1 / 75

Introduction to Human Nutrition

Introduction to Human Nutrition. the science of foods and the nutrients they contain. The food choices you make daily have a cumulative impact on your health. Poor food choices lead to chronic disease. Diet: the food one consumes. What is Food ?.

Download Presentation

Introduction to Human Nutrition

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Introduction to Human Nutrition the science of foods and the nutrients they contain

  2. The food choices you make daily have a cumulative impact on your health. Poor food choices lead to chronic disease. Diet:the food one consumes

  3. What is Food? • Foodcontain nutrients and are derived from plant or animal sources • Nutrients are used by the body to provide energy and to support growth, maintenance and repair of body tissues

  4. Functional Foods • Functional foods contain substances that provide health benefits beyond those of their nutrients • May be a natural functional food or as a result of additives • Tomatoes – contain lycopene • Orange juice with calcium

  5. 1. Carbohydrates 2. Lipids (fats) 3. Proteins 4. Vitamins 5. Minerals 6. Water The 6 Classes of Nutrients

  6. Body Composition

  7. Classification of Nutrients • Organic or inorganic • Essential or nonessential • Macronutrient or micronutrient • Energy yielding or not

  8. Essential Nutrients • Nutrients the body either cannot make or cannot make enough of to meet its needs • Must be obtained from foods • Examples: • Vitamins • Calcium, iron, and other minerals • Some of the amino acids

  9. NonessentailNutrients • Body can make from other nutrients ingested • Examples: • Cholesterol • Some amino acids

  10. Classifying Nutrients by Composition • Organic nutrients - contain carbon • Carbohydrates • Lipids • Proteins • Vitamins • Inorganic nutrients - do not contain carbon • Minerals • Water

  11. Quantity Needed • Macronutrients: need in relatively large amounts • Carbohydrates, lipids, proteins • Micronutrients: need in relatively small amounts • All other nutrients

  12. 3 Energy Yielding Nutrients • Carbohydrates • Fats (lipids) • Proteins • Where does the energy come from?

  13. A little more on energy • Measure energy in kilocalories in U.S. • What most think of as a “calorie” is really a kilocalorie • Kcal = amount of energy needed to raise the temperature of 1 kg of water by 10C • Measure energy in kilojoules (kJ) in most other countries

  14. Energy-Yielding Nutrients

  15. Carbohydrates • C H O • 4 kcal/gram • Body’s primary source of energy • Use as glucose • Brain’s only source of energy • Stores are limited ~12-24 hours (in liver and muscle)

  16. Carbohydrates • Energy Metabolism • Glucose is the fuel used by cells to make ATP • Neurons and RBCs rely almost entirely upon glucose • Excess glucose is converted to glycogen or fat and stored

  17. Carbohydrates • Dietary sources • Starch (complex carbohydrates) in grains and vegetables • Sugars in fruits, sugarcane, sugar beets, honey and milk • Insoluble fiber: cellulose in vegetables; provides roughage • Soluble fiber: pectin in apples and citrus fruits; reduces blood cholesterol levels

  18. Carbohydrates • Dietary requirements • Minimum 100 g/day to maintain adequate blood glucose levels • Recommended minimum 130 g/day • Recommended intake: 45–65% of total calorie intake; mostly complex carbohydrates

  19. Carbohydrates • Dietary Fiber • water-insoluble fiber adds bulk to fecal matter facilitating its passage through and elimination from the digestive system • water-soluble fiber may absorb dietary cholesterol, reducing its absorption by the digestion tract

  20. Wheat Seed

  21. Lipids • C H O (P) • 9 kcal/gram • Body’s alternate source of energy • Use fat along with glucose as an energy source most of the time • Stores are unlimited

  22. Lipids • Dietary sources • Triglycerides • Saturated fats in meat, dairy foods, and tropical oils • Unsaturated fats in seeds, nuts, olive oil, and most vegetable oils • Cholesterol in egg yolk, meats, organ meats, shellfish, and milk products

  23. Lipids • Essential fatty acids • Linoleic and linolenic acid, found in most vegetable oils • Must be ingested

  24. Lipids • Essential uses of lipids in the body • Help absorb fat-soluble vitamins • Major fuel of hepatocytes and skeletal muscle • Phospholipids are essential in myelin sheaths and all cell membranes

  25. Lipids • Functions of fatty deposits (adipose tissue) • Protective cushions around body organs • Insulating layer beneath the skin • Concentrated source of energy

  26. Lipids • Regulatory functions of prostaglandins • Smooth muscle contraction • Control of blood pressure • Inflammation • Functions of cholesterol • Stabilizes membranes • Precursor of bile salts and steroid hormones

  27. Lipids • Dietary requirements suggested by the American Heart Association • Fats should represent 30% or less of total caloric intake • Saturated fats should be limited to 10% or less of total fat intake • Daily cholesterol intake should be no more than 300 mg

  28. Pathways of Lipid Metabolism

  29. Atherosclerosis diseased normal

  30. Your Cholesterol Level • Cholesterol: <175 mg/dl • Triglycerides: blood fats, 30-175 mg/dl • HDL: Good cholesterol, > 35 mg/dl • LDL: Bad Cholesterol, <130 mg/dl • Chol/HDL ratio: < 4.5 indicates heart disease

  31. Protein • C H O N • 4 kcal/gram • Body’s least desirable source of energy • WHY? • Protein is used for energy only when there isn’t any carbohydrate available as an energy source.

  32. Proteins • Enzymes • Structural proteins (shape and form of cells and tissues) • Hormones • Immunoglobulins (antibodies)

  33. Essential Amino Acids • Tryptophan • Methionine • Valine • Threonine • Phenylalanine • Leucine • Isoleucine • Lysine • Arginine • Histidine • (infants)

  34. Proteins • Dietary sources • Eggs, milk, fish, and most meats contain complete proteins • Legumes, nuts, and cereals contain incomplete proteins (lack some essential amino acids) • Legumes and cereals together contain all essential amino acids

  35. Proteins • Uses • Structural materials: keratin, collagen, elastin, muscle proteins • Most functional molecules: enzymes, some hormones

  36. Proteins • Use of amino acids in the body • All-or-none rule • All amino acids needed must be present for protein synthesis to occur • Adequacy of caloric intake • Protein will be used as fuel if there is insufficient carbohydrate or fat available

  37. Proteins • Nitrogen balance • State where the rate of protein synthesis equals the rate of breakdown and loss • Positive if synthesis exceeds breakdown (normal in children and tissue repair) • Negative if breakdown exceeds synthesis (e.g., stress, burns, infection, or injury)

  38. Proteins • Hormonal controls • Anabolic hormones (GH, sex hormones) accelerate protein synthesis

  39. Vegetarian diet may result in protein deficiency • Need essential amino acids • beans  lysine & isoleucine • corn  tryptophan & methionine

  40. Transamination

  41. Energy-Yielding Non-nutrient • Alcohol – 7 kcal/gram • Non-nutrient because it interferes with growth, maintenance and repair of the body • Alcohol’s metabolites are harmful

  42. Energy Density • Measure of the kcal per gram of food • Fat has the highest energy density of the 3 energy-yielding nutrients. • Foods with a high energy density provide more kcal per gram than low density foods.

  43. Energy Density

  44. Vitamins • Essential • Organic, micronutrient • Not energy-yielding • Fairly easily destroyed/damaged • Can be water-soluble or fat-soluble

  45. Vitamins Organic compounds needed by the body in small, but essential amounts Cannot be synthesized by the body in sufficient amounts Function in a variety of ways in metabolic reactions Thirteen known vitamins

  46. Water-Soluble Vitamins C (ascorbic acid) B1 (thiamin) B2 (riboflavin) Niacin B6 (pyridoxine) Pantothenic acid Biotin B12 (cyanocobalamin) Folic acid

  47. Water-Insoluble Vitamins A (retinol) D E K

  48. Minerals • Essential • Inorganic, micronutrient • Not energy-yielding • Indestructible

  49. Minerals • Essential inorganic elements • Involved in a variety of metabolic processes • Major minerals versus trace minerals

  50. Major Minerals Calcium Phosphorus Magnesium Sodium Potassium Chlorine

More Related