-forming fibers that hold plant cells together
Lignins
Nondigestable substances in vegetables and fruit 29

30. Fiber types pectins lignins resistant starches cellulose
classified as fibers
escape digestion and absorption

31. Fiber Characteristics
soluble fibers, viscous, fermentable
easily digested by bacteria in colon
associated with protection against heart disease and diabetes
lower cholesterol and glucose levels
found in legumes and fruits

32. Fiber insoluble and not easily fermented promote bowel movements
alleviate constipation
found in grains and vegetables

34. Carbohydrate Digestion
break down into glucose
body is able to absorb and use
large starch molecules
extensive breakdown
disaccharides
broken once
monosaccharides
don’t need to be broken down

35. Carbohydrate Digestion and Absorption
Digestion: breaking down carbohydrates into simple sugars
Begins in the Mouth – Chewing releases saliva
Salivary amylase begins digestion of carbohydrates
Stomach
No carbohydrate digestion 35

36. Carbohydrate Digestion and Absorption
Small intestine
Pancreatic amylase continues starch digestion
The brush border enzymes digest disaccharides
Other digestive enzymes
Maltose, sucrose, and lactase 36

37. small intestine majority of carbohydrate digestion takes place here
pancreatic amylase reduces carbs to glucose chains or disaccharides
specific enzymes finish the job
maltase
maltose into 2 glucose
sucrase
sucrose into glucose and fructose
lactase
lactose into glucose and galactose

38. large intestine 1-4 hours for sugars and starches to be digested
only fibers remain
attract water, which softens stool
bacteria ferment some fibers
water, gas, short-chain fatty acids (used for energy)

39. Carbohydrate Digestion and Absorption
Absorption: The small intestine swings into action
End products of carbohydrate digestion
Glucose
Galactose  glucose
Fructose  glucose
Liver stores and releases glucose
To maintain blood glucose levels 39

40. Carbohydrate Digestion and Absorption
Travels with carbohydrate 40

41. Carbohydrates
glucose provides energy for the brain and ½ of energy for muscles and tissues
glycogen is stored glucose
glucose is immediate energy
glycogen is reserve energy

42. Carbohydrates in Action
Glucose is our primary fuel
Maintain normal blood glucose levels
Excess glucose is stored
Using glucose for energy
Stored glucose as glycogen
Liver
Muscle 42

43. Carbohydrate Metabolism
1/3 of body’s glycogen is stored in liver
released as glucose to bloodstream
eat – intake glucose
liver condenses extra glucose to glycogen
blood glucose falls
liver hydrolyzes glycogen to glucose
Glycogen is bulky, so we store only so much: short term energy supply
Fat is the long term energy supply.

44. Glucose for Energy enzymes break apart glucose – yielding energy
inadequate supply of carbohydrates
ketone bodies (fat fragments) are an alternate energy source during starvation
excess ketones can lead to ketosis: imbalance of acids in body
minimum of 50 – 100 grams of carbs/day are needed to avoid ketosis

45. Carbohydrates in Action
Using glucose for energy
Sparing body protein
Adequate carbohydrates spare protein
Preventing ketosis
Ketone bodies
Ketosis  dehydration

46. Glucose Homeostasis
maintaining an even balance of glucose is controlled by insulin and glucagon
insulin
moves glucose into the blood
glucagon
brings glucose out of storage

47. Carbohydrates in Action
Regulating blood glucose
Why? To maintain supply for cells
Controlled by hormones
Insulin
Key
Glucagon
Breaks down glycogen
Epinephrine
“Fight or flight” hormone
Glycemic index 47

48. Maintaining Blood Glucose Homeostasis1
Intestine
Maintaining Blood Glucose Homeostasis
When a person eats,
blood glucose rises. 2
Pancreas
High blood glucose stimulates
the pancreas to release insulin.
Insulin 3
Insulin stimulates the uptake of
glucose into cells and storage
as glycogen in the liver and
muscles. Insulin also stimulates
the conversion of excess
glucose into fat for storage.
Liver
Fat cell
Muscle 4
As the body's cells use
glucose, blood levels decline. 5
Pancreas
Low blood glucose stimulates
the pancreas to release
glucagon into the bloodstream.
Glucagon 6
Glucagon stimulates liver
cells to break down glycogen
and release glucose into the
blood.a
Glucose
Insulin
Glucagon
Glycogen
Liver
a The stress hormone
epinephrine and other hormones
also bring glucose out of storage. 7
Blood glucose begins to
rise.

49. Carbohydrates in Action: Regulating Blood Glucose49

50. Carbohydrates in Action
Diabetes mellitus
Consequences
Hyperglycemia—persistent high blood glucose levels
Glucose unable to enter cells
Increased risk of high blood pressure, heart disease, and kidney disease
Damage to body proteins and tissues 50

51. Carbohydrates in Action
Diabetes mellitus
Type 1 diabetes: lack of insulin production
Type 2 diabetes: cells are resistant to insulin
Prediabetes
Insulin resistance
Gestational diabetes: occurs during pregnancy 51

52. Carbohydrates in Action52

53. Carbohydrates in Action
Diabetes
Best prevention
Healthful diet
Monitoring and well-balanced meals
The Exchange List for Meal Planning
Regular exercise 53

54. Sugar ½ comes from natural sources, ½ from refined and added
sucrose, corn syrup, honey
excess can lead to nutrient deficiencies and tooth decay
empty calories
sugar and starch break down in the mouth

55. Sugar recommended intake
added sugar = no more than 10% of energy intake

56. Carbohydrates in Action
Low blood glucose: hypoglycemia
Symptoms
Nervousness, irritability, hunger, headache, shakiness, rapid heart rate, and weakness
Results from
Too much insulin, missed meals, and vigorous exercise
Reactive hypoglycemia
Fasting hypoglycemia 56

57. Carbohydrates in Your Diet
Recommended carbohydrate intake
RDA = 130 grams per day
AMDR = 45–65% of calories
Daily Value (for 2,000 kcal) = 300 grams
Dietary Guidelines
Choose carbohydrates wisely
Choose fiber-rich fruits, vegetables, and whole grains often 57

58. Carbohydrates in Your Diet
Choosing carbohydrates wisely
Increase fruit, vegetables, whole grains, low-fat milk
Strategies
Eat peel of fruit/vegetables
Eat legumes
Choose brown rice
Choose high-fiber cereal
Gradually increase and drink plenty of water! 58

59. Starch and Fiber diet that includes starch, fiber and natural sugars
whole grains, vegetables, legumes, fruits
may protect against heart disease and stroke
reduces the risk of type 2 diabetes
enhances the health of the large intestine
can promote weight loss

60. Carbohydrates in Your Diet
Moderating sugar intake
Use less added sugar
Limit soft drinks, sugary cereals, and candy
Choose fresh fruits or those canned in water or juice
Photo © CSquared Studios/PhotoDisc 60

61. Carbohydrates in Your Diet
Nutritive sweeteners
Natural vs. refined
Sugar alcohols
Non-nutritive sweeteners
Saccharin
Aspartame
Acesulfame K
Sucralose 61

62. Artificial Sweeteners
help keep sugar and energy intake down
anything we eat has FDA approval
saccharin
aspartame
acesulfame potassium
sucralose
neotame

64. Carbohydrates and Health
Sugar
High sugar intake may be low in nutrients
High sugar intake promotes tooth decay
PhotoDisc 64

65. Sugar Replacers sugar alcohols provide bulk and sweetness
cookies, gum, candy, jelly
do contain minimal kcal
low glycemic response
absorbed slowly
do not cause dental caries

66. Carbohydrates and Health
Fiber
Possible role in weight control
Better control of blood glucose
Reduced risk of heart disease
Healthier gastrointestinal functioning
Negative effects of excess fiber
Gradual intake and increased water consumption
Can bind small amounts of minerals 66