The Role of Nutrition in Our Health

© 2011 Pearson Education, Inc.

1The Role of

Nutrition in Our Health


What Is Nutrition?

• Food refers to plants and animals we eat

• Nutrition is the science that studies food:• How food nourishes our bodies• How food influences our health


Why Is Nutrition Important?

• Proper nutrition supports wellness• Wellness is more than the absence of disease• Physical, emotional, and spiritual health• Active process

• Critical components of wellness• Nutrition• Physical activity



• Healthful diet can prevent disease• Poor nutrition causes deficiency diseases:

scurvy, pellagra• Nutrition plays a role in osteoporosis and

cancer• Nutrition is associated with chronic diseases:

heart disease, stroke, and diabetes



Obesity is a growing problem:• Eating more calories than expended• Risk factor for heart disease, stroke, type 2

diabetes, and some forms of cancer



• Nutrition is a national goal to promote optimal health and disease prevention

• Goals of Healthy People 20201. Increase quality and years of healthy life2. Eliminate health disparities



What Are Nutrients?

• Nutrients are chemicals in foods that our bodies use for growth and function

• Organic nutrients contain carbon, an essential component of all living organisms• Carbohydrates, lipids, proteins, vitamins

• Inorganic nutrients: nutrients that do not contain carbon• Minerals and water


Determining Nutrient Needs

• Dietary Reference Intakes (DRIs): updated nutritional standards• Expanded on the traditional RDA values• Set standards for nutrients that do not have RDA

values• Dietary standards for healthy people only• Aim to prevent deficiency diseases and reduce

chronic diseases



Dietary Reference Intakes (DRIs) consist of:1. Estimated Average Requirement (EAR)2. Recommended Dietary Allowance (RDA)3. Adequate Intake (AI)4. Tolerable Upper Intake Level (UL)

Dietary Reference Intakes (DRIs) Determination



• Estimated Average Requirement (EAR)• The average daily intake level of a nutrient to

meet the needs of half of the healthy people in a particular life stage or gender group

• Used to define the Recommended Dietary Allowance (RDA) of a nutrient



• Recommended Dietary Allowance (RDA)• The average daily nutrient intake level that meets

the needs of 97% to 98% of healthy people in a particular category



• Adequate Intake (AI)• Recommended average daily nutrient intake level• Based on observed and experimentally

determined estimates of nutrient intake by a group of healthy people

• Used when the RDA is not available: calcium, vitamin D, vitamin K, and fluoride



• Tolerable Upper Intake Level (UL)• Highest average daily nutrient intake level likely to

pose no risk of adverse health effects to most people

• Consumption of a nutrient at levels above the UL increases the potential for toxic effects and health risks increases



• Estimated Energy Requirement (EER)• Average dietary energy intake to maintain energy

balance in a healthy adult• Defined by age, gender, weight, height, and level

of physical activity



• Acceptable Macronutrient Distribution Ranges (AMDR)• Ranges of energy intakes from macronutrients

that are associated with reduced risk of chronic disease while providing adequate intakes of essential nutrients

• If nutrient intake falls outside this range, there is a potential for increasing our risk for poor health



Assessing Nutritional Status

• Nutrition professional must have a thorough understanding of the client’s current nutritional status• Weight• Ratio of lean body tissue to body fat• Intake of energy and nutrients

• Foundation of recommended dietary and lifestyle changes

• Baseline for evaluation


Malnutrition

• Nutritional status is out of balance: too much or too little of a particular nutrient or energy over a significant period of time

• Undernutrition: too little energy or too few nutrients over time, causing weight loss or a nutrient-deficiency disease

• Overnutrition: too much energy or too much of a given nutrient over time, causing obesity, heart disease, or nutrient toxicity


Physical Examinations

• Physical exams are conducted by trained healthcare providers

• Tests depend upon client’s medical history, disease symptoms, and risk factors

• Typical tests include vital signs, lab tests, heart and lung sounds

• Nutritional imbalances may be detected by examining hair, skin, tongue, eyes, and fingernails


Health History Questionnaire

• Tool to assist in cataloging history of health, illness, drug use, exercise, and diet

• Socioeconomic factors (education, access to shopping/cooking facilities, marital status, ethnic/racial background)

• Energy and nutrient intake questionnaires


Dietary Intake Tools

• Techniques to assess nutrient and energy intakes: • Diet history• Twenty-four-hour dietary recall• Food frequency questionnaire• Diet records

• Strengths and limitations


Diet History

• Information from interview or questionnaire:• Weight (current and usual weight, goals)• Factors affecting appetite and food intake• Typical eating pattern • Disordered eating behaviors (if any)• Education and economic status• Living, cooking/food purchasing arrangements• Medication and dietary supplements• Physical activity


Twenty-Four-Hour Dietary Recalls

• Recalls all food and beverages consumed in the previous 24-hour period

• Accurate recall includes serving sizes, food preparation methods, and brand names of convenience foods or fast foods

• Limitations:• May not be typical intake• Relies on memory • Relies on ability to estimate portion sizes


Food Frequency Questionnaires

• Determine typical dietary pattern over a predefined period of time

• Include lists of foods with the number of times these foods are eaten

• Some assess only qualitative information (typical foods without amounts)

• Semiquantitative questionnaires assess specific foods and quantity consumed


Diet Records

• List of all foods and beverages consumed over a specific time period (3−7 days)

• Improved accuracy when:• Foods are weighed or measured• Labels of convenience foods and supplements

are saved• Challenges to accuracy and sufficient detail


Anthropometric Assessment

• Common measurements include height, body weight, head circumference in infants, and limb circumference

• Require trained personnel and correct tools• Compare standards specific for age/gender• Assess trends in nutritional status/growth


Nutrition Deficiencies

• Primary deficiency occurs when a person does not consume enough of a nutrient, a direct consequence of inadequate intake

• Secondary deficiency occurs when:• A person cannot absorb enough of a nutrient in

his or her body• Too much of a nutrient is excreted from the body• A nutrient is not utilized efficiently by the body


Deficiency Symptoms

• Subclinical deficiency occurs in the early stages; few or no symptoms are observed

• Covert symptoms are hidden and require laboratory tests or other invasive procedures to detect

• Symptoms of nutrition deficiency that become obvious are overt


Scientific Method

To ensure that certain standards and processes are used in evaluating claims, the researcher:

1. Makes an observation and describes a phenomenon

2. Proposes a hypothesis (educated guess) to explain the phenomenon

3. Develops an experimental design to test the hypothesis

4. Collects and analyzes data to support or reject the hypothesis


Scientific Method

• If the data are rejected, an alternative hypothesis is proposed and tested

• If the data support the original hypothesis, a conclusion is drawn

• The experiment must be repeatable, so other researchers can obtain similar results


Well-Designed Experiment

• The sample size (number of people being studied) should be adequate enough to ensure that the results obtained are not due to chance alone

• A control group is essential to comparison between treated and untreated individuals

• Control for other variables to avoid coincidentally influencing the results


Advancing a Theory

• A hypothesis that is supported by repeated experiments may be called a theory

• A theory represents a scientific consensus (agreement) of why the phenomenon occurs

• Theories can be challenged and changed as scientific knowledge evolves


Epidemiological Studies

• Also known as observational studies:• Involve assessing nutritional habits, disease

trends, or other health phenomena of large populations

• Determine the factors that may influence these phenomena


Model Systems

• Human studies:• Difficult to control for all of the variables • Humans have long life spans

• Animal studies • Preliminary information for designing and

implementing human studies • Research that cannot be done with humans • Drawbacks: results may not apply directly to

humans; ethical implications of animal studies


Human Studies

• Case control studies are epidemiological studies done on a smaller scale • Compare a group of individuals with a particular

condition to a similar group without this condition

• Clinical trials are controlled experiments • Experimental group receives the intervention• Control group is not given the intervention


Double-Blind, Placebo-Controlled Study

• Most likely to produce valid, reliable data • Blinding • Neither researchers nor participants know

which group is really getting the treatment• Helps prevent the researchers from seeing only

the results they want to see

• Placebo: imitation treatment that has no scientifically recognized therapeutic value • Psychosomatic effect or placebo effect


Evaluating Media Reports

• Discerning truth or fallacy:• Who is reporting the information?• Who conducted the research; who paid for it? • Is the report based on reputable research

studies? • Is the report based on testimonials? • Are the claims too good to be true?

• Quackery: misrepresentation of a product, program, or service for financial gain


Trustworthy Nutrition Experts

• Registered dietician (RD)• Licensed dietician meets the credentialing

requirements of a given state• Nutritionist has no legal definition • Professional with advanced nutrition degree

(master’s—MS, MA; doctoral—PhD)• Physician


Government Information Sources

• Centers for Disease Control and Prevention (CDC)

• National Health and Nutrition Examination Survey (NHANES)

• Behavioral Risk Factor Surveillance System (BRFSS)

• National Institutes of Health (NIH)


Reliable Nutrition Information

• American Dietetic Association• American Society for Nutrition Sciences• Society for Nutrition Education• American College of Sports Medicine• North American Association for the Study of

Obesity

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The Role of Nutrition in Our Health

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