Chapter 1- An Overview of Nutrition PDF

Preview

Summary

Download Chapter 1- An Overview of Nutrition PDF

Description

CHAPTER 1: AN OVERVIEW OF NUTRITION (Pg. 1- 37) - What is nutrition and Why is it important to study? - Have you ever thought of the various factors that influence your food choices? - How can you tell reliable from misleading nutrition information? Chronic Diseases = time Progresses slowly Little changes Lasts a long time

Acute Diseases = sharp Progresses quickly Sharp symptoms Runs a short time

1.1Food Choices: Describe how various factors influence personal food choices Definitions: Nutrition: the science of foods and the nutrients they contain, and of their actions within the body (including ingestion, digestion, absorption, transport, metabolism, excretion). In general, the social, economic, cultural and psychological implications of food and eating. Foods: products derived from plants and animals that can be taken into the body to yield energy and nutrients for the maintenance of life and the growth and repair of tissues Diet: the foods and beverages a person eats and drinks Ethnic food: foods associated with specific cultural groups Cultural competence: having an awareness and acceptance of cultures and the ability to interact effectively with people of diverse cultures Functional Foods: foods that contain physiologically active compounds that provide health benefits beyond their nutrient contributions; sometimes called designer foods Phytochemicals: non- nutrient compounds found in plant-derived foods that have biological activity in the body.

1) Personal Preferences  Number one reason people choose food is taste – they like certain flavors  Two widely shared preferences: sweetness of sugar and savories of salt  Liking high-fat foods seems to be universally common preference  Research shows genetics may influences taste perceptions – food likes and dislikes  Hormones of pregnancy seem to influence food cravings and aversions 2) Habit  Select foods that they just regularly eat; familiar food – don’t need to make decisions can be comforting 3) Ethnic Heritage and Tradition  People tend to prefer food they grow up eating  Every country, and every region of a country has its own typical foods and ways of combining them into meals  People offering ethnic foods are sharing a part of their culture and those accepting it learn about another way of life 4) Social Interactions  People enjoy companionship while eating and tend to eat more food when they go out with others  Accepting food or drink offered by people and sharing food/drink with others 5) Availability, Convenience, and Economy  People eat foods that are quick and easy to prepare within their financial means  Consumers emphasis on convenience limits food choices to those that can be prepared quickly  Due to the rise in food costs, its shifted consumer’s priorities and now more people make more home cooked meals at home rather than eating out

6) Positive and Negative Associations  People tend to like foods associated with happy occasions – ice cream cake = birthday party and can develop taste aversions to foods they ate when they were sick or forced to eat as a child.  By using foods as rewards and punishments parents teach their children inadvertently to like and dislike certain food 7) Emotions  Some people can’t eat when emotionally upset, but others may eat in response to emotional stimuli such as boredom 8) Values  Food choices can reflect person’s religious beliefs, political views or environmental concerns 9) Body Weight and Image  Sometimes people select certain food and supplements that they think will improve their physical appearance and avoid those they believe may be detrimental  These decisions can be beneficial if the right knowledge is used when making decisions but if based on fads or taken to extremes good lead to poor health 10) Nutrition and Health Benefits  Many consumers make food choices that will benefit their health  Food that’s provide health benefits beyond their nutrient contributions are called functional foods  Consumers normally welcome new foods to diet if: reasonably priced, clearly labelled, easy to find in grocery store and convenient to prepare 1.2The Nutrients: Name the 6 classes of nutrients and identify which ones are organic and which yield energy 1)Carbohydrates 2)Lipids (fats) 3)Proteins 4)Vitamins 5)Minerals 6)Water

Definitions: Energy: the capacity to do work. Energy in food is chemical energy. The body can convert this chemical energy to mechanical, electrical or heat energy. Nutrients: chemical substances obtained from food and used in the body to provide energy, structural materials, and regulating agents to support growth, maintenance and repair of body’s tissues. Nutrients may also reduce risk of some diseases. Inorganic: not containing carbon or pertaining to living things Organic: in chemistry, a substance or molecule that contains carbon-carbon bonds or carbon hydrogen bonds Essential nutrients: nutrients a person must get from food because body cannot make sufficient amounts of it to meet physiological needs Energy density: measure of energy a food provides relative to the amount of food Nutrient Density: measure of nutrients a food provides relative to the energy it provides  Skin is replaced entirely by new cells every 7 years  Oldest red blood cell is only 120 days old  Entire lining of your digestive system is renewed every 2-7 days Nutrients in Food and in the Body: Nutrients foods deliver and how they participate in dynamical processes that keep us alive and well Nutrient Composition of Foods  Most of the solid materials are carbohydrates, lipids and proteins. If you could remove these materials you would find tiny residue of vitamins, minerals and other compounds  The Six Classes of Nutrients are substances body uses for growth, maintenance and repair of its tissues Nutrient Composition of the Body  Our body is made up of similar materials found in foods  A healthy 70 kg (150 lb) body contains: 42 kilograms (90 lb) of water and about 10 to 20 kg (20 to 45 lbs) of fat. The remaining kilograms are mostly protein, carbohydrates, and the major minerals of the bones. Vitamins, other minerals, and incidental extras constitute a fraction of a kilogram – refer to Pg. 6 Figure 1-1 Chemical Composition of Nutrients

 Simplest of nutrients is a mineral. Each mineral is a chemical element; its atoms are alike therefore its identity never changes Ex: Iron may have different electrical charges, but the individual iron atom remains the same when a person eats food and iron becomes part of a red blood cell – can be broken down and lost by excretion  The next simplest nutrient is water, compound made of two elements— hydrogen and oxygen. Minerals and water are chemically inorganic which means they do not contain carbons.  The other four classes of nutrients (carbohydrates, lipids, proteins, and vitamins) are more complex. In addition to hydrogen and oxygen, they all contain carbon, an atom found in all living things, therefore called chemically organic nutrients. Table 1-1: Elements in the Six Classes of Nutrients Carbon Hydrogen Oxygen Nitrogen Minerals Inorganic Nutrients Minerals ----------Water --------------------Organic Nutrients Carbohydrate ------------------------Lipid (fat) ---------------------------Protein -------------------------------------Vitamins ----------------------------*Some proteins also contain the mineral Sulphur *Some vitamins contain nitrogen; some contain minerals Essential Nutrients  the nutrients food must supply are essential nutrients The Energy Yielding Nutrients: Carbohydrate, Fat and Protein  Carbs, fats and proteins sometimes called macronutrients because they are required by the body in large quantities. In contrast, vitamins and minerals are called micronutrients because they’re required in small quantities.  International unit for measuring food energy is a joule K cals  KJ ……X 4.2 KJ  K cals X… 0.24 Energy Measured in kCalories

 Energy released from these energy yielding nutrients can be measured in calories Energy from Foods  Amount of energy provided by food depends on how much of these 3 energy-yielding nutrients it contains  When completely broken down a gram of protein and carbs yields about 4 kCalories and a gram of fat yields 9 kCals. Alcohol has 7 kCals  Foods with high energy density deliver more kcalories than foods with low energy density **Conversions on Page 8/9 if needed** Energy in the Body  When the body uses energy-yielding nutrients, the bonds between the nutrients atoms break. As the bonds break they release energy. Some of this energy is released as heat energy, but some of it is used to send electrical impulses through the brains and nerves, to synthesize body compounds and move muscles.  If body is not using these nutrients to fuel its current activities, converts them into storage compounds (such as body fat) to be used when energy supplies run low.  If more energy is consumed than expended, the result is an increase in energy stores and weight gain, vice versa. Other Roles of Energy Yielding Nutrients  Provide raw materials for building the bodies tissues and regulating many activities  Protein are found in structures such as muscles and skin to help regulate activities such as digestion and energy metabolism The Non-Energy Yielding Nutrients: Vitamins, Minerals and Water  Do not directly yield energy, but support the production of energy from the three energy-yielding nutrients The Vitamins  Vitamins are organic but do not provide energy. They facilitate the release of energy from carbs, proteins and fats and participate in numerous other activities in the body  Each of the 13 vitamins plays its own special role. Ex. One helps you see in dim light, another helps protect lungs from air pollution, and still another help make sex hormones, one helps stop bleeding when you cut yourself, one repairs the skin.

 Vitamins help replace old red blood cells and the lining of the digestive tract  Vulnerable to destruction by heat, light and chemical agents and can only function if they are intact The Minerals  Put together in orderly arrays in such structures as bones and teeth and can also be found in the fluids of the body, which influences fluid balance and distribution.  Only 16 minerals known to be essential in human nutrition. Some are studied to see if they play a significant role. While others are environmental contaminants such as lead, and can displace nutrient minerals, disrupting body functions  They are inorganic so therefore are indestructible and don’t need to be handled with special care  Can be bound by substances that interfere with the body’s ability to absorb them, and can also be lost during food refining processes or during cooking when they leach into water that is discarded Water  Provides the environment for in which nearly all the bodies activities are conducted  Participates in many metabolic reactions and supplies the medium for transporting vital materials to cells and carrying waste products away from them 1.3The Science of Nutrition: Explain the Scientific Method and how scientists use various types of research studies and method to acquire nutrition information Definitions: Genome: the complete set of genetic material (DNA) in an organism or a cell. The study of genomes is called the genomics Nutritional Genomics: the science of how nutrients affect the activities of genes and how genes affect the interactions between diet and disease Anecdote: personal account of an experience or an event

Conducting Research Quantitative Research  Begins with a problem or a question (e.g. What food or nutrients may protect against the common cold?)  In search for an answer scientists make an hypothesis  Then conduct research studies to collect data that will test said hypothesis  Researchers deliberately manipulate one variable and measure any observed changes – as much as possible all the other variables are held constant Controls  Divide subjects into two groups – one group: experimental group receives manipulation while the other does not receive it  Observe both groups to see how both groups are affected  Make sure subjects have equal chance of being assigned to experimental or controlled group by randomization  The two groups of people must also be similar related to what is being tested Examples of Research Designs Epidemiological Research Studies- research incidence, distribution and control in a population Strengths- can narrow down the list of possible causes - Can raise questions to pursue through other research Limitations- cannot control variables that may lead to the development or prevention of a disease - Cannot prove cause and effect Study Definition Examples Many people in Cross-Sectional Researchers Studies observe how the Mediterranean much and what kinds of food a region drink more wine, eat more fat group of people eat and how from olive oil and yet low incidence healthy those people are. Their of heart disease than Northern findings identify factors that might Europeans and

Case- Control Studies

Cohort Studies

influence the incidence of a disease in various populations Researchers compare people who do and do not have a given condition such as a disease, closely matching them in age, gender and other key variables so that differences in other factors will stand out. These differences may account for the condition in the group that has it Researchers analyze data collected from a certain group of people (a cohort) at intervals over a certain period

North Americans

People will goiter lack iodine in their diets

Data collected periodically over past decades from more than 5000 people randomly selected from a town have revealed risk of heart attack increases as blood cholesterol rises Experimental Studies- test cause-and-effect relationships between variables Strengths – can control conditions (for most part) - Can determine effects of a variable - Can apply some findings on human beings to some groups of human beings

Limitations- cannot apply results from test tubes or animals to human beings - Cannot generalize findings on human beings to all human beings - Cannot use certain treatments for clinical or ethical reasons Study Definition Example Laboratory-Based Animal Researchers feed animals Mice fed a high fat diet Studies special diets that provide eat less food than mice or omit specific nutrients given a lower fat diet, so and then observe any they eat the same changes in health. Such number of kcals but the studies test possible mice eating the fat-rich disease causes and diet become severely treatments in a obese laboratory where all settings can be controlled. Laboratory-Based In Researchers examine Lab studies find that fish Vitro Studies effects of a specific oil inhibits the growth variable on a tissue, cell and activity of the or molecule isolated bacteria implicated in from a living organism ulcer formation Human Intervention (or Researchers ask people Heart disease risk factors Clinical) Trials to adopt a new behavior. improve when men These trials help receive fresh-squeezed determine the orange juice daily for 2 effectiveness of such months compared with interventions on the those on a diet low in development or Vitamin C—even when prevention of disease. both groups follow a diet high in saturated fat

Sample Size  To ensure chance of variation between two groups does not influence the results, the groups must be large Placebos  Taking anything believed to be beneficial may hasten recovery

 So the manipulation is given to both groups. The experimental group gets an actual manipulation while the control group gets a placebo manipulation – blind experiment because subjects not aware of what group they are in Double Blind  When both subjects and researchers don’t know, which group the subjects are in this is to prevent bias from the researcher Analyzing Research Findings - Scientists must be cautious about making conclusions until they have accumulated a body of evidence from multiple studies that have used various types of research designs - As evidence accumulates scientists become to develop a theory that uses the various findings and explains the complex relationships Correlation and Causes  Normally examine relationships between two or more variables and should be able to observe, verify or measure the variables selected  There could be no correlation, positive or negative depending on your findings – correlation evidence only proves that variables are associated not that one is the cause of the other  To find if one is the cause of the other scientists must find evidence of the mechanism – an explanation of how one variable might cause another Cautious Conclusions  When scientists draw conclusions careful not to generalize findings to all people and statements are always worded cautiously—may, some Publishing Research - Findings from research study are submitted to board of reviewers composed of other scientists who evaluate the study to make sure the scientific method was followed – peer review - Also, note the funding source because sometimes the funding source biases the study - Validity: conclusions are supported by the findings - Findings must be confirmed or disapproved by replication – through repeated tests

Qualitative Research - Use general research questions that seek to understand people’s real world perspectives and experiences – use methodical and analytical approaches - Have their work peer reviewed and often present their findings to people who participated in their research - Usually recruit a small number of participants to gain a deep understanding of how and why a certain phenomenon occur 1.4Dietary Reference Intakes: Define the Categories of the DRI and explain their purposes - Using results of thousands of research studies, nutrition experts have produced a set of standards that define the amounts of energy, nutrients, other dietary components and physical activity that best support health – these are called Dietary Reference Intakes (DRIs) Definitions Estimated Average Requirement: the average daily number of nutrients that will maintain a specific biochemical or physiological function in half the healthy people of a given age and gender group Recommended Dietary Allowance: the average daily amount of nutrient considered adequate to meet the known nutrient needs of practically all healthy people Deficient: nutrient amount that fails to meet the body’s needs and eventually results in deficiency symptoms Establishing Nutrient Recommendations - The recommendations provided by the people on DRIs committee apply to healthy people and may not be appropriate for people with diseases that decrease or increase nutrient needs How the committee goes about establishing the values that make up the DRI: 1. Estimated Average Requirements (EAR) 2. Recommended Dietary Allowances (RDA) 3. Adequate Intakes (AI) 4. Tolerable Upper Intake Levels (UL) Estimated Average Requirements (EAR)  Committee reviews thousands of studies to determine the requirement of a nutrient—how much is needed in the diet.  The committee selects a different criterion for each nutrient based on its roles in supporting various activities in the body and in reducing risks

 Each person’s body is unique so these recommendations differ between males and female, and change as you grow older. Therefore the committee clusters its recommendations into groups based on age and gender  This is how the committee determines an Estimated Average Requirement for each nutrient – the average amount that appears sufficient for half the population Recommended Dietary Allowances (RDA)  Once a nutrient requirement is established, the committee must decide what intake to recommend for everybody – the RDA  The EAR is probably closest to everybody’s need, however if everyone consumed exactly the average requirement of a given nutrient every day, half the population would develop deficiencies to the nutrient.  Recommendations are set high enough above the EAR to meet the needs of most healthy people – Small amounts above the daily requirement do no harm whereas amounts below the requir...