Carbohydrates
description
Transcript of Carbohydrates
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