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Introduction to the Science of Nutrition

Introduction to the Science of Nutrition. NS 332 9/4/09. Nutrition: the process by which a living organism assimilates food and uses it for growth and maintenance of tissues. Nutrients- components of food: Provide energy Provide structural materials

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Introduction to the Science of Nutrition

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  1. Introduction to the Science of Nutrition NS 332 9/4/09

  2. Nutrition: the process by which a living organism assimilates food and uses it for growth and maintenance of tissues Nutrients- components of food: • Provide energy • Provide structural materials • Provide regulatory agents that support cell growth, maintenance, and repair of tissues • May reduce the risk of certain diseases

  3. Definitions - Homeostasis • Food • Diet • Organic (vitamins) • Inorganic (minerals) • Essential nutrient (3 criteria) • Phytochemical: non-essential, but may optimize nutritional status

  4. An Abbreviated History of Nutrition • 1747: Dr. Lind discovered that limes prevented scurvy • 1770: Levoisier documented that food and oxygen in the body produces in heat and water • 1897: Eijkman discovered that brown rice as opposed to white rice prevented Beri-Beri • 1912: McCollum discovered vitamin A

  5. Current Nutrition • Determine: • Optimal levels of nutrients that lead to optimal health • The role of phytochemicals- non essential but may lead to greater health • Optimal nutrition for individuals

  6. Classes of Nutrients • Macronutrients - Carbohydrate - Lipid - Protein - Water • Micronutrients • Vitamins • Minerals

  7. Classes of Nutrients: Carbohydrates - Main source of energy - Fruits, vegetables, grains - Composed of carbon (C), hydrogen (H), and oxygen (0) - Sugars, starches, and fiber

  8. Classes of Nutrients: Lipids - Energy source, component of cell walls - Oils, fats, nuts, fatty fish, avocado - C, H, O, sometimes phosphorous (P) and nitrogen (N) - Saturated, unsaturated, essential, and trans fats

  9. Classes of Nutrients: Proteins - Main structural material in the body and nitrogen source - Meat, poultry, fish, soy based products, dairy, legumes, grains - C,H,O,N,S - Composed of amino acids - Complete vs incomplete

  10. Classes of Nutrients: Water - Essential for all life • Functions as a solvent, a lubricant, and a medium for transporting nutrients into cells • Human body is 60% water

  11. Classes of Nutrients Vitamins - Organic compounds (13 known essential) - Necessary for specific biochemical reactions in cells - Water or fat soluble Minerals - Inorganic elements (16 known essential) - Key roles in the nervous and skeletal system as well as necessary for biochemical reactions in cells - Major and trace

  12. Nutrient Composition of the Body versus Food

  13. Energy: the Capacity to do Work • Without energy, we couldn’t move or breathe • Food is a form of chemical energy measured in calories • Calorie is a unit of heat energy: • 1 kilocalorie = 1000 calories • 1 kcal = the amount of energy necessary to increase the temperature of 1 kg of water 1°C (a relatively small amt of heat) • Food is more accurately expressed in kcal • Food labels use ‘calories’ but they really mean kcal

  14. Energy in Biological Systems: ATP • Without energy we couldn’t move or breathe • Adenosine triphosphate • Energy from food is captured as ATP through metabolism • ATP drives any biological reaction that requires energy

  15. How do we know how much energy (calories) is in the food we eat? • 4-9-4 rule: • Carbohydrate = 4 kcal/gram • Fat = 9 kcal/gram • Protein = 4 kcal/gram • 1 medium banana • carbs 30g x 4 kcal/g = 120 kcal • fat 0.5g x 9 kcal/g = 5 kcal • protein 1.0g x 4 kcal/g = 4 kcal • Total = 129 kcal

  16. Daily intake of Macronutrients Carbs: 300 g x 4 kcal/g = 1,200 kcal (62% total) Fat: 50 g x 9 kcal/g = 450 kcal (23% total) Protein: 70g x 4kcal/g = 280 kcal (15% total) 1,930 total kcal

  17. Nutrient Density • A ratio of vitamin and mineral content of a food to its energy content 5%-- Energy-------4% 0%-- Protein------18% 0%-- Vitamin A---21% 0%-- Vitamin C---0% 0%-- Thiamine---10% 0%-- Riboflavin---44% 0%-- Niacin--------2% 0%-- Calcium------24% 0%-- Iron-----------0% 8 oz 8 oz (shown as a %RDA for adolescent females)

  18. Energy Density • A ratio of the energy content of a food (kcal) with its weight (g)

  19. Nutritional Assessment • Anthropometric measurements • Biochemical testing • Clinical Assessment • Diet history

  20. Malnutrition • Undernutrition • Biochemical lesion • Clinical lesion • Primary deficiency • Secondary deficiency

  21. Malnutrition • Overnutrition • Obesity – excess of energy • Excess of micronutrients

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