Principles of Nutrition Lecture Notes PDF

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Principles of Nutrition Class DEM Year 2 Course Gastrointestinal Biology Lecturer Dr. Sarah O’Neill ([email protected]) Date September 9th 2024 LEARNING OUTCOME...

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Principles of Nutrition Class DEM Year 2 Course Gastrointestinal Biology Lecturer Dr. Sarah O’Neill ([email protected]) Date September 9th 2024 LEARNING OUTCOMES At the end of this lecture, you will be able to: 1. Describe the composition and caloric content of the healthy diet 2. Explain the principles of energy balance in the body 3. Explain Basal Metabolic Rate (BMR) and diet-induced thermogenesis (DIT) 4. Explain the concept of Daily Energy Expenditure (DEE) 5. Explain the basics of Dietary Reference Intakes (DRI) 6. Describe the basic concepts of Total Parenteral Nutrition (TPN) 7. Describe essential dietary factors 8. Describe the consequences of nutritional deficiencies and malnutrition in the body  A HEALTHY DIET Emphasis is on fruits, vegetables and whole grains Fat-free or low-fat milk and milk products Includes lean meats, poultry, fish, beans, eggs, and nuts Foods low in saturated fats, cholesterol, salt (sodium) and added sugars COMPOSITION OF A HEALTHY DIET DAILY SERVING GUIDES: A CLOSER LOOK Have a look here  ANOTHER WAY TO LOOK AT IT: The Eatwell Guide How does this compare to the food pyramid? Eatwell Guide at the NHS  SOME IMPORTANT PRINCIPLES OF NUTRITION Adequacy: enough of all essential nutrients Balance: do not rely on one type of food for everything Energy control: do not overeat or not eat enough Moderation: not too much or too little of anything Variety: the spice of life: include a large variety of different foods in your diet Aim for a healthy weight Be physically active 30-60 minutes a day CLASSIFICATION OF NUTRIENTS Macronutrients (required in large quantities: g) – Carbohydrates (organic) – Fats (lipids) (organic) Energy yielding – Protein (organic) Micronutrients (required in small amounts mg or mg) – Vitamins (organic) – Minerals (inorganic) Regulator nutrients Some revision: Have a look at your lectures from FFP1 to remind you about these nutrients ENERGY YIELDING NUTRIENTS CARBOHYDRATES Group of organic compounds PROTEINS: Source of amino acids Sugars/Saccharides – Sucrose – Lactose – Fructose – Glucose Starches carbohydrates Oxidation of COHs yields energy LIPIDS Triglycerides 1. Essential in children for optimal growth and development - 3 fatty acids esterified to 1 glycerol 2. Essential for convalescing patients 3. Essential for critically ill patients Yield more energy when oxidised REGULATOR NUTRIENT: VITAMINS Organic molecules Water soluble: vitamin C, vitamin Bs Fat soluble: vitamins A, D, E and K Not synthesised in the body Deficiency leads to a number of diseases REGULATOR NUTRIENTS: MACRO- MINERALS Macro-minerals are required in quantities greater than 100mg/day Approx. Body Content Element RDA/*AI (Healthy Adult) Calcium (Ca) 1400g *1000mg Phosphorous (P) 850g 700mg Potassium (K) 245g *4700mg Sodium (Na) 105g 1500mg Chloride (Cl) 105g - Sulphur (S) 175g Not established Magnesium (Mg) 35g 300mg (Female) 400mg (Male) Source: Advanced Nutrition and Human Metabolism 5th Ed Gropper, Smith and Groff  REGULATOR NUTRIENTS: MICRO-MINERALS Trace/micro-minerals is an essential element of the diet if a dietary deficiency of that mineral results in a suboptimal biological function that is preventable or reversible by physiological amounts of that mineral Approx. Body Content (Healthy Element RDA/*AI Adult) 8mg (male) Iron (Fe) 2.4g 18mg (female) Zinc (Zn) 1.5 – 2.5 g 11mg (male) 8mg (female) Molybdenum (Mo) Unknown 45mcg Selenium (Se) 15mg 55mcg Iodine (I) 15 – 20mg 150mcg 2.3mg (male) Manganese (Mn) 10 – 20mg 1.8mg (female) Source: Advanced Nutrition and Human Metabolism 5th Ed Gropper, Smith and Groff ENERGY YIELDING NUTRIENTS AND METABOLISM VITAMINS AND METABOLISM  ENERGY UNIT: THE CALORIE Amount of energy in food available through digestion Kcal is the unit of energy in nutrition SI unit for energy: kilojoule (kJ) 1 kcal = 4.2 kJ; 1kJ = 0.24 kcal – Amount of heat required to raise the temperature of 1kg (L) water by 10C ENERGY YIELDS kcal/gram kJ/gram Carbohydrate 4.0 16.8 Protein 4.0 16.8 Fat 9.0 37.8 Alcohol 7.0 29.4  BASAL METABOLIC RATE (BMR) or RESTING METABOLIC RATE (RMR) Amount of energy consumed by a person – At rest – Awake – In a thermo-neutral environment – 12 hours after last meal Energy required to carry out normal body functions BMR ≈ 24kcal per kg of weight per day Higher in males, children, people with fever and hyper-thyroidism Lower in females, hypo-thyroidism and starvation Decreases with age  BASAL CALORIC REQUIREMENTS Male = 1800 kcal/day To maintain your basic metabolic rate (BMR) Female = 1300 kcal/day Recommended Dietary Allowances (RDA): – Male = 2,800 kcal/day To carry out all functions in a day – Female = 2,100 kcal/day* – * + 300 during pregnancy + 500 during lactation  DIET-INDUCED THERMOGENESIS (DIT) Thermic effect of food Additional energy expenditure after a meal ≈ 10% BMR Produced by metabolic inter-conversions after a meal Dependent on the composition of the meal Cold exposure and coffee results in thermogenesis  METABOLIC FUELS Metabolic energy: carbohydrates, lipids, proteins and alcohol End products: carbon dioxide, water and urea Energy intake = energy expenditure (1st Law of Thermodynamics) – When energy (kilocalories) input equals energy output, body weight remains constant – When energy input exceeds energy output, body weight increases – When energy output exceeds energy input, body weight decreases IT’S A BALANCING ACT  Exercise TOTAL DAILY ENERGY EXPENDITURE (TDEE) Non-exercise It is the total number of calories you burn in a day Thermic effect Must stay in caloric balance of food TDEE = BMR + non-exercise physical activity + exercise physical activity + DIT Basal metabolic rate 2. Non-exercise physical activity 1. Basal metabolic thermogenesis (NEAT) is 3. Physical activity = calories rate = calories burned the energy expended for burned during exercise by your body carrying everything we do that is not 4. Calories burned out basic functions sleeping, eating or sports-like during digestion like breathing exercise.  DIETARY REFERENCE INTAKES (DRI) Set of reference values for nutrient intakes to be used in assessing and planning diets for healthy populations not individuals 1. The Lower Reference Nutrient Intake (LRNI): Enough for only a small number of people (about 3% of the population who have low needs). It is not enough for most people. 2. Estimated Average Requirement (EAR) The amount which any stated group of people will, on average, need. 3. Recommended Dietary Allowance (RDA) (Also known as Reference Nutrient Intake (RNI) Meets the nutrient needs of the vast majority (97%) of any healthy population Source: UK Dept. of Health 4. Upper Limit (UL) At an intake above the UL the likelihood adverse effects increases  TOTAL PARENTERAL NUTRITION (TPN) Clinical nutrition Practice of feeding a person intravenously, by-passing the gut Nutritional content – Water – Glucose – Salts – Amino acids – Vitamins BODY MASS INDEX (BMI) BMI = body weight (in kg) ÷ height (in meters) squared = kg/m2 Correlates with percentage of body fat and body fat mass Identifies adults at increased risk for morbidity and mortality due to obesity Weight = 72kg, Height = 6 ft = 1.83m BMI = 72/(1.83 X 1.83) = 72/3.35 = 21.5 kg/m2  BMI RANGES BMI