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Basic Human Nutrition Carbohydrates, Dietary Fibre, Lactose intolerance, Milk allergy, Diabetes, Glycaemic index, Artificial sweeteners Lecture 3 Carbohydrates Simple carbohydrates Monosaccharides Disaccharides Complex carbohydrates Polysaccharides Simple Carbohydrates Monosaccharides Glucose Fructose Galactose Disaccharides Maltose Sucrose Lactose Complex Carbohydrates Polysaccharides Glycogen Starches Fibres Glycogen & Starch Molecules Compared (small Segments) Copyright 2005 Wadsworth Group, a division of Thomson Learning Complex Carbohydrates Fibres Cellulose Hemicelluloses Pectins Copyright 2005 Wadsworth Group, a division of Thomson Learning Complex Carbohydrates Fibres Gums and mucilages Lignin Resistant starches Complex Carbohydrates Fibres Soluble fibres Viscous Fermentable Complex Carbohydrates Fibres Insoluble fibres Nonviscous Recommended levels of Fibre: Between 25 to 35 g per day. Ratio of insoluble to soluble of 3 to 1 and should be derived from natural sources in foods rather than from synthetic fiber supplements. The average intake in adults is around 12 to 15 g per day. Fibre health effects Heart disease Diabetes GI health Cancer Weight management Copyright 2005 Wadsworth Group, a division of Thomson Learning Viscous Fibers Copyright 2005 Wadsworth Group, a division of Thomson Learning Nonviscous Fibers Copyright 2005 Wadsworth Group, a division of Thomson Learning Can I have too much fiber? Excess fiber can cause problems: Obstruction of bowel Reduction of the availability of some minerals. Chelating agents link chemically with minerals, iron, zinc, calcium etc, and carry them out of the body. Purified fibers are devoid of other nutrients. Too much bulk in the diet can limit total amount of food consumed—problem for children and elderly. Digestion Mouth Salivary amylase Small intestine Maltase, sucrase, lactase Pancreas Pancreatic amylase Carbohydrate Digestion in the GI Tract Copyright 2005 Wadsworth Group, a division of Thomson Learning Digestion Large intestine Fermentation of viscous fibres Water, gas, short-chain fatty acid production Copyright 2005 Wadsworth Group, a division of Thomson Learning Absorption Copyright 2005 Wadsworth Group, a division of Thomson Learning Lactose Intolerance Symptoms Causes Lactase deficiency Lactose Intolerance Prevalence Symptoms Dietary changes Does not require the elimination of milk/milk products Acidophilus milk Milk Allergy Lactose intolerance often confused with milk allergy. Milk Allergy always due to intolerance to proteins not sugars. Milk allergy – must avoid all sources of milk and milk solids in the diet. Calcium fortified Soya milk and juice and calcium supplements can replace calcium lost from dairy products. Glucose in the Body Energy Glycoproteins Glycolipids Body’s use of glucose In liver fructose and galactose are converted to glucose. The liver uses a small amount of glucose for its activities then converts the excess into glycogen – glycogenesis. Gycogen stores Glycogen makes up about 10% of weight of liver or 100g. Muscles hold about 325 g of glycogen. Only about 15 to 20 g of CHO remains unstored and circulates as blood glucose. Reconversion of glycogen to glucose called glycogenolysis. Carbohydrate Metabolism Making glucose from protein Gluconeogenesis Process rapidly depletes muscle CHO is essential Protein-sparing action of carbohydrates Carbohydrate Metabolism Converting glucose to fat Fat cannot be converted to glucose Energetically expensive –glucose must combine with fragments before can be used as energy. Without CHO-ketosis develops Carbohydrate Metabolism Making ketone bodies from fat fragments Ketosis Acid-base balance Dehydration 100g digestible CHO/day needed to spare protein and avoid ketosis Regulation of blood glucose After a meal, blood glucose rises. Hormone insulin released to assist uptake of glucose by tissues. Muscle and liver store the glucose as glycogen. (Excess stored as fat) When blood sugar drops, pancreas secretes hormone glucagon. Regulation of blood sugar continued Glucagon stimulates conversion of glycogen in liver to glucose (glyconeogenolysis). Blood sugar rises. Stress hormone Epinephrine does the same thing when body in danger. Blood sugar is tightly regulated by the liver and insulin to a range called normoglycemic. Copyright 2005 Wadsworth Group, a division of Thomson Learning Maintaining Blood Glucose Homeostasis Glycaemic Effect Some foods raise blood sugar more than others Measured by how fast and how high the blood sugar rises after a standardized portion of 100g of a food. Fibre content, particularly soluble, cooking methods and mixed foods affect glycaemic index of a food. E.g., ice cream lower than potatoes. Baked potato lower than mashed potato. Glycaemic effect important to people with diabetes. Constancy of Blood Glucose Glycaemic response Glycaemic index Copyright 2005 Wadsworth Group, a division of Thomson Learning Constancy of Blood Glucose Diabetes Type 1 diabetes 10-20% of all cases Failure of insulin production Cause: viral, genetics, disordered immune system, other diseases, environmental toxins. Type 2 diabetes Obesity Type 2 diabetes; NIDDM 90% of all cases Characterized by insulin resistance of body’s cells including fat cells. Cells take up glucose too slowly; blood sugar rises. Insulin also rises. Pancreas loses supply of insulin and may require supplementation with exogenous insulin. Causes of type 2 diabetes Genetics Aging Excess body fat Excess alcohol Uncontrolled diabetes… High blood sugars destroy small capillaries feeding organs. Can lead to: Blindness Kidney disease Amputation of limbs (gangrene) Heart Disease, strokes Decreased resistance to infection Nerve damage Diabetes is diagnosed.. Fasting Blood test or glucose tolerance test. Glucose tolerance test: a 100g of glucose in a sugary drink taken after fasting overnight. Blood sugar is measured at set intervals to see how blood sugar responds. Management of diabetes… Diet and/or oral hypoglycaemic drugs or insulin. Diet: high in complex CHO, moderate in simple sugars, high in fibre, low in saturated fat, moderate in protein. Exercise to regulate blood sugar and weight. Hypoglycaemia A symptom-low blood sugar Postprandial hypoglycaemia – low sugars after a meal. Fasting hypoglycaemia A blood test required to confirm low blood sugar and observation of symptoms. Hypoglycaemia continued Symptoms: headache, mental dullness, fatigue, confusion, amnesia, seizures and unconsciousness. Rare causes: pancreatic cancer, infection of liver (hepatitis), advanced alcohol-induced liver disease. A few people are very sensitive to insulin (may be pre-diabetic). Hypoglycaemia continued Diet consists of: regular small meals, high in complex CHO and fiber combined with protein to delay absorption of CHO and slow release of glucose into blood stream. Sugars Added sugars Sucrose, invert sugar, corn syrups, etc. Sugars Health effects of sugars Nutrient deficiencies Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning Sugars Health effects of sugars Dental caries Dental plaque Copyright 2005 Wadsworth Group, a division of Thomson Learning Accusations Against Sugars Sugar causes obesity Sugar causes heart disease Copyright 2005 Wadsworth Group, a division of Thomson Learning Accusations Against Sugars Sugar causes hyperactivity in children Sugar causes type 2 diabetes DRI for CHO RDA for carbohydrate 130 g/day 45% - 65% total daily energy intake Daily Value: 300 g/day No more than 25% of total daily energy intake from simple sugars Artificial sweeteners Two types: sugar alcohols and noncaloric sweetners. Sugar alcohols: sorbitol, mannitol, Isomalt, xylitol widely used in foods. Provide 2 to 4 calories per gram. Do not cause dental caries. May cause diarrhea in large quanitities. Copyright 2005 Wadsworth Group, a division of Thomson Learning Copyright 2005 Wadsworth Group, a division of Thomson Learning Artificial sweeteners Saccharine,Cyclamate and cancer Aspartame and PKU Copyright 2005 Wadsworth Group, a division of Thomson Learning Do artificial sweeteners help with weight control? Artificial sweeteners can assist with weight control. Beverages, particularly pop, coffee/tea, contribute greatly to total calories. Sugar –free is therefore beneficial. Sugar-free snacks, pastries, cakes are less popular which offsets benefit of artificial sweetener.