Human Nutrition 1: Understanding Nutrients PDF

HNUT10010 HNUT10020 Human Nutrition 1: Understanding Nutrients Aifric O’Sullivan BSc, MSc, PhD UCD Institute of Food and Health School of Agriculture and Food Science 1 Carbohydrate Biochemistry • • • • What are carbohydrates? Classification Structures Properties 2 Carbohydrates 3 Classifi...

HNUT10010 HNUT10020 Human Nutrition 1: Understanding Nutrients Aifric O’Sullivan BSc, MSc, PhD UCD Institute of Food and Health School of Agriculture and Food Science 1 Carbohydrate Biochemistry • • • • What are carbohydrates? Classification Structures Properties 2 Carbohydrates 3 Classification • Chemistry – Monosaccharide – Disaccharide – Oligosaccharide – Polysaccharide • Nutrition – Glycaemic – Non-glycaemic 4 Monosaccharide  Glucose – C H O 6 12 6  Fructose – C H O 6 12 6  Galactose – C H O 6 12 6  Each has a unique atomic arrangement, giving them different biochemical characteristics. 5 Atoms 6 Monosaccharide • • • • Exist in the cyclic form 6 carbons called a hexose Aldehyde or ketone functional group Chiral compounds 7 Monosaccharide Aldehyde Ketone There are 4 chiral carbons in glucose (carbons numbered 2-5 in the diagram) The highest numbered chiral carbon determines whether it is an L or D stereoisomer. 8 Disaccharides Disaccharides are 2 monosaccharides combined. Glycosidic bond 9 Disaccharides Maltose 2 glucose (1-4) glycosidic bond Beer Lactose Galactose + glucose β(1-4) glycosidic bond Milk Sucrose Fructose + glucose (1-2) glycosidic bond* Table sugar 10 Oligosaccharides 3-9 monosaccharides • Raffinose: galactose, fructose, and glucose – beans, cabbage, brussels sprouts, broccoli, asparagus • Stachyose: galactose, galactose, glucose, fructose – green beans, soybeans • Fructo-oligosaccharides: fructose – Onions, artichoke, asparagus • Galacto-oligosaccharides: galactose – Soybeans, synthesised from lactose • Beneficial bacteria “pre-biotics” 11 Polysaccharides  Starch is the storage form of energy in plants (different types of starch)  Fibre/ Non-starch polysaccharides provide structure in plants (different types of fibre)  Glycogen is the storage form of glucose in the body 12 Starches: Amylose and Amylopectin Gropper, Smith 2013 13 Non-starch Polysaccharides (Fibre) • Resistant to the digestive enzyme -amylase 14 Glycogen Liver = 80-100 g Muscle = 300-500 g (↑athlete) 15 Chemist’s View of Carbohydrates Match these With these a) Complex carbohydrates b) Sucrose c) Galactose d) Lactose e) Fructose f) Maltose g) Glucose a) Monosaccharide b) Polysaccharide c) Disaccharide Answer: ab bc ca dc ea fc ga Explanation: “Mono”=one “Di”=two “Saccharide”=sugar 16 Quiz • On a scale of 1 to 5, how difficult was this lecture? • What slides were most difficult? 17 Reading • Lanham-New S, Macdonald IA, Roche Hm, eds. Nutrition and Metabolism. 2nd ed: Wiley-Blackwell, 2011. Chapter 10 • Gibney M, Lanham-New S, Cassidy A, Vorster H, eds. Introduction to Human Nutrition. 2nd ed: WileyBlackwell, 2009. Chapter 5 • Gropper SS, Smith JL. Advanced Nutrition and Human Metabolism, International Edition 6th ed: Wadsworth Cenage Learning, 2013. Chapter 3 & 4 18