nutrition lecture 8

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



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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
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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/


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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

nutrition lecture 8

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