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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

53

OTHER FIBRE FUNCTIONS (classifications)

- water holding capacity- viscosity- cation exchange capacity- bile binding capacity- fermentability

54

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

57

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

60

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)

61

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)

63

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