EXSS3071 Week 1

Slide 1: Welcome to EXSS3071

• Course: Nutrition for Exercise and Health

• University of Sydney

Slide 2: Mental Health Support for Students

• Free and instant access to mental health support.

• Resources for both local and international students.

• International students have 24/7 access to a safety and wellbeing app.

Slide 3: Mental Health Support Services

• List of mental health support services including:

• University of Sydney Counselling and Psychological Services (CAPS).

• Crisis line for after-hours support.

• Butterfly Foundation for eating disorders.

• Headspace for youth mental health.

• Lifeline for crisis support and suicide prevention.

• Beyond Blue for mental health information.

• Batyr for crisis intervention resources.

Slide 4: Academic Integrity

• Importance of academic honesty in all assessments.

• Submitting own work, taking own exams.

• Properly acknowledging sources.

• Restriction on the use of AI tools like ChatGPT unless permitted.

• Academic Honesty Education Module required for new students.

Slide 5: Generative AI Policy

• Explanation of generative AI (e.g., ChatGPT, DALL-E).

• Differentiation between AI for learning and AI for assessment.

• Some assessments may allow AI with strict guidelines.

• More information available on Canvas.

Slide 6: University Support Services

• Educational Integrity Office for reporting misconduct.

• Learning Hub for academic support and skills development.

• Library resources, including referencing support.

• Counselling and Psychological Services for mental health support.

• Special consideration for illness or misadventure.

• Disability support registration.

• Student organizations: SRC (undergraduate), SUPRA (postgraduate).

Slide 7: Digestion & Absorption Lecture

• Presented by Karla Horlyck (APD, AEP).

• Acknowledgement of contributors.

Slide 8: Learning Outcomes – Digestion & Absorption

• Identifying carbohydrate types.

• Explaining carbohydrate digestion, absorption, transport, and storage.

• Understanding blood glucose control (liver, insulin, glucagon).

• Lipid digestion and ATP production from fatty acids.

• Understanding ketone body formation.

• Digestion and absorption of proteins.

• Differentiation between essential and non-essential amino acids.

Slide 9: Lecture Overview

• Breakdown of digestive tract function.

• Digestion & absorption of carbohydrates, fats, and proteins.

Slide 10: Digestive Tract Components

• Mouth & esophagus: Mechanical breakdown, increases surface area.

• Stomach: Temporary storage, mixing.

• Small intestine: Primary site of digestion & absorption.

• Gall bladder, liver, pancreas: Digestive enzyme production.

• Large intestine: Water absorption, waste processing.

• Rectum & anus: Elimination.

Slide 11: Types of Carbohydrates

• Monosaccharides: Glucose (sports drinks), Fructose (fruit, honey), Galactose.

• Disaccharides: Maltose (glucose + glucose), Sucrose (glucose + fructose), Lactose (glucose + galactose).

• Oligosaccharides: Maltodextrin (3-9 sugar units).

• Polysaccharides:

• Glycogen (stored in meats, limited).

• Starch (bread, cereals, starchy vegetables).

• Fibre (indigestible, e.g., cellulose).

Slide 12: Chemical Structure of Carbohydrates

• Diagram of different carbohydrate structures.

• Differentiation between mono-, di-, and polysaccharides.

Slide 13: Digestion of Carbohydrates

• Mouth: Salivary amylase breaks down starch into smaller polysaccharides & maltose.

• Stomach: Acid inactivates amylase, halting carbohydrate digestion.

• Small Intestine: Pancreatic amylase continues digestion, breaking starch into disaccharides.

Slide 14: Enzymatic Breakdown of Carbohydrates

• Disaccharides hydrolyzed into monosaccharides by enzymes:

• Maltase: Maltose → Glucose + Glucose.

• Sucrase: Sucrose → Fructose + Glucose.

• Lactase: Lactose → Galactose + Glucose.

• Digestion is mostly complete 1-4 hours after a meal.

• Fibre remains undigested and undergoes fermentation in the large intestine.

Slide 15: Carbohydrate Absorption

• Monosaccharides (glucose, fructose, galactose) absorbed by active transport into the blood.

• Transported to the liver via the portal vein.

• Liver converts fructose and galactose into glucose.

• Glucose circulates in the blood for energy.

Slide 16: Storage of Glucose as Glycogen

• Liver stores and releases glucose as needed.

• About 1/3 of glycogen is stored in the liver.

• When blood glucose falls, glycogen is broken down into glucose and released into the bloodstream.

Slide 17: Blood Glucose Regulation

• All body cells depend on glucose.

• Brain, retina, nervous tissue can’t store glucose.

• Blood glucose maintained between 4-8 mmol/L.

• Hormones regulating blood glucose:

• Insulin: Moves glucose into cells for storage.

• Glucagon: Releases stored glucose from cells into the blood.

• Gluconeogenesis: When no carbs are available, glucose is made from protein.

Slide 18: Lipid Intake

• Daily intake:

• Triglycerides: 50-100g.

• Cholesterol: 300-450mg.

• Phospholipids: 4-8g.

• Triglycerides must be broken down into smaller molecules for absorption.

Slide 19: Digestion & Absorption of Lipids

• Mouth: Some fats melt, salivary lipase starts digestion.

• Stomach: Minimal digestion occurs.

• Small Intestine:

• Cholecystokinin (CCK): Stimulates gall bladder to release bile.

• Liver: Produces bile from cholesterol.

• Pancreatic Lipase: Breaks triglycerides into glycerol and free fatty acids.

Slide 20: Lipid Transport & Absorption

• Fats form chylomicrons in intestinal cells.

• Chylomicrons enter the lymphatic system, then the bloodstream.

Slide 21: Lipid Utilization & Storage

• Triglycerides delivered to body cells.

• Most triglycerides stored in adipose tissue.

• Some stored in muscle (intramuscular triglycerides, IMT).

• Lipoprotein lipase (LPL): Breaks triglycerides into fatty acids for absorption.

Slide 22: Lipid Breakdown for Energy

• Hormone-Sensitive Lipase (HSL) breaks down triglycerides into glycerol and free fatty acids (FFA).

• FFA attach to albumin for transport in the blood.

• FFAs used for ATP production via β-oxidation.

Slide 23: Releasing Lipids from Cells for Fuel

• Stored triglycerides (TG) in adipose tissue are mobilized when energy is needed.

• Hormone-Sensitive Lipase (HSL) activates and hydrolyzes triglycerides into:

• Glycerol (which can enter glycolysis for energy).

• Free Fatty Acids (FFA) (which travel to tissues for β-oxidation).

• FFAs do not dissolve in blood and must bind to albumin for transport.

• The combination of FFAs + albumin is known as Non-Esterified Fatty Acids (NEFA).

• NEFA are taken up by body cells, where they undergo β-oxidation in the mitochondria to produce ATP.

Slide 24: Making Ketone Bodies

• Ketone bodies are produced when fat is broken down rapidly and carbohydrate intake is low.

• This occurs during:

• Fasting/starvation.

• Uncontrolled diabetes (insulin deficiency).

• Low-carbohydrate diets (e.g., Atkins diet).

• Three types of ketone bodies:

• Acetoacetate (primary ketone body).

• β-hydroxybutyrate (most abundant in blood).

• Acetone (least used, excreted in breath).

• Excessive ketone production leads to ketoacidosis, a dangerous condition in diabetics.

Slide 25: Carbohydrate Requirement to Prevent Ketosis

• 50-100g of carbohydrate per day is needed to prevent excessive ketone formation.

• The average carbohydrate intake for most people is 200-300g per day.

• Ketosis is commonly observed in:

• People with severe starvation or fasting.

• Patients with anorexia nervosa.

• Uncontrolled insulin-dependent diabetics.

• Individuals on extreme low-carb diets.

Slide 26: Which Tissues Use Ketones?

• Most tissues (except the liver) can use ketone bodies for energy.

• The brain usually depends on glucose, but in prolonged fasting, it adapts to use ketones.

• Blood-brain barrier:

• FFAs cannot cross the blood-brain barrier.

• Ketones can cross and are converted back to Acetyl-CoA to fuel the TCA cycle (Krebs cycle).

Slide 27: Amino Acids and Protein Structure

• Amino acids are the building blocks of proteins.

• Structure includes:

• A central carbon (C) backbone.

• An amine group (NH2).

• A carboxyl (acid) group (COOH).

• A unique side chain (R group), which determines the amino acid’s properties.

• Peptide bonds link amino acids to form proteins.

Slide 28: Essential vs. Non-Essential Amino Acids

• Essential Amino Acids (must be obtained from diet):

• Histidine, Valine, Leucine, Isoleucine, Lysine, Methionine, Threonine, Phenylalanine, Tryptophan.

• Non-Essential Amino Acids (can be synthesized by the body):

• Glycine, Alanine, Cysteine, Serine, Aspartate, Asparagine, Glutamate, Glutamine, Arginine, Proline.

Slide 29: Protein Digestion & Absorption

• Stomach:

• Pepsinogen (inactive enzyme) is activated by stomach acid (HCl) to form Pepsin.

• Pepsin begins protein breakdown into smaller peptides.

• Small Intestine:

• Pancreatic enzymes (proteases): Trypsin, Chymotrypsin, and Carboxypeptidase break down peptides further.

• Brush border enzymes: Dipeptidase and aminopeptidase complete digestion into individual amino acids.

• Absorption:

• Amino acids are absorbed via active transport into intestinal cells.

• Transported to the liver via the portal vein for metabolism.

Slide 30: End of Part 1

• Transition to the next lecture topic: Introduction to Nutrition.

Slide 31: Introduction to Nutrition

• Presenter: Karla Horlyck (APD, AEP).

• Focus on basic nutrients, dietary guidelines, and energy balance.

Slide 32: Learning Outcomes – Introduction to Nutrition

• Identify macro- and micronutrients.

• Understand Atwater factors (calculation of energy in food).

• Differentiate between nutrient reference values (NRVs).

• Learn about dietary guidelines in Australia and other countries.

Slide 33: Introduction to Nutrition Topics

• Overview of key concepts:

• Nutrients

• Nutrient Reference Values (NRVs)

• Dietary Guidelines

Slide 34: Nutrient Categories

• Macronutrients: Provide energy (Carbohydrates, Fats, Proteins).

• Micronutrients: Required in small amounts, do not provide energy (Vitamins, Minerals).

• Water: Essential for metabolism and homeostasis.

Slide 35: Nutrient Composition of Bread

• Example: 1 slice of multigrain bread contains:

• Carbohydrates: 15.6g

• Fibre: 1.58g

• Protein: 4.36g

• Fat: 0.86g

• Water: 13.54g

Slide 36: Food as a Source of Nutrients

• Foods contain multiple nutrients, not just one.

• Examples:

• Bread is high in carbohydrates, but also contains protein and fibre.

• Milk is a source of calcium, but also has carbs, protein, and fat.

Slide 37: Macronutrients Provide Energy

• Measured in Kilojoules (kJ) or Calories (kcal).

• Macronutrients and their energy values:

• Protein: 17 kJ/g

• Fat: 37 kJ/g

• Carbohydrates: 17 kJ/g

• Alcohol: 29 kJ/g

Slide 38: Dietary Fibre

• Definition: Non-digestible carbohydrates that contribute to gut health.

• Types:

• Soluble Fibre: Lowers cholesterol, stabilizes blood glucose (e.g., oats, legumes).

• Insoluble Fibre: Aids digestion, prevents constipation (e.g., whole grains, vegetables).

• Resistant Starch: Fermented in the large intestine, promotes gut bacteria.

• Health benefits: Improves digestion, reduces heart disease risk, regulates blood sugar.

Slide 39: Energy Balance and Metabolism

• Energy Intake vs. Energy Expenditure:

• Excess intake → Weight gain

• Deficit intake → Weight loss

• Basal Metabolic Rate (BMR): Minimum energy required to maintain vital functions.

• Thermic Effect of Food (TEF): Energy required to digest and metabolize food.

Slide 40: Atwater Factors

• Atwater factors are used to estimate the energy value of food components.

• Energy values per gram:

• Protein: 17 kJ/g (4 kcal/g)

• Fat: 37 kJ/g (9 kcal/g)

• Carbohydrates: 17 kJ/g (4 kcal/g)

• Alcohol: 29 kJ/g (7 kcal/g)

• 1 kcal = 4.184 kJ

Slide 41: Diet Calculation Example

• A sample meal:

• 1 slice of bread: 2g protein, 15g carbohydrate, 0g fat

• 1 tsp butter: 4g fat

• 1 nip scotch: 10g alcohol

• 1 egg: 6g protein, 6g fat

• 300ml milk: 10g protein, 12g fat, 14g carbohydrate

• Energy calculation using Atwater factors:

• Protein: 18g × 17 kJ/g = 306 kJ

• Fat: 22g × 37 kJ/g = 814 kJ

• Carbohydrates: 29g × 17 kJ/g = 493 kJ

• Alcohol: 10g × 29 kJ/g = 290 kJ

• Total energy intake: 1,903 kJ

Slide 42: Energy Distribution in the Diet

• Total energy intake (1,874 kJ) distributed as follows:

• Protein: (306 kJ ÷ 1,874 kJ) × 100 = 16.2%

• Fat: (814 kJ ÷ 1,874 kJ) × 100 = 43.4%

• Carbohydrates: (464 kJ ÷ 1,874 kJ) × 100 = 24.8%

• Alcohol: (290 kJ ÷ 1,874 kJ) × 100 = 15.5%

• Acceptable Macronutrient Distribution Range (AMDR) for Australians:

• Protein: 15–25%

• Fat: 20–35%

• Carbohydrates: 45–65%

Slide 43: Micronutrients

• Micronutrients are needed in small amounts (mg or μg).

• Do not provide energy but are essential for enzyme function.

• Categories:

• Vitamins: Fat-soluble (A, D, E, K) and water-soluble (B-complex, C).

• Minerals: Major minerals (calcium, potassium, sodium) and trace elements (iron, zinc, iodine).

Slide 44: Vitamins Overview

• Fat-Soluble Vitamins (stored in fat tissue):

• Vitamin A, D, E, K

• Water-Soluble Vitamins (excreted in urine, not stored):

• B vitamins (B1, B2, B3, B6, B12, folate, pantothenic acid, biotin)

• Vitamin C

• Roles of vitamins:

• Vitamin C: Antioxidant, collagen synthesis.

• B vitamins: Metabolism of macronutrients.

• Vitamin A: Vision and immune function.

Slide 45: Preserving Vitamins in Food

• Methods to retain vitamin content:

• Minimize cooking time and use little water.

• Avoid soaking vegetables.

• Limit exposure to air and light.

• Avoid using baking soda when cooking vegetables.

• Store fresh food properly and consume quickly.

Slide 46: Minerals Overview

• Major minerals:

• Calcium: Bone health, muscle contraction.

• Iron: Oxygen transport (hemoglobin).

• Potassium, Magnesium, Sodium: Electrolyte balance.

• Trace minerals:

• Zinc: Immune function, wound healing.

• Copper: Red blood cell formation.

• Iodine: Thyroid hormone production.

Slide 47: Nutrients in Food Example (Multigrain Bread)

• Macronutrients:

• Carbohydrates: 16.9g

• Fibre: 1.58g

• Protein: 3.4g

• Fat: 0.83g

• Micronutrients:

• Thiamin: 0.15mg

• Riboflavin: 0.02mg

• Niacin: 1.03mg

• Folate: 102.96μg

• Sodium: 144mg

• Magnesium: 26mg

• Calcium: 34mg

Slide 48: How Much Do We Need?

• Nutrient requirements depend on:

• Age and gender

• Body size and weight

• Physiological state (e.g., pregnancy, lactation)

• Individual variations (safety margins apply to RDIs)

Slide 49: Nutrient Reference Values (NRVs)

• Reference values that determine nutrient intake recommendations:

• Recommended Dietary Intake (RDI)

• Estimated Average Requirement (EAR)

• Adequate Intake (AI)

• Upper Limit (UL)

Slide 50: Definitions of NRVs

• EAR (Estimated Average Requirement):

• Nutrient intake that meets 50% of healthy individuals in a population.

• RDI (Recommended Dietary Intake):

• Meets the needs of 97-98% of healthy individuals.

• AI (Adequate Intake):

• Used when EAR and RDI are unavailable.

• UL (Upper Limit):

• Maximum safe level of intake before risk of toxicity.

Slide 51: Estimated Energy Requirement (EER)

• The average dietary intake that maintains energy balance in a healthy individual.

• Factors affecting EER:

• Age, gender, weight, height, physical activity level.

Slide 52: How Much Is Enough?

• Nutrient recommendations vary by:

• Age group

• Gender

• Pregnancy/lactation

Slide 53: NRVs and Their Application

• NRVs are used for population-level dietary planning.

• Not designed for individual assessments.

Slide 54: Suggested Dietary Targets (SDT) for Chronic Disease Prevention

• SDT represents nutrient intakes linked to reducing chronic disease risk.

• Example: Higher fibre intake is linked to lower heart disease risk.

Slide 55: Australian Suggested Dietary Targets (SDT)

• Guidelines set by the NHMRC for optimal health.

Slide 56: Acceptable Macronutrient Distribution Range (AMDR)

• Recommended proportion of daily energy intake:

• Protein: 15–25%

• Fat: 20–35%

• Carbohydrates: 45–65%

Slide 57: How Are NRVs Determined?

• Based on scientific evidence of nutrient requirements.

Slide 58: Communicating a Healthy Diet in Australia

• Australian Guide to Healthy Eating (AGHE).

• National Dietary Guidelines.

Slide 59: Australian Dietary Guidelines (ADG)

• Provides science-based recommendations for healthy eating.

• Designed to promote long-term health and reduce chronic disease risk.

Slide 60: US MyPlate Guide to Healthy Eating

• Comparison with Australian dietary guidelines.

Slide 61: Nutrition Australia Healthy Eating Pyramid

• Visual representation of a balanced diet.

Slide 62: AGHE Food Groups

• Vegetables, grains, proteins, dairy, fruits.

Slide 63: Limitations of AGHE

• Does not specify portion sizes or mixed foods.

Slide 64: End of Lecture

• Conclusion and next steps in learning about dietary assessment methods.

Slide 65: Nutritional Characteristics of the Five Food Groups

• Five core food groups from the Australian Guide to Healthy Eating (AGHE):

1. Vegetables, legumes, beans – Provide fibre, vitamins (A, C, K), and minerals.

2. Fruits – Rich in vitamins (C), fibre, and natural sugars.

3. Grain (cereal) foods – Major source of carbohydrates, fibre, B vitamins, and iron.

4. Lean meats, poultry, fish, eggs, tofu, nuts, seeds, legumes – Provide protein, iron, zinc, and B vitamins.

5. Milk, yoghurt, cheese (and alternatives) – Main source of calcium and protein.

Slide 66: Nutritional Characteristics of the Five Food Groups (Continued)

• Each food group provides essential nutrients for different bodily functions.

• Balanced intake of all five groups supports optimal health and reduces chronic disease risk.

Slide 67: What Doesn’t the Plate Tell Me?

• The AGHE plate model does not provide information on:

• Exact serve sizes for different life stages (children, elderly, athletes, etc.).

• How many serves are required per food group per day.

• Age and gender-specific variations in dietary needs.

• How much oil/fat should be consumed for a balanced diet.

• Guidance on discretionary (sometimes) foods like snacks and treats.

• How to categorize mixed foods (e.g., pizza, casseroles).

• Solution: Refer to the AGHE Educator’s Guide and consumer brochures for more detailed guidance.

Slide 68: Quirks of the Australian Guide to Healthy Eating (AGHE)

• Unusual categorization of some foods:

• Legumes and lentils are in two food groups (vegetables AND meat/meat alternatives).

• Tomatoes classified as vegetables (culinary), but botanically, they are fruits.

• Fats and oils are not considered a food group, even though healthy fats are essential.

• Milk alternatives (e.g., almond milk) must be fortified with calcium (≥100mg per 100mL) to be a proper dairy substitute.

Slide 69: More on the AGHE and Dietary Intake Assessment Methods

• Further discussion on dietary assessment methods in upcoming tutorials.

• Students will learn how to apply dietary guidelines in practical settings.

Slide 70: End of Lecture – Thank You!

• Conclusion of the lecture on Nutrition for Exercise and Health.

• Encouragement to use course materials and recommended readings for deeper understanding.