Introduction to Nutrition Summer I, 2008

1. Introduction to NutritionSummer I, 2008 Lecture 1, Chapter 1

2. What You Eat and Why • Are carbs a major source of health problems? • Is a high protein / high fat diet effective? • Which foods are unsafe and why? • What about supplements? • Should I become a vegetarian? • If I am predisposed to a disease how can my diet aid in prevention?

3. What do we know • DIET AND EXERCISE – the only 2 proven ways to your optimum physical health • Whole grains and fiber • Fresh and/or frozen fruits and vegetables • Low fat dairy products and lean protein • Oils containing omega-3 FA’s • But how does each contribute to overall health and in what amounts?

4. What is Nutrition? • Nutrition – the science that links foods to health and disease • Includes all bodily functions that result in the breakdown, storage, metabolism and excretion of foods. • Nutrients – Substances obtained from food that are vital for growth and maintenance of a healthy body throughout life

5. What is Nutrition? • Essential nutrient consists of 3 characteristics: • Must have at lease 1 specific biological function • Omission of the nutrient must lead to a decline in certain biological functions • Replacing the nutrient before permanent damage occurs will restore the function

6. Why Should We Study Nutrition? • Its required for graduation • Understanding nutrition and its effects helps prevent multiple health issues • Heart disease • Obesity • Hypertension • Diabetes • Cancer • Macular Degeneration • Scurvy Courtesy NIHNational Eye Institute

7. Effects of Nutrition on Health • Dietary neglect in younger years may contribute to health problems later • Calcium deficiency and osteoporosis • However, too many nutrients, such as vitamin supplements, could also have a harmful effect • Selenium abundance and prostate cancer

8. Diet and Exercise • Poor diet combined with lack of exercise contributes to 350,000 deaths per year • Obesity is considered the second leading cause of “preventable” death in the US behind smoking. • Smoking and obesity together

9. What influences daily food choices? • Taste • Appearance • Convenience • Nutrition http://cosmos.bcst.yahoo.com/up/player/popup/index.php?cl=7383765

10. Classes and Sources of Nutrients • 6 major types of nutrients with many sources • Carbohydrates • Lipids • Proteins • Vitamins • Minerals • Water

11. Classes and Sources of Nutrients • Functions of nutrients fit into 3 major categories (with some overlaps) • Provide calories to sustain energy needs • Support growth, development and maintenance • Keep the body’s function running smoothly

12. Carbohydrates • Composed of mainly carbon, hydrogen and oxygen • Provide major source of calories • Simple sugars or complex carbs • Monosaccharides and disaccharides • Polysaccharides and starch • Brain cannot function without glucose

13. Carbohydrates • During digestion, sugars are broken down into single sugars and transported to the blood stream • Some bonds between sugars cannot be broken (fiber) • Fiber passes through the digestive system adding bulk to wastes for intestinal health Humans lack the symbiotic bacteria found in the guts of termites to breakdown cellulose.

14. Lipids • Fats and oils that consist of mostly carbon and hydrogen with minimal oxygen • Fats are solid at room temp • Oils are liquid at room temp • Hydrophobic – do not dissolve in water http://www.flickr.com/photos/boclcown/350894519/

15. Triglycerides Saturated fats, solid at room temperature, should be avoided as they can increase cholesterol levels in the bloodstream leading to cardiovascular disease. “Bad Fats” Kinks in the FA chains of unsaturated lipids prevent close packing and therefore are liquids at room temperature. “Good Fats” http://instruct.westvalley.edu/svensson/Cells/07molecules.htm

16. Trans Fats • Trans fatty acids are typically found in processed foods, especially those deep fried in oils containing trans fats • New movement to remove trans fats from fast food restaurants and provide content on nutrition labels • Why are they worse then regular fatty acids?

17. Trans Fats • Industrially created by partially hydrogenating plant oils — ex. Crisco • Hydrogenation adds hydrogen atoms to unsaturated fats, making them more saturated • Increases shelf-life and stability • Neither essential nor health promoting • Consumption increases risk of coronary heart disease by raising levels of "bad" LDL cholesterol and lowering levels of "good" HDL cholesterol

18. Omega – Fatty Acids • Unsaturated fatty acids which are essential nutrients only obtained from food • Health benefits include the following: • Reduce varicose veins • Stimulates blood circulation • Improves blood clotting ability • Reduce triglyceride levels • Prevent heart attacks Photo: Greg Totman

19. Proteins • Composed of carbon, hydrogen and oxygen, but also nitrogen • Main structural material of the body • Muscle, Hair, Nails, Skin • But also in its function • Enzymes, blood components, immune factors • Proteins are formed when amino acids join together

20. Proteins • Amino Acid – building block for proteins containing a central carbon atom with nitrogen and other atoms attached • 20 common amino acids are found in food, 9 are essential for adults – Se is 21staa • Most NA’s eat ~2X more protein daily than the body needs • Leads to fat storage and carbohydrate production

21. Proteins http://www.genome.gov//Pages/Hyperion//DIR/VIP/Glossary/Illustration/amino_acid.cfm

22. Vitamins • Variety of chemical structures and include C, H, N, O, P, S and others • Main purpose is to enable many chemical reactions to occur in the body • Provide no usable calories for energy • 13 vitamins are divided into 2 groups: fat-soluble and water-soluble

23. Fat-Soluble Vitamins • Vitamins A, D, E and K • Dissolve in fat • Must be consumed with fat and are then stored in fat tissue • Not easily destroyed by cooking • More likely to accumulate in toxic amounts http://www.flickr.com/photos/almaz/19540477/

24. Water-Soluble Vitamins • Vitamin C and the B Vitamins • Dissolve in water • Cooking destroys these vitamins • Excreted from the body readily • Expensive pee http://www.whfoods.com/genpage.php?tname=nutrient&dbid=100

25. Minerals • Simple, inorganic substances which do not contain carbon • Not destroyed during cooking, but can be discarded in cooking water • Critical players in nervous system, cellular processes, water balance and structure (skeleton) • Provide no calories for energy

26. Minerals • ~ 16 essential minerals are required for good health • Amounts of each vary enormously • Divided into 2 groups: major minerals and minor minerals • Minor (trace) = < 100 mg needed per day, Zn ( 15 mg / day) • Major = > 100 mg needed per day, Ca (1 g / day)

27. Water • Often overlooked as a nutrient, water has many vital functions • Solvent and lubricant, transports wastes, temperature regulation • Body is ~ 60% water • Men need ~ 13 cups / day and women ~ 9 cups / day http://www.fastcompany.com/magazine/117/features-message-in-a-bottle.html

28. Phytochemicals • Phytochemicals – found in plants that may contribute to a reduced risk of cancer or cardiovascular disease when consumed regularly • Not considered essential • Available only in whole foods, can’t be bottled • Usually content is directly related to color intensity http://nihseniorhealth.gov/takingmedicines/sideeffects/citrus_popup.html

29. Nutrient Composition • Amount of nutrients consumed each day vary widely • Amount of nutrients in each food can also vary per item • Genetics plays a large part in how these nutrients are processed by cells • Cells don’t care if protein comes from animal or plant • Food provides cells with the basic materials to function

30. Nutrient Composition

31. Energy Sources and Uses • Calories needed for energy obtained from carbs, lipids and protein • Food generally provides more than 1 source of calories • Exception is plant oils, 100% fat • Alcohol is also a source of calories (7 kcal / g) • Not considered essential • Beer is rich source of carbohydrate

32. Energy Sources and Uses • Energy is obtained by breaking chemical bonds within these nutrients • ATP  ADP generates body heat • Converted into other types of energy: • Build new compounds • Perform muscular movement • Promote nerve transmission • Maintain ion balance within cells

33. Energy Sources and Uses • Quick note about calories: • calorie (lower case) – the amount of heat energy required to raise the temperature of 1 gram of water 1 oC • A calorie is a very small amount, so we measure food energy in kilocalories (kcal) • On US food labels, Calorie (uppercase) is actually a kcal • European food labels list as kcal and/or kJ

34. Energy Sources and Uses • Carbohydrates = 4 kcal / gram • Lipids = 9 kcal / gram • Protein = 4 kcal / gram • Alcohol = 7 kcal / gram The 4-9-4 estimate

35. Metric System • The metric system is always used as the method of measure in science and medicine fields • Babies are now being weighed in kg to prevent dosage errors with medications measured in mg 1 kg = 1000 g = 2.2 lbs

36. Calculating Calories in Food • Use the 4-9-4 estimate to calculate the calorie content of carbohydrate, fat and protein in a typical ham and cheese wrap: Carbs 10g Fat 12g Protein 35g TOTAL

37. Calculating Calories in Food • Use the 4-9-4 estimate to calculate the calorie content of carbohydrate, fat and protein in a typical ham and cheese wrap: Carbs 10g x 4 = 40 kcal Fat 12g x 9 = 108 kcal Protein 35g x 4 = 140 kcal TOTAL = 288 kcal

38. North American Diet • List negative attributes of the North American Diet • List positive attributes • How does our lifestyle impact our choices? USDA - 1992 USDA - 2005

39. North American Diet

40. Improving Our Diets • Much advertising is done to inform the public • fiber, whole wheat, oatmeal, calcium, trans fats, anti-smoking ads, physical activity • However we are still eating more cereal, pizza, pasta, fried and processed foods than before • The importance of a varied diet is paramount coupled with daily activity

41. Why Am I So Hungry? • We eat for 2 general reasons: hunger and appetite • Hunger – biological drive to eat, controlled by the internal body mechanism • Signals are sent to the brain and liver to reduce further food intake • Appetite – psychological drive to eat, stimulated by our senses

42. Why Am I So Hungry? • Satiety – state in which there is no longer a desire to eat, a feeling of satisfaction • The hypothalamus (region of the brain) helps regulate satiety – dysfunction can be extreme • There is a delicate balance between feeding and satiety in the hypothalamus – takes time for us to realize the difference • Of course the cortex (conscious thought) can overcome satiety and we binge on “good food”

43. Why Am I So Hungry? • What physical events reduce our desire to eat more? • Stomach expansion • Nutrient absorption in intestines • Researchers have shown that bulky meals (high in fiber and water) produce much more satiety • Volumetrics diet (Penn State University)

44. Why Am I So Hungry? • Hormones also influence food choices • Endorphins, gherlin and neuropeptide Y all increase hunger • Serotonin, leptin and cholecystokinin (CCK) cause satiety

45. Why Am I So Hungry? • Leptin, made by fat cells, travels to the brain to turn off the hunger center • Gherlin, made in the stomach travels to the brain to turn on the hunger center and decrease satiety • High leptin levels can turn off gherlin production • An imbalance of either can cause insensitivity to leptin or hypersensitivity to gherlin

46. Controlling Hunger • Eat breakfast • Eat smaller, more frequent meals • Avoid sugary foods, including carbs • Focus on a protein / fat snack (hardboiled egg) • Balance your nutrients daily • Know your triggers and avoid them • Listen to your body!

47. Why Am I So Hungry? • What /who influenced you today? • If negative, how can you avoid these triggers?

48. Eating Well in College