Introduction to Human Nutrition

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Introduction to Human Nutrition

• Course Web Page

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Real Hope for Haiti Clinic for Malnourished
Children
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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

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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.

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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

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Nutrition Defined

• Actions in the body include
• Ingestion
• Digestion
• Absorption
• Transport
• Metabolism
• Excretion

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Whats 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

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Classifying Nutrients

• There are 6 Classes of Nutrients
• 1. Carbohydrates
• 2. Lipids (fats)
• 3. Proteins
• 4. Vitamins
• 5. Minerals
• 6. Water

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Body Composition
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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

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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

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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

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Classifying Nutrients

• Nonessential nutrients body can make from other
  nutrients ingested
• ? Examples
• Cholesterol
• Some amino acids

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Classifying Nutrients by Composition

• Organic nutrients - contain carbon
• Carbohydrates
• Lipids
• Proteins
• Vitamins
• Inorganic nutrients - do not contain carbon
• Minerals
• Water

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Quantity Needed

• Macronutrients need in relatively large amounts
• Carbohydrates, lipids, proteins
• Micronutrients need in relatively small amounts
• All other nutrients

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Classifying Nutrients

• Energy-yielding nutrients (3)
• Carbohydrates
• Fats (lipids)
• Proteins
• Where does the energy come from?

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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

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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.

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Energy-Yielding Nutrients
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Energy-Yielding Nutrients

• Carbohydrates C, H, O
• 4 kcal/gram
• Bodys primary source of energy
• Use as glucose
• Glucose is the brains only source of energy
• Carbohydrate stores are limited 12-24 hours (in
  liver and muscle)

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Classes of Carbohydrates

• Simple sugars
• Monosaccharides and disaccharides
• Complex carbohydrates
• Starch
• Fibers
• Carbohydrate rich foods..

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Lipids

• Lipids fats and oils C, H, O
• 9 kcal/gram
• Bodys alternate source of energy
• Use fat along with glucose as an energy source
  most of the time
• Stores are unlimited

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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?

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Proteins

• Proteins C, H, O, N, S
• 4 kcal/gram (same as _______)
• Bodys least desirable source of energy
• WHY? .
• Protein is used for energy only when carbohydrate
  is NOT available as an energy source.
• Protein rich foods?

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Energy-Yielding Non-nutrient

• Alcohol 7 kcal/gram
• Non-nutrient because it interferes with growth,
  maintenance and repair of the body
• Alcohols metabolites are harmful

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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.

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Energy Density
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Evaluating a Food Label

• _____ grams carbohydrate
• _____ grams fat
• _____ grams protein
• TOTAL KCAL ____________

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6 Classes of Nutrients

• Carbohydrates
• Lipids (fats and oils)
• Proteins
• Vitamins
• Minerals
• Water
• Pages 8/9

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Vitamins

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

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Minerals

• Essential
• Inorganic, micronutrient
• Major minerals Ca, P, Na
• Trace minerals Fe, Zn
• Not energy-yielding
• Indestructible

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Water

• Water (H2O)
• Essential
• Organic or inorganic?
• Noncaloric
• We are 60 water

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Not everyone has access to clean water
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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

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Scientific Method

• Observations ? Questions
• Hypotheses ? Predictions
• Test hypotheses/predictions
• Analyze data and draw conclusions
• Share results

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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?

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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?

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Experiments

• Conduct experiments to test the predictions
• Easier said than done when people are involved!
• Well consider research designs later/soon.

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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

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Experimental Design

• Compare the health/lab values of the two groups
  before and after the diet change.
• Example DASH diet study

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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

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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

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The Science of Nutrition

• 1. Epidemiological studies
• Study of populations
• Look for correlations between dietary practices
  and health

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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

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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.

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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

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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.

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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?

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Experimental Studies

• Lab-Based Studies
• Also called in vitro studies
• Examine impact of a substance on living tissue in
  a test tube
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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

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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

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Nutrition and Health

• Chronic health issues associated with diet
  include
• Heart disease
• Hypertension
• Obesity
• Type II Diabetes
• Osteoporosis
• See pages 4/5

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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

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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

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Improving Health

• Risk factors in your control
• Smoking
• Alcohol intake
• Over-consumption of calories
• Physical inactivity
• Poor quality diet

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Improving Health

• Risk factors you cannot control
• Age
• Gender
• Genetics (family history)
• Ethnicity

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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)

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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.

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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

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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.