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LAST TIME WE TALKED ABOUT
CANADA’S FOOD GUIDE DRIs FOOD LABELLING SIX DIETARY PRINCIPLES ALL IMPORTANT TO ENSURE GOOD NUTRITION FOR THE ATHLETE NOW ONTO CARBOHYDRATE METABOLISM
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Overview of lecture 5 Carbohydrates -carbohydrates we digest -structure and classification -IDATME -lactose intolerance, blood glucose homeostasis, glycaemic index -choosing carbohydrates wisely -roles of carbohydrates -carbohydrates digested by bacteria -fibre-structure, classification and effects -fibre in the diet -too much fibre in diet
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INTRODUCTION CARBOHYRATES:
-COMMONLY REFERRED TO AS SUGARS BUT THIS IS NOT COMPLETELY ACCURATE -CONTAIN CARBON -CONTAIN HYDROGEN AND OXYGEN IN THE SAME PROPORTION AS WATER
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INTRODUCTION CONTINUED
- YIELD ENERGY (GLUCOSE) AND STORE ENERGY (GLYCOGEN) -VERY IMPORTANT FOR NERVE AND MUSCLE FUNCTION AMONG MANY OTHER FUNCTIONS
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STRUCTURE AND CLASSIFICATION
SIMPLE MONOSACCHARIDES DISACCHARIDES
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CARBOHYDRATE STRUCTURE
CLASSIFICATION CONTINUED COMPLEX OLIGOSACCHARIDES– 3-10 SUGAR UNITS
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CARBOHYDRATE STRUCTURE
CLASSIFICATION CONTINUED COMPLEX CONTINUED POLYSACCHARIDES MANY SUGAR UNITS STRUNG TOGETHER GLYCOGEN STARCH FIBRE
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Figure 4.9: Starch and Cellulose Molecules Compared (Small Segments).
The bonds that link the glucose molecules together in cellulose are different from the bonds in starch (and glycogen). Human enzymes cannot digest cellulose. See Appendix C for chemical structures and descriptions of linkages. Fig. 4-9, p. 102
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Figure 4.8: Glycogen and Starch Molecules Compared (Small Segments).
These units would have to be magnified millions of times to appear at the size shown in this figure. For details of the chemical structures, see Appendix C. Fig. 4-8, p. 101
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CARBOHYDRATES DIGESTION MOUTH-AMYLASE STOMACH-ACID-MINIMAL
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CARBOHYDRATE DIGESTION CONTINUED
SMALL INTESTINE -MOST OF CARBOHYDRATE DIGESTION IN BODY OCCURS IN THE SMALL INTESTINE: -SMALL INTESTINE USES PANCREATIC CARBOHYDRASES and SMALL INTESTINAL CARBOHYDRASES
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Figure 4.10: Carbohydrate Digestion in the GI Tract.
Fig. 4-10, p. 104
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CARBOHYDRATE DIGESTION CONTINUED
MINIMAL DIGESTION BY HUMANS OF FIBRES AND SOME RESISTANT CARBOHYDRATES (e.g. RESISTANT STARCHES)
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CARBOHYDRATE DIGESTION CONTINUED
file:///D:/Media/Animations/chapter4/Carbohydrate_Digestion/0410update.html
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LACTOSE INTOLERANCE INTOLERANCE IS NOT AN ALLERGY-ALLERGIES DUE TO PROTEINS AND OTHER AGENTS THAT PRODUCE AN ALLERGIC RESPONSE
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LACTOSE INTOLERANCE IS DUE TO :
REDUCTION IN THE: AMOUNT AND/OR ACTIVITY OF LACTASE-CAN BE UP TO 90-95 % LOSS OVER TIME STRONG GENETIC COMPONENT
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SYMPTOMS OF LACTOSE INTOLERANCE
GAS, ACIDS FROM BACTERIAL DIGESTION OF LACTOSE RESULTING IN CRAMPS, ABDOMINAL DISTENSION, DIARRHEA AND BLOATING
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CONSEQUENCES OF LACTOSE
INTOLERANCE DAIRY PRODUCTS-CALCIUM HAVE TO FIND ALTERNATE CALCIUM SOURCES OR USE AN ORAL LACTASE OR USE A LACTASE ADDED TO DAIRY PRODUCT
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CARBOHYDRATES ABSORPTION
GLUCOSE and GALACTOSE ACTIVE TRANSPORT FRUCTOSE-FACILITATED DIFFUSION
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CARBOHYDRATES TRANSPORT
FRUCTOSE, GLUCOSE, GALACTOSE VIA BLOOD
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CARBOHYDRATES METABOLISM
UP NEXT
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METABOLISM OF CARBOHYDRATES
INSULIN –GLUCOSE INTO CELLS FOR ENERGY OR TO GLYCOGEN(PRIMARILY LIVER AND MUSCLE) -GLYCOGEN-STORAGE FORM OF GLUCOSE PRIMARILY IN MUSCLE AND LIVER GLUCAGON- GLYCOGEN TO GLUCOSE IN CELL- GLUCOSE LEAVES CELL AND ENTERS THE BLOOD-ENERGY
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Figure 4.12: Maintaining Blood Glucose Homeostasis.
Fig. 4-12, p. 109
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BLOOD GLUCOSE HOMEOSTASIS
Maintaining-too low-dizzy and weak too high-fatigued, confused and difficulty breathing Regulating hormones - insulin and glucagon Balancing in normal range - insulin and glucagon
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BLOOD GLUCOSE AND DIET CONTINUED-GLYCAEMIC INDEX
A scale that ranks carbohydrate-rich foods by how much they raise blood glucose levels compared to a standard food (e.g. white bread). Standard food is given a score of 100
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BLOOD GLUCOSE AND DIET CONTINUED
-however, glycemic index is controversial - inadequate science? - determined for relatively few foods - when determined it is based on average of multiple tests with a great deal of variability
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FOODS GLYCEMIC INDEX GRAINS (INCLUDES BREADS AND PASTAS)
BREADS -WHEAT HIGHER THAN RYE PASTAS - LOWER THAN BREADS RICE AND PASTA ABOUT THE SAME AS EACH OTHER
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GLYCEMIC INDEX CONTINUED
FOODS CONTINUED GLYCEMIC INDEX CONTINUED VEGETABLES AND FRUITS ON AVERAGE GLYCEMIC INDEX POTATO > YAM LEGUMES > ROOT VEGGIES FRUITS ~ LEGUMES
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FOODS CONTINUED GLYCEMIC INDEX CONTINUED MILK PRODUCTS ~ FRUITS ON AVERAGE WHY? LACTOSE=FRUCTOSE IN GLYCEMIC INDEX
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FOODS CONTINUED GLYCEMIC INDEX CONTINUED MEATS - VERY LOW GLYCEMIC INDEX - BUT DO NOT GORGE
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CARBOHYDRATE EXCRETION
URINE- WATER, LITTLE SUGAR FAECES- WATER, LITTLE SUGAR LUNGS- CO2 SALIVA? PARTIALLY DIGESTED CARBS?
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How to choose carbohydrates wisely
1)increase intakes of whole grains 2)use whole grain products such as oatmeal, brown rice and whole wheat bread 3)increase consumption of legumes such as kidney, black and pinto beans)if fresh fruits not available, choose frozen or canned fruits without added sugar
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How to choose carbohydrates wisely continued
4)use whole grain flour for ¼ to ½ the amount of flour in the recipe 5)use less sugar in baking 6)use less added sugars in foods 7)eat fewer high sugar foods 8)use food labels to guides one’s choices
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BLOOD GLUCOSE AND DIET CONTINUED
FAD DIETS -NO APPLES OR ORANGES BUT BACON AND EGGS ALRIGHT-THIS IS NOT GOOD WHY? -AVOID OUTRIGHT!
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CARBOHYDRATES ESSENTIAL OR NOT?
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YES- WHY? HEALTHY ROLES 1) NEURAL FUNCTION 2) GIVE STRUCTURE TO MOLECULES 3) METABOLICALLY 4) IMPACT ON NUTRIENT ABSORPTION
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CARBOHYDRATE FUNCTIONS- HEALTHY
NEURAL FUNCTION BRAIN AND NERVES REALLY ONLY SET UP TO USE GLUCOSE LIPIDS/PROTEINS CANNOT BE USED
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CARBOHYDRATE FUNCTIONS- HEALTHY continued
GIVE STRUCTURE TO MOLECULES CARBOHYDRATE E.G. GLYCOGEN DISACCHARIDES OLIGOSACCHARIDES NON-CARBOHYDRATE E.G. SOME PROTEINS
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CARBOHYDRATE FUNCTIONS- HEALTHY continued METABOLICALLY
ENERGY -HEAT/FUEL -SPARING PROTEIN -BURNING FAT
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CARBOHYDRATE FUNCTIONS- HEALTHY continued
METABOLICALLY CONTINUED MAKE OTHER COMPOUNDS - GLYCOGEN - FAT - PROTEIN (NON-ESSENTIAL AMINO ACIDS) - DNA/RNA
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CARBOHYDRATE FUNCTIONS- HEALTHY continued IMPACT ON NUTRIENT HANDLING
non-absorbable oligosaccharides impair carbohydrase activity starch granules exposed to moist heat and then cooling are less dense and hence less available to enzyme action
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Fibre structure and classification and effects
Insoluble Cellulose-bran,vegetables Hemicellulose-bran, whole grains Lignins-fruits, mature vegetables, flax Generally-accelerate gi transit, increase fecal weight(promotes bowel movements), slow starch digestion, delay glucose absorption But can be exceptions
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Fibre structure and classification and effects continued
Soluble Pectins-apples, carrots gums and mucilages- oats, legumes Generally-delay gi transit, delay glucose absorption, lower blood cholesterol But can be exceptions
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OTHER FIBRE FUNCTIONS (classifications)
- water holding capacity viscosity cation exchange capacity bile binding capacity fermentability
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How to get higher fibre in the diet
Fibre content High Medium Low Breads cereal g 2 g g Rice Group Breads Whole wheat white 1 slice bread bread Cereal All shredded rice ½ cup bran wheat krispies Pasta Whole macaroni ½ cup wheat pasta
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How to get higher fibre in the diet continued
Fibre content High Medium Low 4 g 2 g 1 g Fruit group 1 MEDIUM OR ½ CUP berries apple melon
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How to get higher fibre in the diet continued
Fibre content High Medium Low 4 g g 1 g Vegetable group peas green asparagus ½ CUP beans
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DRI RECOMMENDATION FOR FIBRE INTAKE
FOLLOW DRI RECOMMENDATIONS FOR CARBOHYDRATE INTAKE AND THIS WILL PROVIDE SUFFICIENT FIBRE DRI - 14 GRAMS FIBRE/1000 KCAL (ROUGHLY GRAMS OF FIBRE/DAY) (NO DISTINCTION BETWEEN SOLUBLE AND INSOLUBLE BUT VARIETY IS THE KEY TO BALANCE)
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REMEMBER THAT: FIBRE FROM NATURAL SOURCES RATHER THAN COMMERCIALLY PREPARED FIBRE IS BETTER BECAUSE FOODS CONTAIN VITAMINS AND MINERALS AS WELL AS THE FIBRE
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FIBRE IDATME ingestion-fibre containing foods – grains, fruits and vegetables not digested by small intestine enzymes-why? bacteria-make short chain fatty acids and gas short chain fatty acids absorbed at large intestine and transported by blood used for energy excretion-whole or in part, gas, short chain fatty acids
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TOO MUCH FIBRE IN THE DIET
FLATULENCE OBSTRUCT GI TRACT IF GREATER THAN 50 G FIBRE /DAY TOP RECOMMENDATION IS 40 G/D FOR ADULTS (WHO)
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TOO MUCH FIBRE IN THE DIET CONTINUED
INSOLUBLE FIBRE HAS PHYTATES THAT CAN BIND MINERALS- EG CALCIUM, IRON, ZINC AND MAGNESIUM PREVENT ENZYME CONTACT
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TOO MUCH FIBRE IN THE DIET CONTINUED
INCREASES VOLUME OF FOOD REQUIRED TO MEET ENERGY REQUIREMENTS SATIETY BEFORE ADEQUATE NUTRITION-GENERALLY ONLY A PROBLEM IF DIET LOW IN MICRONUTRIENTS OR IN SMALL CHILDREN (SMALL STOMACHS)
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TOO MUCH FIBRE IN THE DIET CONTINUED
IMPORTANT TO INCREASE WATER INTAKE WITH INCREASES IN DIETARY FIBRE -OTHERWISE CONSTIPATION BUT IF HAVE TOO MUCH WATER CAN GET DIARRHEA (BACTERIAL BREAKDOWN OF FIBRE)
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Summary of lecture 5 Carbohydrates -carbohydrates we digest -structure and classification -IDATME -lactose intolerance, blood glucose homeostasis, glycaemic index -choosing carbohydrates wisely -roles of carbohydrates -carbohydrates digested by bacteria -fibre-structure, classification and effects -fibre in the diet -too much fibre in diet
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NEXT TIME WE WIILL TAKE TODAY’S LECTURE
AND APPLY IT TO CARBOHYDRATES IN ANAEROBIC, INTERVAL AND AEROBIC SPORTS
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