Transcript Document 7447073

Chapter 1
An Overview of Nutrition
Chapter Objectives
• Identify the six classes of nutrients and
determine which are energy-yielding nutrients.
• List four factors that affect our food choices.
• Explain why meeting nutrient needs by eating a
well-balanced diet is a healthier choice than
relying on supplements.
• Describe the steps of the scientific method.
• Discuss the three different types of research that
scientists can use to test their hypothesis.
• List several factors to consider when obtaining
nutrition information on the internet.
Overview of Nutrition
•Nutrition
–Science of foods and the substances they contain, their
actions within the body
•Foods
–from plants or animal sources
–Provide energy and nutrients
–Used by the body for maintenance, growth, and repair
•Diet
–The foods one consumes.
–The quality of which affects the risk of chronic
diseases
What Drives Our Food Choices?
We choose foods for many other reasons beyond the
basic need to obtain nutrients:
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Taste
Ethnic heritage or tradition
Social interactions
Advertising
Availability, Convenience, and Economy
Habits
Emotional Comfort
Body Weight and image
Nutrition and Health Benefits
The Nutrients
We need to eat and drink to obtain:
– Nutrients: chemical compounds in foods to
provide fuel for energy (measured in
kilocalories), growth, maintenance and to
regulate body processes
• Six classes: carbohydrates, fats, protein, vitamins,
minerals, water
– Energy: The capacity to do work. The
energy in food is chemical energy, it can be
converted to mechanical energy in the body.
• Food energy is measured in calories
Meet the Nutrients
Six classes of Nutrients
• Water
• Carbohydrates
• Protein
• Fat
• Vitamins
• Minerals
The Nutrients
• Chemical composition of Nutrients
– Organic – contain carbon
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Carbohydrate
Protein
Lipids
vitamins
– Inorganic – do not contain carbon
• Water
• minerals
The Nutrients
Essential nutrients
• Nutrients a person must obtain from food
because the body cannot make them for
itself in sufficient quantity to meet
physiological needs.
Energy yielding nutrients (Macronutrients)
• The nutrients that break down to yield
energy the body can use
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Carbohydrate
Fat
Protein
Energy-Yielding Nutrients
Calories and kilocalories
• Calories are units by which energy is
measured. Food energy is measured
in kilocalories (kcal)
– Carbohydrate = 4 kcal/gram
– Protein = 4 kcal/gram
– Fat 9 = kcal/gram
Energy from Foods
Energy density – a measure of the energy a
food provides relative to the amount of
food (kcal per gram)
• Lower energy density – provides low kcal
per gram
• Higher energy density - provides high kcal
per gram
Lower energy density
Higher energy density
This 450-gram breakfast
delivers 500 kcal, for an energy
density of 1.1
(500 kcal/450 g = 1.1 kcal/g)
This 144-gram breakfast
delivers 500 kcal, for an energy
density of 3.5
(500 kcal/144 g = 3.5 kcal/g)
Nutrients and Their Functions
Other Nutrients
• Vitamins
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Organic
Not energy-yielding
Essential nutrient
Water-soluble vs. fat-soluble
Vulnerable to destruction
• Minerals
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Inorganic
Not energy-yielding
Essential nutrient
Indestructible
• Water
– Inorganic
– Not energy-yielding
– Essential nutrient
Dietary Reference Intakes (DRI)
Estimated Average Requirements -(EAR)
• defines the requirement of a nutrient that
supports a specific function in the body for
half of the healthy population.
Recommended Dietary Allowances – (RDA)
• use the EAR as a base
• include sufficient daily amounts of
nutrients to meet the known nutrient needs
of all healthy populations.
• This recommendation considers
deficiencies.
Dietary Reference Intakes
• Adequate Intakes (AI)
– reflect the average daily amount of a nutrient
without an established RDA that appears to be
sufficient.
• Tolerable Upper Intake Level (UL)
– is a maximum daily amount of a nutrient that
appears safe for most healthy people and
beyond which there is an increased risk of
adverse health effects.
Energy Recommendations
• Estimated Energy Requirement –EER
– average daily energy intake to maintain energy
balance and good health for population groups.
• Acceptable Macronutrient Distribution
Ranges (AMDR)
– range of intakes for energy nutrients that provide
adequate energy and nutrients and reduce risk of
chronic disease.
– Carbohydrate: 45% - 65%
– Fat: 20% - 35%
– Protein: 10% - 35%
• RDA –
– Protein - .8g/kilogram
– Based on weight
Facts about the Recommendations
• Estimates of adequate energy apply to healthy
people
• Not optimal intakes for all individuals
• Nutrients are intended to be met through variety
of foods
• Recommendations apply to average daily
intakes
• DRI serve a unique purpose – to keep
population healthy and prevent chronic diseases
– EAR – is for groups
– RDA – for individuals
Nutrition Assessment
What happens When a Person Doesn’t Get
Enough or Gets Too much of a nutrient or
energy?
• Malnutrition – Any condition caused by
deficiency or excess food energy or
nutrient intake over time.
• Undernutrition – Deficient energy or
nutrients.
• Overnutrition – Excess energy or nutrients
Nutrition Assessment of Individuals
Evaluates the many factors that influence or
reflect nutritional health.
• Historical information regarding diet, health
status, drug use, and socioeconomic status is
gathered.
• Anthropometric data measure physical
characteristics including height and weight.
• Physical examinations require skill and reveal
possible nutrition imbalances.
• Laboratory tests detect early signs of
malnutrition.
Nutrition Assessment of
Individuals
Stages in Nutrient Deficiency (example is given
for iron)
• Overt is easy to observe
• Primary deficiency is inadequate dietary
intake
• Secondary deficiency is caused by disease
or drugs
• Sub-clinical deficiency is the early stages of
deficiency without outward signs
• Covert is hidden
Nutrition Assessment
of Populations
• National nutrition surveys
– National Nutrition Monitoring Program uses survey
research to collect data on foods people eat and people’s
health status.
– Data collected is used for nutrition policy, food assistance
programs and food supply regulation
• National health goals
– Healthy People is a national public health initiative under
the U.S. Department of Health and Human Services that
is published every 10 years.
– Identifies the most significant threats to health
– Focuses efforts on eliminating these threat
Nutrition Assessment
of Populations
Diet and Health
Diet and Health
How Does the Average
American Diet Stack Up?
Average American diet is high in:
– Sodium
– Saturated fat
– Calories
Average American diet is low in:
– Vitamin E
– Calcium
– Fiber
How Does the Average
American Diet Stack Up?
Incidence of overweight and obesity is on
the rise.
– 65% of American adults and 15% of children
(ages 6 to 19) are overweight
– Take in more calories than needed
– Burn fewer calories due to sedentary
lifestyles
– Resulting in increased rate of type 2 diabetes
(especially children), heart disease, cancer,
and stroke
Obesity Trends Among U.S.
Adults
Figure 1.3
The Science of Nutrition
• Observational Research: involves
looking at factors in two or more groups of
subjects to see if there is a relationship to
certain health outcomes
• Epidemiological research: study of
populations of people
• Example: Relationship of sun exposure and
incidence of rickets in Norway compared with
Australia
– May be due to other unidentified diet or lifestyle factors
The Science of Nutrition
• Experimental Research: involves at
least two groups of subjects
– Experimental group: given a specific
treatment
– Control group: given a placebo (“sugar pill”)
– Double-blind placebo-controlled experiment is
“gold standard.”
• Neither scientists nor subjects know which group is
receiving which treatment.
• All variables held the same and controlled for both
group.
• Sample size – number of people in the study.
The Science of Nutrition
• Hypothesis – an educated guess to
answer a question. For example: “what
foods or nutrients might protect against
hypertension?” The hypothesis = “Foods
low in sodium and high in potassium help
reduce risk of hypertension”
Controlled
Experiments:
Scientists use
experimental
research to
test
hypotheses.
Figure 1.6
What’s the Real Deal When It
Comes to Nutrition Research and
Advice?
Newspaper headlines and television news
items report results of a single, recent
research study.
Advice from authoritative health and nutrition
organizations is based on:
– Consensus: the opinion of group of experts
based on collection of information
Evaluating Media Headlines
with a Critical Eye
Before making dietary and lifestyle changes based on
media reports, read with a critical eye and ask:
– Was the research finding published in a peer-reviewed
journal?
– Was the study done using animals or humans?
– Do the study participants resemble me?
– Is this the first time I’ve heard about this?
Wait until research findings are confirmed and
consensus reached by reputable health
organizations before making changes.
Quackwatchers
Beware of health quackery and fraud:
– Promotion and selling of health products and
services of questionable validity
– Sales people introduce health fears and
make false nutrition claims and unrealistic
promises and guarantees.
– http://quackwatch.org helps consumers
identify quackery and fraud.
You Can Trust the Advice of
Nutrition Experts
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Registered Dietitian (RD): completed at least a
bachelor’s degree at an accredited U.S. college or
university and a supervised practice, passed a national
exam administered by the American Dietetic Association
Public Health Nutritionist: has degree in nutrition but
may not be an RD (if didn’t complete supervised
practice, not eligible to take ADA exam)
Professionals holding advanced degrees in nutrition
Licensed dietitian (LD): licensed by state licensing
agencies
Obtaining Accurate Nutrition
Information on the Internet
National Institutes of Health (NIH) 10
Questions to consider when viewing a
health-related website
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Who runs the site?
Who pays for the site?
What is the purpose of the site?
Where does the information come from?
What is the basis of the information?
Obtaining Accurate Nutrition
Information on the Internet
6. How is the information selected?
7. How current is the information?
8. How does the site choose links to other
sites?
9. What information does the site collect about
you and why?
10. How does the site manage interactions with
visitors?
Homework
For 5 point extra credit, provide answers to the
following questions:
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4.
What is the World Food Day
Who/what organization founded it
What year was it founded
What is the theme for 2007
Complete a family Health History worksheet
Bring a food label to class next time
• The food label must be a food that contains
nutrients (Kcal, fat & protein)
Must be submitted next class. No exceptions.