Chapter 25: Nutrition Food and Diet

Transcription

1 Chapter 25: Nutrition Food and Diet Lecture Outline Enger, E. D., Ross, F. C., & Bailey, D. B. (2012). Concepts in biology (14th ed.). New York: McGraw- Hill. 25-1

2 Living Things as Chemical Factories: Matter and Energy Manipulators 25-2 All organisms need energy and building blocks to live and grow. Nutrients All of the molecules required to support life Includes inorganic elements and organic molecules Nutrition The branch of science that studies food Also refers to the process by which we take in food and utilize it Diet All of the food and drink consumed by an organism

3 The Process of Nutrition 25-3 Ingestion Taking food into the body through eating Digestion The breakdown of complex food molecules to smaller molecules Absorption The movement of smaller molecules from the digestive system to the circulatory system Assimilation The modification and incorporation of absorbed molecules into the structure of the organism

4 Kinds of Nutrients and their Function Nutrients are divided into six major categories: Carbohydrates Lipids Vitamins Minerals Water 25-4

5 Carbohydrates 25-5 Sugars Mono- and disaccharides Glucose, sucrose Most taste sweet Used in cellular respiration Provides the energy to make ATP Complex carbohydrates Polysaccharides Starch, glycogen Broken down into monosaccharides Cellulose Indigestible Slows absorption and stimulates peristalsis (dietary fiber)

6 Too Little/Too Much Carbohydrate Low carbohydrate diets Result in fats and proteins being metabolized for energy Generates keto acids which can alter body ph Can generate high levels of toxic nitrogen waste High carbohydrate diets The energy from excess carbohydrates is stored as fat. Usually result in weight gain 25-6

7 Lipids 25-7 Includes triglycerides, phospholipids and steroids Phospholipids make up cell membranes. Cholesterol is a steroid. Triglycerides are the true fats. Excellent source of energy Release 2.5 times as much energy as carbohydrates Essential fatty acids must be acquired by diet. Humans cannot make them. Vitamins A, D, E and K are lipids and will not be absorbed unless fat is present. Insulate organs Serve as a shock absorber

8 Proteins 25-8 Composed of amino acids Complete proteins Contain all of the amino acids necessary for good health Incomplete proteins Lack certain amino acids needed by the body Essential amino acids Cannot be made by the human body Must be obtained from the diet Can be used for energy if the body runs out of carbohydrate

9 Protein-sparing 25-9 Proteins cannot be stored and used later. Only small amounts of protein are lost each day that need to be replaced. Therefore, we only need a small amount of protein in our diet. Our bodies oxidize sugar and fats for energy before proteins. During starvation, amino acids must be converted to sugars. RBCs and nerve cells need glucose for energy. Cannot use fats This is what makes starvation fatal.

10 Vitamins Organic molecules needed in small amounts to help enzymes work properly. Do not provide energy Serve as coenzymes Cannot be made by humans Most are acquired from food Vitamin D is made in our bodies when UV light hits cholesterol

11 Too Much of a Good Thing High levels of some vitamins can be toxic Fat soluble vitamins (A, D, E, K) cannot be excreted. Are stored in fat Excess vitamin A can cause joint pain, loss of hair, jaundice, etc. Excess vitamin D causes calcium deposits in the kidneys and blood and bone pain

12 Minerals Inorganic elements Cannot be synthesized by the body Functions Enzyme regulators and cofactors Magnesium Involved in neurotransmission Sodium, potassium Oxygen transport Iron Anemia-iron deficiency Bone structure Calcium Osteoporosis-calcium deficiency

13 Water Essential to life The human body is 65% water. Is able to dissolve most solutes Universal solvent Solutions of ions are called electrolytes because when in solution they can conduct electricity. Many wastes are soluble in water, allowing for easy elimination. Urine produced by kidney Evaporation from skin or lungs Most chemical reactions in organisms occur in water. The breakdown of food requires water Hydrolysis

14 Dietary Reference Intakes Guidelines for maintaining good health Very specific for men, women, children, pregnant women, etc. Published by the USDA Used in preparing food labels Labels list ingredients from greatest to least in quantity Also provide caloric information and amounts of various nutrients 25-14

15 Dietary Reference Intakes for Several Nutrients 25-15

16 The Food Guide Pyramid A simple guide to planning diet Generated by the department of agriculture 25-16

17 Grain Includes vitamin-enriched or whole-grain cereal Breads, bagels, cereals, crackers, pasta, etc. Recommended amounts Women - 6 oz. Men - 8 oz. 1 slice of bread = 1 oz. Whole grains are the best. Provide fiber that facilitates digestion Satisfy appetite Low in fat 25-17

18 Fruits A botanical term for an enlarged or modified ovary of a plant Nutritionally, a fruit is classified as any plant product that is sweet and not eaten during the main meal. Melons, berries, apples, oranges and bananas 1-2 cups per day are recommended. The sugar can add calories to one s diet

19 Vegetables Nutritionally defined as plant material that is not sweet and is eaten with the main meal. 4.5 cups a day are recommended. Include Broccoli, carrots, cabbage, corn, green beans, lettuce, tomatoes, potatoes, etc. Positive health benefits Cancer protection Vitamins Provide fiber

20 Milk Includes Cheese, ice cream, yogurt, and milk 2-3 cups a day are recommended. 1.5 oz. of cheese is one serving. Many are fortified with vitamin D. Many have high levels of cholesterol and fat.

21 Meat and Beans Usually our main source of protein Includes Beef, chicken, fish, nuts, beans, peas, tofu, eggs oz. per day are recommended. Daily intake is needed since protein cannot be stored. Animal proteins are complete proteins. Usually contain high levels of fat Plant proteins are incomplete proteins. Usually do not have high levels of fat Different plants must be combined to obtain all essential amino acids.

22 Oils Needed to obtain essential fatty acids Have high caloric content Must be eaten in moderation Should comprise less than 10% of total calories eaten in a day. Unsaturated is better than saturated Fish, nuts, vegetable oils are unsaturated. Solid fats come from animals and are mostly saturated. Trans fats boost levels of LDL, triglycerides and cholesterol, and decrease HDL levels.

23 Exercise Affects the number of food calories that can be consumed without gaining weight 30 minutes a day is recommended. Must elevate heart rate Has a number of additional advantages 25-23

24 Common Activities 25-24

25 Diet and Weight Control Kilocalorie The unit used to measure the amount of energy in food. The amount of energy needed to raise the temperature of one kilogram of water 1 degree Celcius. Also called a Calorie (with a capital C) or a food calorie A calorie is 1/1000 of a kilocalorie. Lowercase c

26 Basal Metabolic Rate At rest, energy is used to maintain Breathing Heart rate Digestion Body temperature The rate at which the body uses energy at rest Is called the basal metabolic rate Can be measured by quantifying the oxygen used over a specific period

27 Basal Metabolic Rate Age, gender, height, and weight all affect basal metabolic rate. Children higher than adults Males higher than females Larger people higher than smaller people When we are not at rest, we need more energy. For digestion Specific dynamic action is the amount of energy needed to process food. For activity Will depend on one s daily activity

28 Additional Kilocalories Needed by Occupation 25-28

29 Body Mass Index (BMI) The USDA has published guidelines that will help people evaluate their weight. Educates people about the dangers of obesity Body mass index Evaluates weight based on height Calculated by dividing weight in kilograms divided by height in meters squared Obesity A BMI of over 30kg/m 2 is considered obese. Drawback: BMI doesn t measure fitness A measure of how efficiently a person can function physically and mentally

30 Body Mass Index 25-30

31 Weight Control We gain weight because our body can store carbohydrates and fat. Allows the body to access energy stores during times that food is scarce. However, since food is rarely scarce today, the excess that we eat is stored as fat and never used. Weight control Balancing kilocalories ingested with kilocalories expended Decreasing caloric intake by calories per day will result in a 1-2 lb. weight loss per week. Likewise, adding calories per day will result in a 1-2 lb. weight gain per week.

32 Controlling Your Weight Eating and Exercise So, how does one lose weight? Determine how many kcal/day you are eating. Can be done by writing down everything you eat Use food labels and nutrition books to estimate calories per food item. Determine how many kcal/day you are burning. Write down all activity. Estimate kcal burned per activity. To lose weight Decrease kcal/day eaten by 500 kcal/day. Increase kcal/day of activity.

33 Obesity The condition of being overweight to the point where a person s health and lifespan are adversely threatened. Occurs when people eat more calories than they use Individuals who have a BMI of 30 or more are obese. Incidence is increasing because our activity level is decreasing. Sedentary death syndrome Due to cultural and social factors Genetic studies also indicate there may be a genetic component to obesity. May involve a chemical imbalance in the brain

34 Bulimia A disease involving a cycle of eating binges followed by purging the body of food. Purging may involve vomiting or the use of laxatives or diuretics. Caused by psychological factors Can involve depression The binge-purge cycle has several negative health effects. Dehydration, diminished blood volume, mineral deficiencies, kidney malfunction, lethargy, etc.

35 Anorexia Nervosa A nutritional deficiency disease characterized by severe, prolonged weight loss Involves voluntary, severe restriction of caloric intake Caused by an extreme fear of becoming overweight Anorexics have a distorted perception of their body. Severe caloric deficiency (starvation) results in Hair loss, constipation, amenorrhea, decreased heart rate, osteoporosis, etc

36 Muscle Dysmorphia Obsession with being muscular Under-diagnosed in men Compulsion to bulk up may lead to overexercising and anabolic steroid use 25-36

37 Deficiency Diseases Protein-deficient diets can lead to deficiencies in essential amino acids. In some countries, many people live mainly on carbohydrates and fats. Without all of the essential amino acids, enzymes cannot be made properly. Kwashiokor is one type of protein deficiency. Results in a distended belly, slow growth, slow movement and depression 25-37

38 Deficiency Diseases Starvation Due to too little carbohydrates The body will begin using fat stores and protein for energy. The breakdown of amino acids and fatty acids generates keto acids. When fat stores are gone, proteins are used exclusively for energy. Usually leads to death 25-38

39 Starvation and Stored Foods 25-39

40 Nutrition During Infancy A person s total energy needs per kg are greatest during the first year of life. 50% of an infant s caloric intake is used to maintain its basal metabolic rate. Infants triple their weight and increase 50% in height over the first year of life. Therefore, they need nutritionally rich food with high caloric value

41 Human Breast Milk vs. Cow s Milk 25-41

42 Childhood Rate of growth slows after the first year The body becomes more lean, bones elongate and the brain completes its growth. Protein intake needs to accommodate growth of new tissues. Minerals need to be present to support growth

43 Adolescence During this stage, the body changes from non-reproductive to reproductive. Puberty lasts 5-7 years. Individuals gain up to 20% of their adult height and 50% of their adult weight. Female body fat increases from 15%-23%. Males experience a second growth spurt

44 Adulthood A plateau phase Nutrition should be focused on maintenance. Caloric intake should simply replace calories used. As age increases, BMR decreases. This means that caloric intake should decrease as age increases

45 Old Age Digestion and absorption slows as age increases. Mitosis decreases, reducing the overall number of cells. Organs begin to function less well. BMR decreases, physical activity decreases, eating decreases. Nutritional deficiencies result. Linoleic acid levels become low; vegetable oil supplements may be necessary. Vitamin and mineral supplements may be necessary. Calcium and iron Exercise is very important to prevent muscle loss

46 Nutritional Needs Associated with Pregnancy and Lactation Special nutrient requirements for fetal growth and milk production BMR is increased. Therefore, daily requirements are increased. Nutrients Protein intake increased to 65 g/day Folic acid and iron supplements should be taken. Calories increased 300 kcal/day Heavy smoking and excessive alcohol use can interfere with nutrient exchange between baby and mother. Fetal alcohol syndrome

47 Nutrition for Fitness and Sports Cellular respiration mobilizes the energy needed for exercise. Uses glucose, fatty acids, or amino acids Glucose from stored glycogen is used first. Fatty acids from stored triglycerides is used next. Amino acids are rarely utilized during exercise. Makes the ATP needed for muscle contraction 25-47

48 Aerobic Exercise When the level of exertion allows the heart and lungs to keep up with the oxygen demand of the muscles Cellular respiration can provide the ATP needed. During the first 20 minutes, glucose and glycogen is used. After 20 minutes, triglycerides and fatty acids are used. When glycogen stores are depleted, athletes hit the wall

49 Anaerobic Exercise Bouts of exercise that are so intense that the muscles cannot get oxygen as fast as they need it. Glycolysis provides the ATP (since oxygen is not present). Fermentation must be used to keep glycolysis going. Only glucose and glycogen can be used

50 Diet and Training Endurance athletes can prevent hitting the wall by carbohydrate loading. A week-long process of exercising and eating high carbohydrate foods Conditioning involves Training to increase strength of muscles Practicing movements for smooth execution Increasing the efficiency of the heart, lungs, skeletal muscles, and cells

51 Diet and Training Protein supplementation Eating additional proteins will not result in an increase in muscle mass unless one is exercising and placing demands on the muscles. Water intake Water loss can decrease muscular activity. Drinking water before and during exercise is necessary to prevent dehydration