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Chapter 5

Chapter 5 - Basic Nutrition.docx

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Health Sciences
Health Sciences 1001A/B
Shauna Burke

Chapter Five: Nutrition Basics Diet and Nutrition: - An area in which you have high control - Provides body with nutrients required to produce energy, repair damaged tissue, promote tissue growth, regulate physiological processes Choosing a healthy diet involves: 1. Knowing which nutrients are necessary and in which amounts 2. Translating those requirements into a diet consisting of foods you like and that are available / affordable Nutritional Requirements: - Body requires proteins, fats, carbohydrates, minerals and water (essential nutrients) - Essential = must get substances from food because body is unable to manufacture them (or not enough to meet physiological needs) - Body obtains nutrients through digestion - Energy in food expressed in kilocalories = scientific expression of energy value in a food Three classes of essential nutrients supply energy: 1. Fat = 9 calories per gram 2. Protein = 4 calories per gram 3. Carbohydrates = 4 calories per gram - If all types of calories > energy expenditure = converted to fat and stored in the body Protein: - Found in every living cell - Promotes growth and maintenance of body tissue - Primary component of muscles and connective tissue - Form important parts of blood, enzymes, some hormones, and cell membranes - Composed of chains on amino acids - When an essential amino acid is missing from diet, it will result in deficiencies - Foods that contain 9 essential amino acids are complete proteins (milk, meat, fish, poultry, cheese, eggs, soy beans and tofu) - Foods that contain less than 9 essential amino acids are known as incomplete proteins (veggies, grains, legumes, nuts) - Essential amino acids can be obtained from combinations of incomplete protein sources (red beans and rice) Proteins in Weight Management: - Consumption of protein with carbohydrates delays carbohydrate absorption and attenuates the body’s insulin response - Dietary intakes with less than 15% of energy from proteins can result in muscle loss - Appears to be no difference in lean body mass gains between 15% and 25% protein diets - High protein diets do not lead to weight loss unless calories are also reduced Fats (lipids): - Provide a concentrated form of energy - Give some foods a pleasing taste, texture - Help absorption of fat-soluble vitamins (A, D, E, K) - Insulates our bodies to help retain heat - Provides a protective cushion for internal organs and bones - Viable fats represent only roughly 40% of the fat we consume Dietary fats consist of a combination of 3 forms of fat based on chemical composition: 1. Saturated - Typically solid at room temperature - Found naturally in animal products 2. Monosaturated - Typically liquid at room temperature - Usually from plant sources (olive and canola oil) 3. Polyunsaturated - Typically liquid at room temperature - Usually from plant sources (soybean and corn oil) - Includes two essential fatty acids Trans fatty acids = unsaturated fatty acids - Used to increase stability of oil so it can be reused for deep frying, to increase texture of foods and to increase shelf life of foods - Also found in small amounts in meat and mild - Leading sources of trans fats are deep-fried foods, baked and snack foods, and stick margarine ** The softer (or more liquid) a fat is, the less saturated and trans fat it is likely to contain Fats (lipids) and Cholesterol - Low density lipoprotein (LDL) cholesterol = “bad cholesterol” - Saturated and trans fatty acids increase blood levels - High density lipoproteins (HDL) cholesterol = “good cholesterol” - Monosaturated fatty acids may increase blood levels - Trans fatty acids may decrease blood levels in large amounts Fats in Weight Management - Type of fat (vs. presence of fat) seems to contribute most to CV disease - Trans fat consistently associated with higher risk coronary heart disease - Unsaturated fats appear to be most beneficial in terms of cardioprotection ** Choose unsaturated fats instead of saturated and trans fats to decrease risks of heart disease Carbohydrates: - Various combinations of sugar units (saccharides) - Used primarily for energy Occur in three forms: 1. Monosaccharides (one unit) - Glucose (blood sugar) 2. Disaccharides (two units) - Sucrose (table sugar) 3. Polysccharides (more than two units) - Starches Starches are among the most important sources of dietary carbohydrates - Found primarily in grains, legumes, potatoes and yams - Unrefined (whole grain) complex carbohydrates are high in fibre, vitamins, minerals, and other compounds - Also take longer to chew and digest, enter bloodstream slower Carbohydrates in Weight Management: - Low carbohydrate diets (e.g. Atkins) contain < 30g of carbohydrates per day (adherence is difficult with < 35% of energy from carbohydrates) - People can lose more weight at the start of Atkins type diets by using up their glycogen stores (stored with roughly 10lbs of water weight) - Weight loss: low carbohydrates and low fat diets not significantly different after 12 or 24 months Type of carbohydrates in diets is important: - Complex whole grain carbohydrates high in fibre associated with increased satiety compared to refined carbohydrates (sugar or white bread) which produce a rapid and sharp increase in insulin Fibre: - Non-digestible carbohydrates provided by plants - Passes through the intestinal tract and provides the bulk of feces in large intestine - Can help decrease risk of type two di
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