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 Glycaemic Carbohydrates • Glycaemic carbohydrates • Regulating blood glucose • Glycaemic Index Carbohydrate Digestion Glycaemic...

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 Glycaemic Carbohydrates • Glycaemic carbohydrates • Regulating blood glucose • Glycaemic Index Carbohydrate Digestion Glycaemic Non-glycaemic Starch Fibre Salivary amylase Mechanical action crushes and tears Stomach acid inactivates amylase Not digested, delays gastric emptying Pancreatic amylase Small glucose polymers and disaccharides Not digested in small intestine Enzymes on surface of intestinal cells Maltose, sucrose, lactose Bacterial enzymes digest fibre in the large 3 intestine Regulating Blood Glucose • In healthy people blood glucose concentrations are regulated within a fairly narrow range • Blood glucose depends on food and hormones • Insulin stimulates increased uptake of glucose • Glucagon stimulates glycogen breakdown in the liver Insulin and Glucagon Regulating Blood Glucose Insulin and Cellular Uptake of Glucose Muscle and adipose tissue Brain and liver Insulin Promotes Energy Storage Glucagon Promotes Mobilisation of Stored Energy Diabetes Mellitus • Type I diabetes – Pancreas fails to produce enough insulin – Requires insulin injections (implanted pumps) – Glucose in urine, weight loss • Type II diabetes – Insulin insensitivity/resistance – Associated with lifestyle (obesity) Blood Glucose Concentrations For healthy people, normal fasting blood glucose levels are between 4.0 to 5.4 mmol/L Plasma glucose test Normal Fasting Prediabetes Below 5.5 mmol/L 5.5 to 6.9 mmol/L Diabetes 7.0 mmol/L or more 2 hour post-prandial Below 7.8 mmol/L 7.8 to 11.0 mmol/L 11.1 mmol/L or more Dietary Management of Blood Glucose • Glycaemic index (GI) introduced to aid dietary management of diabetes. • Means to quantitatively compare blood glucose response to different carbohydrate foods. Glycaemic Response GI >70 GI <55 Gropper, Smith 2013 High, Medium and Low GI Foods. Quiz • On a scale of 1 to 5, how difficult was this lecture? • What slides were most difficult? 15 Reading • 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 • McGuire M, Beerman KA: Nutritional Sciences: From Fundamentals to Food. 3rd ed. Belmont, CA: Wadsworth; 2013. Chapter 4