Jan 11, 2016
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LAST TIME WE TALKED ABOUT
CANADA’S FOOD GUIDEDRIs
FOOD LABELLINGSIX DIETARY PRINCIPLES
ALL IMPORTANT TO ENSURE GOOD NUTRITION FOR THE ATHLETE
NOW ONTO CARBOHYDRATE METABOLISM
Overview of lecture 5Carbohydrates
-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
-IDATME -too much fibre in diet
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
INTRODUCTION CONTINUED
- YIELD ENERGY (GLUCOSE) AND STORE ENERGY (GLYCOGEN)
-VERY IMPORTANT FOR NERVE AND MUSCLE FUNCTION AMONG MANY OTHER FUNCTIONS
STRUCTURE AND CLASSIFICATION
SIMPLE
MONOSACCHARIDESDISACCHARIDES
CARBOHYDRATE STRUCTURE CLASSIFICATION CONTINUED
COMPLEX
OLIGOSACCHARIDES–3-10 SUGAR UNITS
CARBOHYDRATE STRUCTURE CLASSIFICATION CONTINUED
COMPLEX CONTINUED POLYSACCHARIDES MANY SUGAR UNITS STRUNG TOGETHER
GLYCOGEN STARCH FIBRE
Fig. 4-9, p. 102
Fig. 4-8, p. 101
CARBOHYDRATES DIGESTION
MOUTH-AMYLASE
STOMACH-ACID-MINIMAL
CARBOHYDRATE DIGESTION CONTINUED SMALL INTESTINE
-MOST OF CARBOHYDRATE DIGESTION IN BODY OCCURS IN THE SMALL INTESTINE:
-SMALL INTESTINE USES PANCREATIC CARBOHYDRASESand SMALL INTESTINAL CARBOHYDRASES
Fig. 4-10, p. 104
CARBOHYDRATE DIGESTION CONTINUED
MINIMAL DIGESTION BY HUMANSOF FIBRES AND SOME RESISTANTCARBOHYDRATES (e.g. RESISTANT STARCHES)
CARBOHYDRATE DIGESTION CONTINUED
file:///D:/Media/Animations/chapter4/Carbohydrate_Digestion/0410update.html
LACTOSE INTOLERANCE
INTOLERANCE IS NOT AN ALLERGY-ALLERGIES DUE TO PROTEINS AND OTHER AGENTS THAT PRODUCE AN ALLERGIC RESPONSE
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
SYMPTOMS OF LACTOSE INTOLERANCE
GAS, ACIDS FROM BACTERIAL DIGESTION OF LACTOSERESULTING IN CRAMPS, ABDOMINAL DISTENSION, DIARRHEA AND BLOATING
CONSEQUENCES OF LACTOSE INTOLERANCE
DAIRY PRODUCTS-CALCIUMHAVE TO FIND ALTERNATECALCIUM SOURCES
OR USE AN ORAL LACTASE OR USE A LACTASE ADDED TO DAIRYPRODUCT
CARBOHYDRATES ABSORPTION
GLUCOSE and GALACTOSE ACTIVE TRANSPORT
FRUCTOSE-FACILITATEDDIFFUSION
CARBOHYDRATES TRANSPORT
FRUCTOSE, GLUCOSE, GALACTOSE VIA BLOOD
CARBOHYDRATES METABOLISM
UP NEXT
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
Fig. 4-12, p. 109
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
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 isgiven a score of 100
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
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
FOODS CONTINUED GLYCEMIC INDEX CONTINUED VEGETABLES AND FRUITS ON AVERAGE
GLYCEMIC INDEX
POTATO > YAM
LEGUMES > ROOT VEGGIES
FRUITS ~ LEGUMES
FOODS CONTINUED
GLYCEMIC INDEX CONTINUED
MILK PRODUCTS ~ FRUITS ON AVERAGE
WHY? LACTOSE=FRUCTOSEIN GLYCEMIC INDEX
FOODS CONTINUED GLYCEMIC INDEX CONTINUED
MEATS - VERY LOW GLYCEMIC INDEX
- BUT DO NOT GORGE
CARBOHYDRATE EXCRETION
URINE- WATER, LITTLE SUGAR FAECES- WATER, LITTLE SUGAR
LUNGS- CO2
SALIVA? PARTIALLY DIGESTED CARBS?
41
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
42
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
BLOOD GLUCOSE AND DIET CONTINUED
FAD DIETS
-NO APPLES OR ORANGES BUT BACONAND EGGS ALRIGHT-THIS IS NOTGOOD WHY?
-AVOID OUTRIGHT!
CARBOHYDRATESESSENTIAL OR NOT?
YES- WHY?
HEALTHY ROLES
1) NEURAL FUNCTION 2) GIVE STRUCTURE TO MOLECULES 3) METABOLICALLY 4) IMPACT ON NUTRIENT
ABSORPTION
CARBOHYDRATE FUNCTIONS-HEALTHY
NEURAL FUNCTION
BRAIN AND NERVES REALLY ONLY SET UP TO USE GLUCOSE
LIPIDS/PROTEINS CANNOT BE USED
CARBOHYDRATE FUNCTIONS-HEALTHY continued
GIVE STRUCTURE TO MOLECULES
CARBOHYDRATE E.G. GLYCOGEN
DISACCHARIDES OLIGOSACCHARIDES
NON-CARBOHYDRATE E.G. SOME PROTEINS
CARBOHYDRATE FUNCTIONS-HEALTHY continued
METABOLICALLY
ENERGY -HEAT/FUEL -SPARING PROTEIN -BURNING FAT
CARBOHYDRATE FUNCTIONS-HEALTHY continued
METABOLICALLY CONTINUED
MAKE OTHER COMPOUNDS - GLYCOGEN - FAT - PROTEIN (NON-ESSENTIAL
AMINO ACIDS) - DNA/RNA
CARBOHYDRATE FUNCTIONS-HEALTHY continued
IMPACT ON NUTRIENT HANDLING
• non-absorbable oligosaccharidesimpair carbohydrase activity
• starch granules exposed to moist heat and then cooling are less
dense and hence less available to enzyme action
51
Fibre structure and classification and effectsInsoluble 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
52
Fibre structure and classification and effects continued
SolublePectins-apples, carrotsgums 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 dietFibre content
High Medium LowBreads cereal 5g 2 g 0.5 gRice GroupBreads Whole wheat white1 slice bread bread
Cereal All shredded rice ½ cup bran wheat krispies
Pasta Whole macaroni½ cup wheat pasta
55
How to get higher fibre in the diet continued
Fibre content High Medium Low 4 g 2 g 1 g
Fruit group1 MEDIUMOR ½ CUP berries apple melon
56
How to get higher fibre in the diet continued Fibre content
High Medium Low4 g 2 g 1 g
Vegetablegroup
peas green asparagus½ 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 25-35 GRAMS OF FIBRE/DAY) (NO DISTINCTION BETWEEN
SOLUBLE AND INSOLUBLE BUT VARIETY IS THE KEY TO BALANCE)
58
REMEMBER THAT: FIBRE FROM NATURAL SOURCESRATHER THAN COMMERCIALLYPREPARED FIBRE IS BETTER BECAUSE FOODS CONTAIN VITAMINS AND MINERALS AS WELL AS THE FIBRE
59
FIBRE IDATME
• ingestion-fibre containing foods – grains, fruits and vegetables• not digested by small intestine enzymes-why?• bacteria-make short chain fatty acids
water, gas• short chain fatty acids, water absorbed at large intestine
and transported by blood used for energy• excretion-whole or in part, gas water, 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, ZINCAND MAGNESIUM
•PREVENT ENZYME CONTACT
62
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 ENOUGH WATER CAN GET DIARRHEA (BACTERIAL BREAKDOWN OF FIBRE)
Summary of lecture 5Carbohydrates
-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
-IDATME -too much fibre in diet
65
NEXT TIME WE WIILL TAKE TODAY’S LECTUREAND APPLY IT TO CARBOHYDRATES IN ANAEROBIC,INTERVAL AND AEROBIC SPORTS