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8/13/2019 Nutrition Lecture 8
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Carbohydrates have many functions
1. Primary source of energy, especially for our brain andnervous system
2. Spares protein from being wasted
3. Maintains normal balance of water and sodium
4. Precursor compound for many body tissues5. Helps in absorption of some nutrients
6. Needed for fat metabolism
7. Helps Central Nervous System function
8. Effects the growth of goodbacteria
9. Provides fiber/bulk
10. Adds flavor, color, and texture to the diet
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Carbohydrates in FoodsCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
MyPlate:
Sources of Carbohydrates
Grains Vegetables Fruits Dairy Protein
15 grams per
serving
5 grams per
serving18 grams per
serving
Milk
Yogurt
Beans
Nuts
12 grams per
serving
4-10 grams per
serving
ChooseMyplate.gov
All varieties All varieties All varieties
(grains): Keith Weller/USDA; (vegetables): Mitch Hrdlicka/Getty Images RF; (fruits): Ingram Publishing/SuperStock RF
Grains
Fruits
ProteinVegetables
Dairy
Grains
Fruits
ProteinVegetables
Dairy
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Top 5 sources of CHO in American
diet??
White bread
Soft drinks
Cookies and cakes (and doughnuts)
Sugars/syrups/jams
Potatoes
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Photosynthesis
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Carbohydrates = CHO
Classified as simple or complex
Made up of 3 elements:
Carbon
Hydrogen
Oxygen
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Monosaccharides = Simple CHO
Glucose Fructose
Galactose
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Glucose
Major monosaccharide in the body
Also known as dextrose
In bloodstream called blood sugar
Breakdown of starches and sucrose
Source of fuel for cells
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Fructose (fruit sugar)
In fruit, honey, and high-fructose corn syrup
Converted into glucose in the liver
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Galactose
Does not occur in foods to any significant extent
Primarily is found in food as part of the disaccharide
lactose
Converted to glucose in the liver
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Disaccharides: Simple CHO
Sucrose (Gluc + Fruc)
Table sugar
Lactose (Galactose + Gluc)
Milk products
Maltose (Gluc + Gluc) Fermentation
Alcohol production
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Complex Carbohydrates
Oligosaccharides
Starch: Amylose, Amylopectin
Glycogen
Dietary fiber
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Oligosaccharides
3 to 10 monosaccharides
Cannot be digested
Chicory root, inulin
Occur naturally in some foods
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Polysaccharides
Starch= glucose units linked in long, occasionally branchedchains. Human digestive enzymes can digest these bonds,retrieving glucose.
Glycogen= bonds between glucose units, like those of starch,can be broken by human enzymes, but the chains are morehighly branched.
Dietary fiber = bonds that link glucose units together aredifferent from those of starch and glycogen. Human enzymescannot digest them.
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Common Starches
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Glycogen
Storage form of carbohydrate for animals andhumans
Structure similar to amylopectin Stored in the liver and skeletal muscles
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Dietary Fiber
Indigestible CHO
Body cannot break the bonds
Insoluble fiber Cellulose, hemicellulose, lignin
Not fermented by the bacteria in the colon
Soluble fiber
Gum, pectin, mucilage Fruit, vegetable, rice bran, psyllium seed
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Soluble and Insoluble Fiber
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Benefits of Dietary Fiber
S
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Sweeteners
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High-fructose Corn Syrup
55% fructose
Cornstarch mixed with acid and enzymes
Starch is broken down to glucose
Some glucose is converted to fructose
Cheaper than sucrose
Does not form crystals
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Other Types of Sweeteners
Brown sugar
Turbinado sugar (raw sugar)
Maple syrup
Honey
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Sugar Substitutes
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Saccharin (Sweet & Low)
First produced in 1879
180-200x sweeter than sucrose
No potential risk in humans
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Sugar Alcohols
Sorbitol, Xylitol
~2.6 kcals/gram
Large quantities can cause diarrhea
Do not promote tooth decay
Xylitol can actually inhibit bacteria that cause oral
caries (cavities)
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Gums
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Aspartame (Equal, NutraSweet)
Composed of phenylalanine, aspartic acid, andmethanol
180-200x sweeter than sucrose
4 kcal/gm
Not heat stable Complaints of sensitivity
Headaches, dizziness, seizures, nausea, etc.
Acceptable daily intake: 50 mg per kg body weight (FDA)
(~14 cans of diet soda for average adult per day) Warning label for Phenylketonuria (PKU)
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Sucralose (Splenda)
600x sweeter than sucrose
Substitutes chlorines for hydroxyl groups on sucrose
Heat stable
Tiny amount digested
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Stevia (Truvia)
Stevia is a plant (specifically, a member of the
chrysanthemum family) native to portions of
northeastern Paraguay. It has been used to sweeten
foods and beverages for more than 200 years. Initially NOT approved by FDA as an additive
Heat stable, 300 times sweeter than sugar
Made from rebiana, the best tasting part of the
stevia leaf, erythritol and natural flavors
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Acceptable Daily Intakes (ADI)
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Real Sugar?
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Carbohydrate Digestion
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Effects of Cooking
Softens fibrous tissues
Easier to chew and swallow
f b h d h
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Digestion of Carbohydrate in the
Mouth
Salivary amylase
Breaks starch to shorter saccharides
Prolonged chewing
Short duration in the mouth
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Digestion of Carbohydrate in the Stomach
Acidic environment
No further starch digestion
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Digestion of Carbohydrate in the Small
Intestine
Pancreas releases enzymes
Pancreatic amylase
Cells in the small intestine release Maltase
Sucrase
Lactase
Monosaccharides are absorbed
Carbohydrate Digestion
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Carbohydrate Digestion
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Lactose Maldigestion
Reduction in lactase (enzyme that digests lactose)
Lactose is undigested and not absorbed
Lactose is metabolized by large intestinal bacteria
Causes gas, bloating, cramping, discomfort
Primary lactose maldigestion
Secondary lactose maldigestion
Severe cases are called lactose intolerance
What To Do if You Have Lactose
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What To Do if You Have Lactose
Maldigestion or Lactose
Intolerance
Determine amount you can tolerate
Eat dairy with fat
Cheese & yogurt are usually well tolerated
Use lactase-treated milk or take enzyme pills before
dairy
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After Absorption
Monosaccharides are transpoted to the liver via the
portal vein
Liver can:
Transform monosaccharides into glucose
Release glucose back into the bloodstream
Store as glycogen (or fat)
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Undigested Carbohydrates
Only a minor amount escapes digestion
Travels to the colon
Fermentation by the bacteria
Acids and gases produced are absorbed
May promote health of the colon
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Functions of Carbohydrate
Supplies energy
Adds sweetness to foods
Spares protein
Prevents ketosis
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Protein-sparing action of CHO
Allows protein to be used in the body as intended Ketones= intermediate products from fat oxidation
Water loss (dehydration)
Sodium imbalance
Stress on the kidneys
Nausea
Decreased appetite
Fatigue
Ketosis= a condition when an undesirably high concentration of
ketone bodies, such as acetone, is in the blood or urine. This
disturbs normal acid-base balance and leads to other health
problems.
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Blood Glucose Control
Role of the liver
Regulates glucose that enters bloodstream
Role of the pancreas
Release of insulin
Release of glucagon
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Functions of Insulin
Promotes glycogen synthesis
Increases glucose uptake by the cells
Reduces gluconeogenesis
Net effect: lowers blood glucose
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Functions of Glucagon
Breakdown glycogen
Enhances gluconeogenesis
Net effect: raises blood glucose
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Epinephrine / Norepinephrine
Fight or flightresponse
Breakdown glycogen Raises blood glucose
Regulation of Blood Glucose
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Regulation of Blood Glucose
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Glycemic Response
Glycemic Index
Ratio of blood glucose response to a given food
Glycemic Load
Grams of carbohydrate in a food multiplied by theglycemic index of that food
Divide result by 100
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Dietary Fiber and Health
Diverticulosis/Diverticulitis
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Diverticulosis/Diverticulitis
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Weight Control and Soluble Fiber
Slows down gastric emptying time
Low in kcal
Satisfied after eating
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Colon Cancer and Fiber
Conflicting research study results
Focus on fruits, vegetables, beans, and wholegrains
Higher-fiber foods are more nutrient dense
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Glucose Absorption and Fiber
Soluble fiber slows glucose absorption
Better blood glucose regulation
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Carbohydrate Needs
RDA is 130 grams/day for adults
Average U.S. intake is 180-330 grams
Recommendations vary
FNB: 45%-65% of total calories
Nutrition Facts panel: 60%
Focus on fruits, vegetables, whole grains
Recommendations for Complex
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Recommendations for Complex
Carbohydrates
Daily Value
300 grams of complex carbohydrate or 60% of totalcalories
Healthy People 2020
Increase the contribution of whole grains to the diets ofthe population aged 2 years and older
World Health Organization (WHO)
Lower limit: 50% of total calories from complex
carbohydrates Upper limit: 75% of total calories from complex
carbohydrates
W il t th 130 f CHO d
http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=29http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=29http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=29http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=29http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=29http://www.healthypeople.gov/2020/topicsobjectives2020/objectiveslist.aspx?topicId=298/13/2019 Nutrition Lecture 8
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We can easily get the 130 grams of CHO per day
from:
1 cup of cereal = 30 grams
2 slices of bread = 30 grams
1.5 cups of fruit = 45 grams
1.5 cup of milk = 18 grams
1 cup vegetables = 10 grams
TOTAL = 133 grams
1 tsp. of sugar = 4 grams
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Too Much Fiber
> 60 grams/day
Extra fluid needed
May decrease availability of some minerals
Recommendations for Simple Sugar
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Recommendations for Simple Sugar
Intake
Low nutrient density
Dental caries
Added to food and beverages
< 10% of total kcal/day with a maximum of 50 grams
(12 tsp) per day--WHO
Average U.S. intake: 16% of total kcal/day
~82 grams per day
How to control simple carbohydrates
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p y
in your own diet
Decrease your sweets (cut down the soft drinks, increase water and milk) Avoid presweetened items (i.e. cereals)
Add your own sugar, so that you can control the amounts -Every teaspoonfulof sugar gives us 16 calories and 4 grams of CHO
Learn to like a less sweet tastewean yourself off sugar
Combine sweet foods with more nutritious ones. Avoid the "caffeine & calories" breaks. Have cereal, toast, milk, juice instead
(or go for a "walk break").
Read labels. Look for sugar, sucrose, fructose, corn syrup, honey, molasses,etc.
Watch out for low fat productssugar is often used to make the producttaste good
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EXAMPLES OF WHOLE GRAINS
WHOLE GRAIN WHOLE WHEATWhole-wheat bread
Whole-wheat pasta
Brown or wild rice
Whole grain cereal
Popcorn
Oatmeal
Whole-wheat tortillas
Bulgur
QuinoaWhole grain barley
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WHOLE GRAIN WHOLE WHEAT
http://www.celiac.com/
http://www.celiac.com/http://www.celiac.com/8/13/2019 Nutrition Lecture 8
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Dental Caries
Begin oral hygiene when teeth appear Seek early dental care
Fluoridated water
Fluoridated toothpaste Snacks in moderation
Tooth sealants
Avoid sticky foods
Sugarless gum