Introduction to Human Nutrition

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? • Food contain 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. Nonessentail Nutrients • 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. 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

13. Energy-Yielding Nutrients

14. 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)

15. 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

16. 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

17. 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

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

19. 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

20. 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.

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

22. 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

23. 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

24. 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.

25. Energy Density

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

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

28. Improving your Health • Goal is to reduce the number of risk factors that are in your control • Risk factor = something that statistically increases the incidence of a disease • Risk factors may not be the cause of the disease………

29. Nutritional Deficiencies • Overt vs. covert deficiency • Overt – outward signs of the deficiency • Covert or sub-clinical– deficiency may be detected by lab tests, but not outward signs of the deficiency

30. Nutritional Deficiencies Primary vs. secondary deficiency • Primary – inadequate intake of the nutrient • Secondary – body doesn’t absorb adequate amounts, excretes too much…. • Body “mishandles” the nutrient

31. Obesity • Here are the top 5 obese countries: • United States • 34% of adults were overweight in 2008 • 66% are overweight in 2012 • Mexico • New Zealand • Australia • United Kingdom Lowest: Japan & Korea 3.2%

32. Obesity

33. Artificial Sweeteners • Reduced calories • Reduce tooth decay • Diabetes • Lower cost

34. Artificial Sweeteners • Acesulfame potassium (Sunett, Sweet One) • Aspartame (Equal, NutraSweet) • Neotame • Saccharin (SugarTwin, Sweet'N Low) • Sucralose (Splenda) http://www.youtube.com/watch?v=A-hUyw2lcio

35. Find one source saying that artificial sweeteners are safe and one saying that they are dangerous. Which source is more credible? • Why? • Is it backed by SCIENTIFIC research • Is it from a credible entity?