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An Overview of Nutrition

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					     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:

  •   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
    •   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
  –   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            This 144-gram breakfast
delivers 500 kcal, for an energy   delivers 500 kcal, for an energy
density of 1.1                     density of 3.5
(500 kcal/450 g = 1.1 kcal/g)      (500 kcal/144 g = 3.5 kcal/g)
Nutrients and Their Functions
             Other Nutrients
• Vitamins
  –   Organic
  –   Not energy-yielding
  –   Essential nutrient
  –   Water-soluble vs. fat-soluble
  –   Vulnerable to destruction
• Minerals
  –   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
•   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
  1.   Who runs the site?
  2.   Who pays for the site?
  3.   What is the purpose of the site?
  4.   Where does the information come from?
  5.   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:
  1.   What is the World Food Day
  2.   Who/what organization founded it
  3.   What year was it founded
  4.   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.

				
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Jun Wang Jun Wang Dr
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