Introduction to Nutrition Science Chapter 1

SMHM 2460 Introduction to Nutrition Science
Textbook: Thompson J & Manore M. Nutrition an Applied Approach. San Francisco: Pearson Benjamin Cummings; 2009. Chapter 1: The Role of Nutrition in Our Health What is Nutrition? Nutrition is about us and our relationship with food. It is the science that studies foods: how foods nourish our bodies, and influence our health. The study of nutrition encompasses the consumption, digestion, metabolism, and storage of nutrients and their affect on us as well as factors that influence our eating habits, amounts we eat, and safe handling of foods. The science of nutrition grew out of work linking nutrient deficiencies to specific illnesses. Why is Nutrition Important? Nutrition is one of several factors that contribute to wellness a multidimensional state of being that encompasses physical, emotional, social, occupational, and spiritual health. Sound nutritional practices are inseparable from adequate physical activity. A Healthful Diet Can Prevent Some Diseases and Reduce Risk for Others Recognition of the link between certain illnesses, such as scurvy, rickets, and pellagra, and nutritional status was the impetus for establishing recommendations for the general population. Healthful diets can reduce risk of chronic disease that develops slowly over a period of time. Evidence is growing that a link exists between poor lifestyle choices, including counterproductive eating habits and lack of physical exercise, and incidence of chronic disease including some among the ten leading causes of death in the US. The Center for Disease Control and Prevention FastStats lists major causes of death in the US.

Ten Leading Causes of US Death Year 2006 in Descending Order of Predominance 1 Heart disease 2 Cancer 3 Stroke (cerebrovascular disease) 4 Chronic lower respiratory disease 5 Accidents 6 Diabetes 7 Alzheimer’s disease 8 Influenza and pneumonia 9 Nephritis, nephritic syndrome, nephrosis 10 Septicemia 1 Cause of Death FastStats at http://www.cdc.gov/nchs/FASTATS/lcod.htm

1

Read and compare: Is this list the same as that in your textbook? Why might there be a difference?

P. Connors, PhD, RD University of North Texas

2
The Center for Disease Control and Prevention Tracks Trends in Obesity

2008 State Obesity Rates as a Percentage of the Population State Alabama Alaska Arizona Arkansas California Colorado Connecticut Delaware Washington DC Florida Georgia Hawaii Idaho
1

1

% 31.4 26.1 24.8 28.7 23.7 18.5 21.0 27.0 21.8 24.4 27.3 22.6 24.5

State Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Michigan Minnesota Mississippi Missouri

% 26.4 26.3 26.0 27.4 29.8 28.3 25.2 26.0 28.9 24.3 32.8 28.5

State Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania

% 23.9 26.6 25.0 24.0 22.9 25.2 24.4 29.0 27.1 28.7 30.3 24.2 27.7

State Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming

% 21.5 30.1 27.5 30.6 28.3 22.5 22.7 25.0 25.4 31.2 25.4 24.6

Massachusetts 20.9

US Obesity Trends by State 2008 at http://www.cdc.gov/obesity/data/trends.html#State

Read and Compare: The US maps (figure 1.2) in your textbook track obesity from 1985-2005. Compare the maps in your textbook to the 2008 map (above). Are trends consistent for all states? Why might some states experience a change in the obesity trend?

P. Connors, PhD, RD University of North Texas

3
What are Nutrients? The foods that you eat are made up of chemicals, some of which are used by the body to regulate function and build tissues. Those chemicals that are necessary and without which the body cannot function are essential. These essential chemicals are nutrients. There are six nutrient groups: (1) carbohydrate (2) fat/oil (3) protein (4) vitamin (5) mineral (6) water A nutrient that contains carbon is classified as organic. Carbon is an essential part of all living things. Carbohydrate, fats/oils, protein, and vitamins all contain carbon. Minerals do not contain carbon and are classified as inorganic. What is a kilocalorie? Energy provides living beings with the capacity to do work. The energy that your body uses everyday is derived from foods in your diet that contain carbohydrate, protein, and fats/oils. A kilocalorie (kcal) is the amount of heat required to raise the temperature of 1 kilogram of pure water 1o Celsius. The kilocalorie allows us to quantify or measure energy in food in a standardized way. In common practice, as displayed on the Nutrition Facts Label of packaged food, people call food energy as “calories” when they really mean kilocalories. The only nutrients that provide energy are carbohydrate, fats/oils, and protein. These nutrients are needed in large amounts and as a result are called macronutrients. Although alcohol does contain calories, it cannot regulate body function or support repair and maintenance of tissue. In fact the body handles alcohol (ETOH) as a toxin. Calculating Nutrient Energy Values

Nutrient kcal/gram Carbohydrate 4 Fat 9 Protein 4

P. Connors, PhD, RD University of North Texas

4
Time to Practice!

Fill in the Blank Nutrition Facts for Frozen Pizza

Kcal/g Total Fat 11 g 9 Total Carbohydrate 35 g 4 Protein 14 g 4 Calculate the kilocalories in a packaged food item 1. Determine number of calories provided by each energy nutrient 2. Multiple grams by kcal/g, for example, Total Fat = 11 g *9 g/kcal = 99 kcal 3. Determine how many calories are in a serving 4. Total calories = kcal carbohydrate + kcal fat + kcal protein 5. Determine percent calories from fat 6. Calories from fat = kcal fat/total kcal Think about it: If you ate the whole pizza, how many kilocalories would you consume? Carbohydrates are a Primary Fuel Source Carbohydrates contain carbon, hydrogen and oxygen. Historically carbohydrates (rice, wheat, potatoes, corn) provided the energy upon which civilizations rose. The RDA (Recommended Dietary Allowance) for healthy adults is 130 grams/day. This minimum amount optimizes brain function and energy production in cells. Most people easily meet and exceed this recommendation. Fats Provide Energy and Other Essential Nutrients Fats and oils are lipids, a group of water‐repelling substances that also includes cholesterol. Fats are composed of carbon, hydrogen, and oxygen with a smaller proportion of oxygen than carbohydrates. As a result fat molecules pack closely together and yield more energy per gram than carbohydrates. People are designed to store large amounts of fat in adipose tissue as a hedge against future deprivation. Fats are the most concentrated source of energy and the most economical for physiological storage. Fats are an important part of the diet as they contain several essential fatty acids that must be consumed to maintain good health, and are carriers for fat‐soluble vitamins such as vitamins A and D. Proteins Proteins are composed of building blocks called amino acids which contain carbon, hydrogen, oxygen, and nitrogen. Although protein is used by the body as a source of energy, it is not the primary source or most efficient one. Amino acids are used to manufacture substances, such as hormones and enzymes, that regulate body function, and to build and repair tissues. Proteins help maintain fluid balance and substances made from protein aid in digestion and transportation of nutrients.
P. Connors, PhD, RD University of North Texas

Serving size ½ pizza (140 grams) Calories Calories from Fat

5
Vitamins Assist in Regulation of Biological Processes Vitamins are organic compounds, or those that contain carbon. Although vital to energy production, in and of themselves vitamins do not contain energy. They assist in the release of energy from the three macronutrients: carbohydrate, fat, and protein. Needed in small amounts, vitamins are called micronutrients. There are two types of vitamins: fat‐ soluble, and water‐soluble. Solubility influences how a vitamin is absorbed, transported and stored in the body. Vitamins are essential as we are unable to manufacture them for ourselves, we must consume them in our diets to stay healthy. Minerals Assist in the Regulation of Many Body Functions Minerals do not contain carbon and are, therefore, inorganic. Minerals are not broken down or changed by the process of digestion nor when used by the body. Minerals maintain their structure regardless of where and how they are used. Minerals assist in maintenance of fluid balance and energy production. Classified as to amounts needed for health, minerals are described as either major or trace minerals. Water Water is, of course, inorganic. It is the universal solvent for physiological activities and is found both inside and outside body cells. Water is vital to nerve function, muscle contraction, nutrient transport, and excretion of wastes. Adequate intake of clean, safe water is critical throughout life. How Can I Figure Out My Nutrient Needs? Developed from a perspective of preventing nutrient deficiencies, dietary recommendations have evolved over time to include a focus on disease prevention and health maintenance. The Dietary Reference Intakes (DRIs) demonstrate a new focus on chronic disease risk reduction and the promotion of health and wellness. Dietary Reference Intakes are standards for healthy people and don’t apply to those who are ill or who are nutrient deficient. Estimated Average Requirement (EAR) Guides to Recommended Dietary Allowances EAR is the average daily nutrient intake that is estimated to meet requirement of ½ the healthy people in a particular life stage and gender group. If the EAR only meets the needs of ½ the population, final recommendations, by definition, will be higher. Recommended Dietary Allowance (RDA) Meets the Needs of Nearly All Healthy People RDAs are projected to meet the needs of 97‐98% of healthy people in a given life stage and gender group. EARs are established before RDAs are determined. Adequate Intakes (AI) Based on Estimates of Nutrient Intakes An AI is designated for a nutrient when research is inadequate to establish an RDA and more information is needed to establish needs. Tolerable Upper Intake Level (UL) is the Highest Level that Poses No Health Risk This daily nutrient intake level is the highest intake that has no risk of adverse health effects. Intakes above this level expose an individual to risk from toxic side effects of excessive nutrient intake.
P. Connors, PhD, RD University of North Texas

6
Estimated Energy Requirement (EER) is the Intake Predicted to Maintain a Healthy Weight The EER is the average dietary energy consumption that maintains energy balance in a healthy person. The EER is individualized based upon energy intake and expenditure, physical activity, age, gender, weight, height, and state of health. Check it out! Read more about how estimated energy requirements are calculated at http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1784117 Acceptable Macronutrient Distribution Ranges (AMDRs) Are Associated With Reduced Risk of Chronic Disease The AMDRs are a range of energy intakes associated with a reduced risk of chronic disease and that provide adequate energy for essential body function. AMDRs are expressed as a percent of total energy intake with upper and lower boundaries. Time to Practice! Review Dietary Reference Intakes Macronutrients at the following link to complete the chart below: http://www.iom.edu/Object.File/Master/7/300/Webtablemacro.pdf Dietary Reference Intakes Macronutrients1 Nutrient Years Gender RDA AMDR Carbohydrate 9‐13 male female 19‐30 male female Total Fiber 4‐8 male female 19‐30 male female Total Fat 1‐3 child 31‐50 male female Saturated Fat all ages either Protein 9‐13 male female 14‐18 male female
1

Dietary Reference Intakes Macronutrients at http://www.iom.edu/Object.File/Master/7/300/Webtablemacro.pdf Think about it! Not all macronutrients have both RDA and AMDR for every life stage. Why might this be the case? Why are protein recommendations for males and females different?

P. Connors, PhD, RD University of North Texas

7
Research Study Results: Who Can We Believe? Research involves the scientific method. In reviewing any research results that you found in the popular media, consider if enough evidence is presented to substantiate a claim. There is a standardized method for investigating a phenomenon, and it is the scientific method. Steps in the Scientific Method 1. Make an observation or describe a phenomenon 2. Propose a hypothesis that explains the phenomenon 3. Craft an experimental design: a plan to systematically test the hypothesis 4. Collect and analyze data in a structured manner that others can replicate 5. Determine if results support or reject the relationship described in the hypothesis 6. If the hypothesis is accepted, draw conclusions 7. If the hypothesis is rejected reexamine the phenomenon and consider alternate hypotheses 8. Experiment repeated to confirm results 9. Based on successful replication a theory is proposed The observation of a phenomenon initiates a question concerning the relationship between two variables or concepts. A hypothesis is a proposed explanation for the observed phenomenon that is written in such a manner that it is testable, i.e. can be measured. Good hypotheses are unbiased and hold up under repeated testing. An experimental design is a systematic approach to a scientific study that tests a hypothesis. A study has a sample drawn from the population of interest. Relevant to the reliability of results is the size of the sample, its ability to accurately represent the population, the inclusion of a control and intervention group, and management of extraneous variables that might influence results in an unpredictable way. Data is collected and analyzed in a carefully monitored and standardized manner. Of importance to results is what type of data to collect and how to analyze it. Generally speaking, reliability in results is expressed as a confidence level, typically 95%. When first proposed, most hypotheses are too broad, imprecise, or difficult to measure. Repeat experiments lead to refined hypotheses that accurately measure the phenomenon of interest. A well‐designed experiment is repeatable – other researchers can replicate procedures and compare results to the original experiment. A research project that can’t be replicated is not valid! Theories develop following extensive research featuring multiple experiments that continue to support hypotheses that are refined and focused through testing.

P. Connors, PhD, RD University of North Texas

8
Types of Research Studies Epidemiological studies give us information about existing relationship but can’t speak to cause and effect. These are observational studies that report on health patterns and consequences of behaviors such as smoking, diets high in saturated fat, or sedentary life styles. Model Studies address the problem of experimental control in human studies by using animal and cell models to test medical treatments and drugs. Human studies are either case studies or clinical trials. A case study typically has a small sample in which participants with a specific health condition, such as type 2 diabetes, are compared to those without it to highlight factors contributing to the condition. Clinical trials are tightly controlled experiments designed to determine the effect of an intervention on a health condition or disease state. Validity of results is enhanced by random assignment of participants to either the control (non‐treatment) or manipulation (treatment) group. In a double blind design neither researcher nor participant knows who is assigned to which group. The purpose of this approach is to minimize personal bias in assignment and to avoid getting “expected” results. Think about it! What is the placebo effect? What is the effect of “knowing” about a treatment? Do you think that someone taking a supplement might have the “placebo effect” rather than a real change in health? Evaluating the media 1. Who is reporting, what is the training and area of expertise? 2. Who conducted the research and who paid for it? 3. Is the report based on work done by a recognized researcher? 4. Was the scientific method used in the research project? 5. Were results reported in scientific journals with references and researchers names? 6. Can you find the original study? 7. Was the report based on an unsubstantiated testimonial? 8. Is it too good to be true? What is quackery? It is the misrepresentation of a product, program, or service for financial gain. Studies Reported in the Media The Nurses’ Health Study – Harvard University http://www.channing.harvard.edu/nhs/ Join a Health Study or Clinical Trial http://www.niehs.nih.gov/research/clinical/join/index.cfm National Nutrition and Health Examination Survey http://www.cdc.gov/nchs/nhanes.htm

P. Connors, PhD, RD University of North Texas