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Introduction to Human Nutrition. Course Web Page. Real Hope for Haiti – Clinic for Malnourished Children. Chapter Outline. Nutrition defined Classifying the nutrients Nutritional research Nutrition and health Healthy People 2020 goals Hunger and appetite (next class)

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chapter outline
Chapter Outline
  • Nutrition defined
  • Classifying the nutrients
  • Nutritional research
  • Nutrition and health
    • Healthy People 2020 goals
  • Hunger and appetite (next class)
  • Factors impacting food choices
    • Small group exercise
nutritional goals
Nutritional Goals
  • Quality intake that allows you to function at your best and promotes health.
    • Intake that provides adequate levels of each nutrient
  • Quantity of intake that promotes a healthy body weight.
nutrition defined
Nutrition Defined
  • Nutrition – the science of foods and the nutrients they contain
  • Study the:
    • action of foods and the nutrients in the body
    • relationship between diet and health
nutrition defined6
Nutrition Defined
  • Actions in the body include:
    • Ingestion
    • Digestion
    • Absorption
    • Transport
    • Metabolism
    • Excretion
what s considered food
What’s Considered Food?
  • Foods contain nutrients and are derived from plant or animal sources
  • Nutrients are used by the body to provide energy and to support growth, maintenance and repair of body tissues
    • ~ 40 nutrients identified at this time
classifying nutrients
Classifying Nutrients

There are 6 Classes of Nutrients

1. Carbohydrates

2. Lipids (fats)

3. Proteins

4. Vitamins

5. Minerals

6. Water

describing the nutrients
Describing the Nutrients
  • There are several ways to classify the classes of nutrients.
    • Essential or nonessential
    • Organic or inorganic
    • Macronutrient or micronutrient
    • Energy yielding or not
classifying nutrients11
Classifying Nutrients
  • Essential nutrients– nutrients the body either cannot make or cannot make enough of to meet its needs.
    • These nutrients must be obtained from foods (ingested in some manner)
    • Examples:
      • Vitamins
      • Calcium, iron, and other minerals
      • Some of the amino acids
essential nutrients
Essential Nutrients
  • To be classified as an essential nutrient:
    • The biological function of nutrient is known
    • Omission from the diet leads to a decline in a biological function
    • Return of the nutrient restores the biological function
classifying nutrients13
Classifying Nutrients
  • Nonessential nutrients– body can make from other nutrients ingested

 Examples:

      • Cholesterol
      • Some amino acids
classifying nutrients by composition
Classifying Nutrients by Composition
  • Organic nutrients - contain carbon
      • Carbohydrates
      • Lipids
      • Proteins
      • Vitamins
  • Inorganic nutrients - do not contain carbon
      • Minerals
      • Water
quantity needed
Quantity Needed
  • Macronutrients: need in relatively large amounts
    • Carbohydrates, lipids, proteins
  • Micronutrients: need in relatively small amounts
    • All other nutrients
classifying nutrients16
Classifying Nutrients
  • Energy-yielding nutrients (3):
    • Carbohydrates
    • Fats (lipids)
    • Proteins
  • Where does the energy come from?
a little more on energy
A little more on energy
  • Measure energy in kilocalories in U.S.
    • What most think of as a “calorie” is really a kilocalorie
    • Kcal = amount of energy needed to raise the temperature of 1 kg of water by 10C
  • Measure energy in kilojoules (kJ) in most other countries
energy in the body
Energy in the Body
  • The body uses the energy yielding nutrients to fuel all activities
    • All energy yielding nutrients are “caloric”.
  • If more energy is ingested than is needed to fuel body activities the extra energy is stored as _________ and ________ occurs.
energy yielding nutrients20
Energy-Yielding Nutrients
  • Carbohydrates: C, H, O
    • 4 kcal/gram
    • Body’s primary source of energy
      • Use as glucose
      • Glucose is the brain’s only source of energy
    • Carbohydrate stores are limited ~12-24 hours (in liver and muscle)
classes of carbohydrates
Classes of Carbohydrates
  • Simple sugars
    • Monosaccharides and disaccharides
  • Complex carbohydrates
    • Starch
    • Fibers
  • Carbohydrate rich foods……..
  • Lipids – fats and oils: C, H, O
    • 9 kcal/gram
    • Body’s alternate source of energy
      • Use fat along with glucose as an energy source most of the time
    • Stores are unlimited
types of lipids
Types of Lipids
  • Fats – solids
  • Oils – liquids
  • Saturated (solids/fats)
    • No carbon to carbon double bonds
  • Unsaturated (liquids/oils)
    • Carbon to carbon double bond(s) present
  • Lipid rich foods?
  • Proteins: C, H, O, N, S
    • 4 kcal/gram (same as _______)
    • Body’s least desirable source of energy
      • WHY? …….
    • Protein is used for energy only when carbohydrate is NOT available as an energy source.
    • Protein rich foods?
energy yielding non nutrient
Energy-Yielding Non-nutrient
  • Alcohol – 7 kcal/gram
  • Non-nutrient because it interferes with growth, maintenance and repair of the body
    • Alcohol’s metabolites are harmful
energy density
Energy Density
  • Measure of the kcal per gram of food
  • _______ has the highest energy density of the 3 energy-yielding nutrients.
  • Foods with a high energy density provide more kcal per gram than low density foods.
evaluating a food label
Evaluating a Food Label
  • _____ grams carbohydrate
  • _____ grams fat
  • _____ grams protein
  • TOTAL KCAL: ____________
6 classes of nutrients
6 Classes of Nutrients
  • Carbohydrates
  • Lipids (fats and oils)
  • Proteins
  • Vitamins
  • Minerals
  • Water

Pages 8/9

  • Essential
  • Organic, micronutrient
  • Not energy-yielding
  • Can be water-soluble or fat-soluble


  • Essential
  • Inorganic, micronutrient
    • Major minerals: Ca, P, Na
    • Trace minerals: Fe, Zn
  • Not energy-yielding
  • Indestructible
  • Water (H2O)
    • Essential
    • Organic or inorganic?
    • Noncaloric
    • We are ~60% water
the science of nutrition
The Science of Nutrition
  • One of the newest sciences
    • New branch is nutritional genomics
      • Study of the interaction of nutrients with DNA/genes and how those genes impact health
  • Like all sciences, nutrition is based on scientific research
scientific method
Scientific Method
  • Observations  Questions
  • Hypotheses  Predictions
  • Test hypotheses/predictions
  • Analyze data and draw conclusions
  • Share results
observations and questions
Observations and Questions
  • Make observations about diet and health. These observations lead to questions

For example:

    • The incidence of breast cancer is much lower in Japan than in the U.S.
    • Diet in Japan is rich in…..while in U.S. diet is rich in ……
  • Question?:
develop hypotheses and make predictions
Develop Hypotheses and Make Predictions
  • Hypothesis – tentative explanation of the observations or answer to the question
  • Make prediction – If the hypothesis is true what else is true?
  • Conduct experiments to test the predictions
    • Easier said than done when people are involved!
    • We’ll consider research designs later/soon.
one experimental design
One Experimental Design
  • When possible, randomly assign subjects to either a control of experimental group
    • Goal is for two groups to be as similar to each other as possible
    • Control Group – either no change to diet or given a placebo
    • Experimental group – diet changed or given a supplement
experimental design
Experimental Design
  • Compare the health/lab values of the two groups before and after the diet change.
    • Example – DASH diet study
analyze results
Analyze results…
  • Analyze results
  • Draw conclusions about the validity of the hypothesis
  • Test alternate hypotheses
  • Share findings
    • Publish in nutritional journals
    • Present findings at conferences
common research designs
Common Research Designs
  • Epidemiological study (observe)
    • Cross-sectional
    • Longitudinal
    • Case-control study
  • Experimental (intervene)
    • Animal studies
    • Human clinical trials
      • Double blind study
    • Lab studies

page 25

the science of nutrition44
The Science of Nutrition

1. Epidemiological studies

  • Study of populations
  • Look for correlations between dietary practices and health
epidemiological studies
Epidemiological Studies

Cross-sectional - look for correlations between diet and health at a point in time

Longitudinal Studies - Follow a group of people (a cohort) over a period of time

  • Look for differences in diet that might account for the differences in health
epidemiological studies46
Epidemiological Studies
  • Case-control study – compare the diet of individuals with a condition to that of healthy individuals
    • Again, do not change their diet…..just observe it.
human experimental studies
Human Experimental Studies

Often called a Clinical Study

  • Randomly assign like people to either the experimental or control group
  • Alter the diet of experimental group as compared to a control group
  • Compare incidence of disease/lab values/ performance …. of two groups
types of clinical trials
Types of Clinical Trials
  • Blind experiments
      • Subjects do not know which group they are in
  • Double blind experiments
      • Neither subjects nor the researchers know which group the subjects are in until after the experiment is over
      • Goal is to avoid bias in the reporting/recording of the data.
experimental studies
Experimental Studies

Animal Studies

  • Controlled studies in lab setting using animals
  • Alter diet of experimental group
  • Compare health/lab values of control and experimental groups
  • Benefits? ….
  • Drawbacks? ……
experimental studies50
Experimental Studies

Lab-Based Studies

  • Also called in vitro studies
  • Examine impact of a substance on living tissue in a “test tube”


the science of nutrition52
The Science of Nutrition
  • Size matters
    • Good studies have relatively large sample sizes
    • Preliminary studies have smaller sample sizes
  • Peer review matters
    • Information in peer- reviewed research journals is much more credible than that in popular magazines, TV, Internet
diet and health
Diet and Health
  • Diet - the foods one consumes
      • The quality of your daily diet affects the risk of chronic diseases
        • Meaning…..The food choices you make daily have a cumulative impact on your health
nutrition and health
Nutrition and Health
  • Chronic health issues associated with diet include:
    • Heart disease
    • Hypertension
    • Obesity
    • Type II Diabetes
    • Osteoporosis
    • See pages 4/5
improving your health
Improving your Health
  • Goal is to reduce the number of risk factors that are in your control
    • Risk factor = something that statistically increases the incidence of a disease
      • Risk factors may not be the cause of the disease
leading causes death us
Leading Causes Death - US
  • Heart disease: 616,067
  • Cancer: 562,875
  • Stroke: 135,952
  • Chronic respiratory diseases: 127,924
  • Accidents (unintentional injuries): 123,706
  • Alzheimer's disease: 74,632
  • Diabetes: 71,382
  • Influenza and Pneumonia: 52,717
  • Kidney disease: 46,448
  • Septicemia: 34,828 CDC, 2009
improving health
Improving Health
  • Risk factors in your control:
    • Smoking
    • Alcohol intake
    • Over-consumption of calories
    • Physical inactivity
    • Poor quality diet
improving health58
Improving Health
  • Risk factors you cannot control:
    • Age
    • Gender
    • Genetics (family history)
    • Ethnicity
maine data
Maine Data
  • 27% report NO physical activity
    • 1 in 5 engage in moderate physical activity ~5 days/week
  • 74% do NOT eat 5 servings of fruits and vegetables daily
  • 25% of Maine adults are obese (2007)
healthy people 2020
Healthy People 2020
  • Americans with a healthful diet:
    • Consume a variety of nutrient-dense foods within and across the food groups, especially:
      • whole grains, fruits, vegetables, low-fat or fat-free milk or milk products, and lean meats and other protein sources.
    • Limit the intake of saturated and trans fats, cholesterol, added sugars, sodium (salt), and alcohol.
healthy people 202061
Healthy People 2020
  • Limit caloric intake to meet caloric needs.
    • All Americans should avoid unhealthy weight gain, and those whose weight is too high may also need to lose weight
food choices
Food Choices
  • Small group exercise
    • What influences your food choices each day?
    • Why do you eat what you eat?
    • Get into groups of ~4 and make a list of what impacts your food choices most days.
      • Turn this list in next time we meet.