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Chapter 1&2

CHAPTER 1 & 2.docx

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NUTR 2050
Jess Haines

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Week 1 & 2 - Chapter 1: Nutrition Basics • Nutrition = the study of foods, their nutrients and other chemical constituents and the effect of food constituents on health • Nutrition is an interdisciplinary science • Recommendations for public knowledge as new knowledge about nutrition and health is gained • Everyone requires the same nutrients just different amounts • Nutritional status at one life stage affects health status for other health cycles Principles of the Science of Nutrition • the need for food is part of Maslow’s hierarchy of needs 1. Food is a basic need of humans -food security: enough food to meet all needs at all times -food insecurity: availability of safe, nutritious foods or ability to acquire them is limited 2. Foods provide energy (calories), nutrients, and other substances needed for growth and health 3. Health problems related to nutrition originate within cells 4. Poor nutrition can result from both inadequate and excessive levels of nutrient intake 5. Humans have adaptive mechanisms for managing fluctuations in food intake 6. Malnutrition can result from poor diets and from disease states, genetic factors combinations of these causes 7. Some groups of people are at higher risk of becoming inadequately nourished than others 8. Poor nutrition can influence the development of certain chronic diseases 9. Adequacy, variety, and balance are key characteristics of a healthy diet 10. There are no ‘good’ or ‘bad’ foods Essential & Nonessential Nutrients • Nutrients the body cannot manufacture: -carbohydrates -essential amino acids -water -linolenic and alpha linolenic acid -vitamins and minerals • Requirements for amount of nutrients caries based on: -age and gender -body size and genetics -illness and medication -lifestyle habits -pregnancy and lactation • non essential nutrients are present in foods and used by the body but not necessary in our daily diets: -cholesterol -creatine -glucose -chemical substances in plants Dietary Intake Standards • don’t take into account all factors that influence nutrient needs but for the major ones (age, gender, growth, pregnancy) • DRI: general term for nutrient intake standards for healthy people • RDA: recommended dietary allowances, levels of essential nutrient intakes judged to be adequate while decreasing the risk of certain chronic diseases • AI: adequate intakes, tentative RDAs based on less conclusive scientific information • EAR: estimated average requirements, nutrient intake values that are estimated to meet the requirements of half the healthy individuals in a group -used to assess the adequacy of intakes of population groups • UL: tolerable upper intake levels, represent total daily levels of nutrient intake from foods, fortified foods, supplements that should not be exceeded • Daily values: scientifically agreed standards for daily intakes of nutrients from the diet developed for use on nutrition labels • People should aim for nutrient intakes that approximate the RDAs or AI levels Carbohydrates • Used by the body mainly as a source of readily available energy • Consist of: -simple sugars (mono and di –saccharides) -complex sugars (polysaccharides) -dietary sources of fibre -alcohol sugars • Alcohol  Ethanol is considered to be part of this nutrient category • Most common monosaccharides: -glucose: aka blood sugar, dextrose table sugar -fructose: aka fruit sugar malt sugar -galactose: aka milk sugar milk sugar • Most common disaccharides (2 monomsaccharides): -sucrose = glucose + fructose -maltose = glucose + glucose -lactose = glucose + galactose • Polysaccharides include: -starches: plant form of stored carbohydrate -glycogen (animal form of stored carbohydrate -most types of fibre • Each type of simple and complex carbohydrate provides 4 calories/gram, except fibre • Dietary fibre provides 2 calories/gram on average -even though it can’t be broken down by the human digestive enzymes • Bacteria in the large intestine excrete fatty acids as a waste product of (some) fibre digestions -fatty acids are absorbed and stored as a source of energy • Main function of fibre is to provide ‘bulk’ for normal elimination • High fibre diets reduce rate of glucose absorption and helps prevent cardiovascular disease and some types of cancers • Common forms of alcohol sugars are: -xylitol -mannitol -sorbitol • Alcohol consumed as ethanol, is part of the carbohydrate family because it is similar in structure to glucose -its a product of fermentation of sugar with yeast Glycemic Index of Carbohydrates & Carbohydrates In Foods • Insulin resistance: condition where cell membranes have a reduced sensitivity to insulin -more insulin than normal is required to transport a given amount of glucose to cells • Type 2 diabetes: disease characterized by high blood sugar levels due to body’s inability to use insulin normally, to produce enough insulin, or both • Glycemic Index: carbohydrates (and food containing) are now being classified by the extent to which they increase blood glucose levels • Carbohydrates digested and absorbed quickly have a high glycemic index and raise blood glucose levels • Diets with low glycemic index carbohydrates help people with diabetes: -reduce elevated levels of blood cholesterol and triglecerides -increase levels of beneficial HDL cholesterol -decrease risk of developing type 2 diabetes -some cancers and heart disease • Recommended intake levels is based on their contribution to total energy intake • Carbohydrates are widely distributed in plant foods -milk is only important animal source of carbohydrate (lactose) Protein • Protein provides the body with amino acids used to build and maintain tissues • Protein provides 4 calories/gram and used as a source of energy • There are 9 essential amino acids LIST ON PAGE 3 • Non essential amino acids can be obtained from food and the body can manufacture it • Foods of high protein qua
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