Carbohydrates

Intended Learning Outcomes

- By the end of this lecture, students will have a

general overview on the carbohydrates.

Fiber structural parts of plants

–found in all plant derived foodbonds of fibers cannot be

broken down during the digestive process–minimal or no energy available

Fiber types

cellulose pectins lignins resistant starches

–classified as fibers–escape digestion and

absorption

Fiber Characteristics soluble fibers, viscous, fermentable

–easily digested by bacteria in colon–associated with protection against

heart disease and diabeteslower cholesterol and glucose levels

–found in legumes and fruits

Fiber1. The average American does not get

enough FIBER in their diets.2. The National Cancer Institute

recommends that the average person gets 20-35 GRAMS of fiber every day.

3. Two other common names for fiber are: ROUGHAGE or CELLULOSE.

4. Fiber is important because it attracts WATER to the INTESTINES and helps move food through our systems faster. You have to have water along with fiber or it is not as effective.

5. Benefits of fiber include a lowered risk of DIVERTICULITUS, HEMORRHOIDS and COLON or RECAL CANCER.

6. List the two types of fiber and the main functions they perform:

Type of Fiber Function

A. Soluble Shown to lower total blood cholesterol

B. Insolubl*Will NOT digest or dissolve

Helps move food through the body

7. Fiber only comes from PLANT food sources. You CANNOT get fiber from animal food sources.

8. Foods that are high in fiber include:• Fruits and Veggies (Especially the

Skins!)• Whole Grains• Legumes/Beans - Bran

9. Ways to increase fiber in the diet include:• Add Whole Grains (At least 3 oz. per

day)• Use Whole Wheat FlourEat the Skins

10. Label the Wheat Kernel below:A.__ENDOSPERM___Provides: Starch ProteinB. __GERM___Provides: Unsaturated Fatty Acids “B” Vitamins Vitamin E Iron Zinc Other Trace Minerals

C. __Bran___Provides: Fiber Vitamins Minerals

11.When a product claims that it is “Whole Wheat” or “Whole Grain”, it must use the ENTIRE wheat kernel, or ALL THREE parts.

12.Other products, like white bread and rice, usually only use the ENDOSPERM, which is the LEAST beneficial part of the wheat kernel.

13.ENRICHED: some of the nutrients that were lost in processing are added back into the product.

14.FORTIFIED: 10% more of the Daily Value for the nutrient is being added.

Fiber

insoluble and not easily fermented–promote bowel movements–alleviate constipation– found in grains and vegetables

DRI and Fiber

distinguish fibers by source–dietary fibers: naturally in intact plants– functional fibers: extracted from plants or

manufactured– total fiber: sum of the 2

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

Carbohydrate Digestion begins in mouth

–chewing releases saliva–enzyme amylase hydrolyzes starch to

polysaccharides and maltose stomach

–no enzymes available to break down starch

–acid does some breakdown– fibers in starch provide feeling of fullness

small intestine majority of carbohydrate digestion takes place herepancreatic amylase reduces carbs to glucose chains or disaccharidesspecific enzymes finish the job

maltasemaltose into 2 glucose

sucrasesucrose into glucose and fructose

lactaselactose into glucose and galactose

large intestine

1-4 hours for sugars and starches to be digested only fibers remain

attract water, which softens stoolbacteria ferment some fibers

water, gas, short-chain fatty acids (used for energy)

Carbohydrate Absorption

glucose can be absorbed in the mouth majority absorbed in small intestine

–active transportglucose and galactic

– facilitated diffusion fructosesmaller rise in blood glucose

Lactose Intolerance more lactose is consumed than can be

digested– lactose molecules attract water

cause floating, abdominal discomfort, diarrhea

– intestinal bacteria feed on undigested lactoseproduce acid and gas

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

Carbohydrate Metabolism 1/3 of body’s glycogen is stored in liver

– released as glucose to bloodstream1. eat – intake glucose2. liver condenses extra glucose to glycogen3. blood glucose falls4. 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.

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

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

maintaining balancebalanced meals at regular intervals

fiber and some fat slow the digestive process downglucose gets into the blood slow and steady

Maintaining Blood

Glucose Homeostasis

Intestine When a person eats,blood glucose rises.

1

2

Insulin stimulates the uptake of glucose into cells and storageas glycogen in the liver and muscles. Insulin also stimulates the conversion of excessglucose into fat for storage.

3

4

5

6

7 Blood glucose begins to rise.

a The stress hormone epinephrine and other hormonesalso bring glucose out of storage.

GlucoseInsulinGlucagonGlycogen

Glucagon stimulates livercells to break down glycogenand release glucose into theblood.a

Liver

Low blood glucose stimulatesthe pancreas to releaseglucagon into the bloodstream.

As the body's cells useglucose, blood levels decline.

Glucagon

Pancreas

Fat cell

Liver

Muscle

High blood glucose stimulatesthe pancreas to release insulin.

Pancreas

Insulin

Imbalance

diabetes–after food intake, blood glucose rises and

is not regulated because insulin is inadequate

hypoglycemia–blood glucose drops dramatically

too much insulin, activity, inadequate food intake, illness

diet adjustment includes fiber-rich carbs and protein

Glycemic Index

way of classifying food according to their ability to raise blood glucose

much controversy

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

Sugar

recommended intake–added sugar = no more than 10% of energy

intake

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 diabetesenhances the health of the large

intestinecan promote weight loss

Starch and Fiber starch intake

–45-65%–225 – 325 grams (DV is 300

grams)–900-1300 kcal/2000 kcal–RDA is 130 grams

fiber intake–Daily Value is 25 grams/2000

kcal

Groceries grains: 1 serving = 15 grams vegetables

–½ cup starchy = 15 grams–½ cup nonstarchy = 5 grams

fruit: 1 serving = 15 grams milk: 1 cup = 12 grams meat: none or little legumes: ½ cup = 15 grams

Artificial Sweeteners help keep sugar and energy intake down anything we eat has FDA approval

–saccharin–aspartame–acesulfame potassium–sucralose–neotame

Recommended text bookManual dietetic book