Transcript Chapter 1

1
The Role of
Nutrition in Our
Health
© 2011 Pearson Education, Inc.
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
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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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Why Is Nutrition Important?
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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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Why Is Nutrition Important?
Obesity is a growing problem:
• Eating more calories than expended
• Risk factor for heart disease, stroke, type 2
diabetes, and some forms of cancer
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Why Is Nutrition Important?
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Nutrition is a national goal to promote
optimal health and disease prevention
Goals of Healthy People 2020
1. Increase quality and years of healthy life
2. Eliminate health disparities
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
What Are Nutrients?
• Macronutrients are nutrients required in
relatively large amounts
• Provide energy to our bodies
• Carbohydrates, lipids, proteins
• Alcohol is not considered a nutrient
• Does not support the regulation of body
functions or the building or repairing of tissues
• Considered to be both a drug and a toxin
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Carbohydrates
• Primary source of fuel for the body, especially
for neurologic functioning and physical
exercise
• Composed of chains of carbon, hydrogen, and
oxygen
• Found in grains (wheat, rice), vegetables,
fruits, legumes (lentils, beans, peas), seeds,
nuts, and milk products
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Lipids
• Insoluble in water
• Include triglycerides, phospholipids, and
sterols
• Composed of carbon, hydrogen, and oxygen
• Energy source during rest or low- to
moderate-intensity exercise
• Stored as adipose tissue (body fat)
• Provide fat-soluble vitamins
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Proteins
• Proteins are found in many foods, primarily in
meat, dairy, seeds, nuts, and legumes
• Small amounts of proteins are also found in
vegetables and whole grains
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Vitamins
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Vitamins are organic molecules that assist
in regulating body processes
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Critical in building and maintaining healthy
bones and tissues
Support immune system
Ensure healthy vision
Do not supply energy to our bodies
Vitamins are micronutrients, required in
smaller amounts
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Minerals
• Minerals are inorganic substances required
for body processes
• Regulate fluid and energy production.
• Essential for bone and blood health
• Remove harmful metabolic by-products
• Our diets and bodies contain major
minerals and trace minerals
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Water
• Water is an inorganic essential nutrient
• Water is involved in many body processes:
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Fluid balance and nutrient transport
Nerve impulses
Body temperature
Muscle contractions
Nutrient transport
Excretion of waste products
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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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
Dietary Reference Intakes (DRIs) consist of:
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Estimated Average Requirement (EAR)
Recommended Dietary Allowance (RDA)
Adequate Intake (AI)
Tolerable Upper Intake Level (UL)
Dietary Reference Intakes
(DRIs) Determination
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
Determining Nutrient Needs
• 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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
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
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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 nutrientdeficiency disease
• Overnutrition: too much energy or too much of a
given nutrient over time, causing obesity, heart
disease, or nutrient toxicity
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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
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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
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Dietary Intake Tools
• Techniques to assess nutrient and energy
intakes:
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Diet history
Twenty-four-hour dietary recall
Food frequency questionnaire
Diet records
• Strengths and limitations
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Diet History
• Information from interview or questionnaire:
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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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
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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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
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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
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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
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
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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
© 2011 Pearson Education, Inc.
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
© 2011 Pearson Education, Inc.
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
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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
© 2011 Pearson Education, Inc.
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)
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Reliable Nutrition Information
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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
© 2011 Pearson Education, Inc.