YR1 Lecture 1H - Macronutrients - Carbohydrates, Fats and Proteins -Victoria Mansour - 1H 2019 (1).pdf

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COPYRIGHT COMMONWEALTH OF AUSTRALIA Copyright Regulations 1969 WARNING This material has been reproduced and communicated to you by or on behalf of University of Western Sydney pursuant to Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice. Learning Objectives  Describe the following macronutrients: carbohydrates, fats and proteins  Describe how different macronutrients are digested  Discuss how macronutrients are important for body function and their impact on health  Describe cholesterol and discuss its transport http://personallevelfitness.com/wp-content/uploads/2015/08/Carbsfatprotein-600x450.jpg Carbohydrates  The most abundant organic molecule  Dietary carbohydrate provides a fast source of energy to cells, especially to those whole rely on glucose as the primary energy source  Glucose can provide 4.1 kcal/g  Can be linked to other biological molecules to assist other roles in the body  Lipids  Proteins  Carbohydrates can be composed of:  Monosaccharides & Oligosaccharides  Simple sugars  Polysaccharides  Starch  Dietary fibre http://shawnutrition.com.au/controversial-carbohydrates/ Carbohydrates - Monosaccharides  Sugars can be directly absorbed in the GIT as monosaccharides  Not a problem for simple sugars (naturally occurring or end-product of digestion)  For disaccharide sugars digestion is required  Lactose by lactase  Maltose - glucoamylase  Sucrose – sucrase-isomaltase Mostly found naturally in fruits, vegetables, juices Not found naturally as a monosaccharide Mostly found naturally in fruits, vegetables, honey Lactose – natural sugar in milk and dairy Maltose – mostly obtained by digestion of starchy foods Sucrose – sugarcane, sugar, fruits and some vegetables Pictures sourced from Garret and Grisham, Biochemistry 4th edition (2010) Carbohydrates – Polysaccharides  Starch is the energy store for plant  A complex carbohydrate  Found in grains and grain products, seeds, roots, potatoes and other plants  Exists as    α-amylose (~10-30%) amylopectin (90-70%) Both degraded by α-amylase  Maltose and Matriose degraded by glucoamylase and sucrase-isomaltase  α-limit dextrins however only degraded by sucrase-isomaltase Maltriose Maltose α-limit dextrin Pictures sourced and modified from Garret and Grisham, Biochemistry 4 th edition (2010) Carbohydrates – Polysaccharides  Dietary fibre  Complex carbohydrate  The indigestible portion of plants  Cannot be absorbed  Two forms exist  Soluble  Insoluble  Can assist with  Laxation (1)  Reduction in blood cholesterol (1)  Modulation of blood glucose (1) (1) https://www.nrv.gov.au/nutrients/dietary-fibre Carbohydrates – Low GI vs High GI  Low GI foods  slowly digested, absorbed and metabolised  slower rise in blood glucose  Important for  Weight management  Diabetes  Pregnancy https://www.gisymbol.com/about-glycemic-index/ Proteins  Proteins are polymers of amino acids (AA)  Dietary protein is a rich source of nitrogen and essential amino acids  Carbs are the preferred energy source, proteins provide ~4.3 kcal/g  Digestion of protein is accomplished by luminal, brush border, and cytosolic peptidases to hydrolyse proteins to oligopeptides, dipeptides and AAs http://www.ebi.ac.uk/training/online/sites/ebi.ac.uk.training.online/files/user/71/images/figure1.png Proteins The body needs protein  Required for biological processes The body does not store excess protein, but it can be allocated to     Energy Protein synthesis Protein metabolism Storage Fats (lipids)  Fats can be used by many tissues as fuel  Fats are the most concentrated form of energy  9.4 kcal/g  Dietary is fat is needed   Essential fats Fat-soluble vitamins  Dietary fat mostly consists of:   Mostly Triacylglycerols (TAGs) aka triglycerides (TG) Phospholipids & cholesterol  Digestion of lipids is accomplished by    Lipases Cholesterol esterase Phospholipase aided by bile http://healthimpactnews.com/wp-content/uploads/sites/2/2014/02/fats-and-meats-lg-1.jpg Fats (Lipids) – Triacylglycerols (TAGs)  Typical structure is 3 FAs attached to a glycerol molecule  Can be the same or different  Dietary Fats we obtain from plant and animal sources are usually in the form of TAGs (~90%)  Usually a mixture of the 2 types Garret and Grisham, Biochemistry 4th edition (2010) Fats (lipids) – Fatty acids (FAs)  Monounsaturated and polyunsaturated FAs  Presence of double bonds  MUFAs - Can be found in avocado, and nuts (almonds, cashews), canola or olive spreads and oils  PUFAs - Includes Omega-3 and Omega-6 fatty acids  Can be found in fish, seafood, polyunsaturated margarines, vegetable oils (sunflower, corn or soy), nuts (walnuts ,Brazil) and seeds  Saturated and Trans FAs  Carbons saturated with hydrogen  Saturated - Can be found in fatty cuts of meat and full-fat dairy products, “fast food”, butter  Trans FAs - Primarily found in processed foods https://whetyourwoman.files.wordpress.com/2013/03/saturated_fats-vs-unsaturated_fats.jpg Fats (Lipids) – Phospholipids and Cholesterol  Generally phospholipids consist of:  Cholesterol   Hydrophilic head – phosphate group Glycerol  Hydrophobic tail - FAs   Known as a sterol  alcohol + steroid Rigid fused ring structure  Both are    Made endogenously Components of membranes Important components of bile  Cholesterol specifically   Precursor for steroid hormones Component of lipoproteins Garret and Grisham, Biochemistry 4th edition (2010) Fat & Cholesterol transport  Lets look at some players first  Chylomicrons  Produced by enterocytes  Chylomicron remnants  higher cholesterol content to TAG  Very Low Density Lipoproteins (VLDL)  Produced by the liver  Intermediate Density Lipoproteins (IDL)  Derived from VLDL breakdown  LDLs  Derived from IDL breakdown  High cholesterol content  HDLs  Empty shells produced by the liver Marieb, E. Human Anatomy & Physiology (7th Edition) (2006) Fat & Cholesterol transport LDL IDL Dietary Fat Intestines Chylomicrons Tissues Chylomicron remnants Bile HDL Liver VLDL Macronutrients and Energy Metabolism  Macronutrient digestion  Carbohydrates  Initiated in the mouth & resumes for completion in small intestine  Salivary and pancreatic amylases  Lactase, sucrase-isomaltase, glucoamylase (brush border enzymes)  Proteins  10-15% initiated by pepsin in stomach & remainder in small intestine  Luminal, brush border, and cytosolic peptidases  Fats  15% initiated in stomach & remainder in small intestine  Lipases (gastric, pancreatic & milk), phospholipases, cholesterol esterase Garret and Grisham, Biochemistry 4th edition (2010); Boron and Boulpaep, Medical Physiology 2nd edition (2012) Clinical relevance: Nutrition and Health  Some health issues can be attributed to genetic, diet, illness and other causes  Healthy eating  Know your serves & calorie intake    Age, gender, demand on body Reading food labels Moderation http://media3.s-nbcnews.com/j/newscms/2016_20/1544486/160520-fda-label-mn-0945_cf73c17c5c3131a24a5fd64da199fc0b.nbcnews-ux-2880-1000.jpg accessed 10.4.2018 Clinical relevance: Nutrition and Health  Healthy eating  Know your serves and calorie intake    Age, gender, demand on body Reading food labels Moderation  Obesity    Genetic & Lifestyle factors Hormonal Medications https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3513909/pdf/vhrm-8-651.pdf http://braisedanatomy.com/wp-content/uploads/2012/03/Lactose-Intolerance.jpg https://www.eatforhealth.gov.au/sites/default/files/content/The%20Guidelines/n55a_australian_dietary_guidelines_summary_131014_1.pdf Clinical relevance: Nutrition and Health  Healthy eating  Know your serves and calorie intake    Age, gender, demand on body Reading food labels Moderation  Obesity    Genetic & Lifestyle factors Hormonal Medications  Diabetes   Genetic & Lifestyle factors High circulating blood sugars, high insulin, active gluconeogenesis & glycogenolysis Clinical relevance: Nutrition and Health  Some health issues can be attributed to genetic, diet, illness and other causes  Hypercholesterolemia   Most commonly lifestyle causes- diet rich in fatty foods, lack of exercise Familial hypercholesterolemia https://www.youtube.com/watch?v=PbfuLpXoI5g      Food intolerance Lactose   cannot breakdown lactose Common cause     Commonly caused by mutations in the LDLR gene and other genes Reduces the no. LDL liver receptors or disrupts function High LDL and cholesterol levels  high risk of coronary artery disease lactase dysfunction Rare congenital lactase deficiency GIT injury Gluten   Autoimmune response Inflammation of GIT https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3513909/pdf/vhrm-8-651.pdf http://braisedanatomy.com/wp-content/uploads/2012/03/Lactose-Intolerance.jpg Summary  Dietary macronutrients are essential for proper cell, tissue and body function  They include    Carbohydrates Protein Fats  Once broken down into monomers can be used for energy  Fats > Protein = Carbohydrates  Food macronutrient composition varies  Excess consumption of dietary macronutrients can have a significant effect on ones health  Thus, essential we have a balanced diet  Lifestyle & Genetic factors can be factors affecting health and macronutrient consumption Questions Links and Resources  Garret and Grisham, Biochemistry 4th edition (2010)  Boron and Boulpaep, Medical Physiology 2nd edition (2012)  http://www.abs.gov.au/Health-Conditions-and-Risk-Factors  https://www.eatforhealth.gov.au/sites/default/files/content/The%20Guideli nes/n55a_australian_dietary_guidelines_summary_131014_1.pdf (pages 4144 – serves)  http://healthyweightweek.com.au/understanding-food-labels/  https://www.gisymbol.com/top-tips-to-go-low-gi/  https://www.who.int/nutrition/5keyshealthydiet_banner.pdf Thank you  Lecture feedback Contact Details Associate Lecturer Victoria Mansour Medical Education Unit Year 1 PBL Coordinator PBL tutor Curriculum Roadmap Coordinator Western Sydney University [email protected] Phone 02 46203751 Office 30.3.14 Available Mon, Tues, Thurs & Fri