Introduction to Human Nutrition

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Introduction to Human Nutrition

• Course Web Page

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Chapter Outline

• Nutrition defined
• Classifying nutrients
• Energy
• Nutrition and health
• Evaluating nutritional status
• Levels of nutritional status
• Deficiencies
• Nutritional research
• Nutritional recommendations
• Factors impacting food choices

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Nutrition Defined

• Nutrition the science of foods and the
  nutrients and other substances they contain and
  their actions in the body.

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Nutrition Defined

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

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Nutrition Defined

• Nutrients substances in food that are used in
  the body for
• Energy
• Structural materials
• Regulation of body functions
• Growth, repair and maintenance of tissues
• 40 nutrients identified at this time

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Nutrients

• Multiple ways to classify the nutrients.
• Nutrients can be classified as
• Carbohydrate, protein (6 classes)
• Essential or nonessential
• Organic/inorganic
• Energy yielding

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Classifying Nutrients

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

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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)

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Classifying Nutrients

• Examples of essential nutrients
• Vitamins
• Calcium, iron, and other minerals
• Some of the amino acids

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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

• Organic nutrients - contain carbon
• Carbohydrates, lipids, proteins, vitamins
• Inorganic nutrients - do not contain carbon
• Minerals and water

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Classifying Nutrients

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

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A little more on energy.

• Measure energy in kilocalories in U.S.
• Kcal food calorie Cal
• What most think of as a calorie is really a
  kilocalorie
• 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
• Remember, all energy yielding nutrients are
  caloric.

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Energy in the Body

• Weight is stable when energy in energy out
• Extra energy taken in is stored for later use
• This results in weight gain
• Store the extra energy as
• _____________________
• _____________________
• Inadequate energy intake results in weight loss

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Energy-Yielding Nutrients

• Carbohydrates C, H, O
• 4 kcal/gram
• Bodys primary source of energy
• Use as glucose
• Brains only source of energy
• Stores are limited 12-24 hours (in liver and
  muscle)
• Carbohydrate rich foods..

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Energy-Yielding Nutrients

• Fats C, H, O
• 9 kcal/gram
• Bodys alternate source of energy
• Use fat along with glucose as an energy source
  when ..
• Stores are unlimited

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Energy-Yielding Nutrients

• Proteins C, H, O, N, S
• 4 kcal/gram (same as _______)
• Bodys least desirable source of energy
• WHY? .
• Protein is used for energy when fat when
  carbohydrate stores are empty.

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Energy-Yielding Non-nutrient

• Alcohol C, H, O
• 7 kcal/gram

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Classifying Nutrients

• Non-nutrients substances in foods that do not
  fit into one of the 6 nutrient categories
• Examples
• Fiber
• Alcohol
• Phytochemicals
• Substances in plants that have biological
  activity in the body

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6 Classes of Nutrients

• Carbohydrates
• Lipids (fats)
• Proteins
• Vitamins
• Minerals
• Water

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Vitamins

• Vitamins
• Organic, but not caloric
• Classify as water soluble or water insoluble
• Vitamins serve many functions in the body
• E.g. (you dont need to know these examples yet)
  

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Minerals

• Minerals
• Inorganic, not caloric
• Play many roles in the body
• Some play a structural role
• calcium in bones
• Some are dissolved in body fluids as ions
• Sodium, potassium, calcium. Need proper levels
  for muscle and nerve contraction

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Water

• Water (H2O)
• ??organic or inorganic??
• Noncaloric
• Essential nutrient
• .

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Nutrition Defined

• NO NUTRIENT WORKS ALONE
• Need regular adequate intake of all nutrients for
  optimal functioning.
• Best obtained from food not supplements.
• WHY????

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Nutrition and Health

• Nutrition and health are closely related
• Chronic health issues associated with diet
• Obesity
• Type II Diabetes
• Osteoporosis
• See page 24

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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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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
• 21 engage in moderate physical activity 5
  days/week
• 74 do NOT eat 5 servings of fruits and
  vegetables daily
• 56 are overweight or obese
• 20 are obese
• (2000 data for adults)

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Evaluating Nutritional Status

• (4) Components of evaluating nut. status
• Health and diet history
• Anthropometric data
• Height, weight,
• Physical exam
• Hair, skin, eyes.
• Laboratory tests
• Cholesterol levels, iron levels

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Levels of Nutritional Status

• See handout
• Ideal nutrition .
• Borderline nutrition ..
• Malnourished .
• Who is at greatest risk?
• Over nutrition
• 2 aspects
• Obesity and health

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Nutritional Deficiencies

• Primary vs. secondary deficiency
• Primary inadequate intake of the nutrient
• Secondary body doesnt absorb adequate amounts,
  excretes too much.
• Body mishandles the nutrient

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Nutritional Deficiencies

• Overt vs. covert deficiency
• Overt outward signs of the deficiency
• Covert may be detected by lab tests, but not
  outward signs of the deficiency

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The Science of Nutrition

• Nutritional Research
• Uses scientific method
• Observations
• Questions
• Hypotheses
• Test hypotheses
• Analyze data and draw conclusions
• Share results

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The Science of Nutrition

• Commonly used research designs (page 13)
• Epidemiological study (observe)
• Cross-sectional
• Case-controlled
• Cohort (longitudinal)
• Experimental (intervene)
• Animal studies
• Human clinical trials
• Lab studies

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The Science of Nutrition

• Size matters in research!
• Good studies have large sample sizes
• Preliminary studies have smaller sample sizes

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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
• Study of a population at a given point in time
• Look for correlations between dietary practices
  and health

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Epidemiological Studies

• Case-controlled study
• Compare diet of similar individuals with and
  without a disease/condition
• Look for differences in diet that might account
  for the differences in health

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Epidemiological Studies

• Cohort or 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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Experimental Studies

• Clinical or Human Intervention 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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Clinical Trials

• Terms
• 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
• --------------------------------------------------
  -----------
• See page 14 for strengths and weaknesses of the
  research designs

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Science Of Nutrition

• From scientific studies come nutritional
  recommendations.

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Dietary Recommendations

• Dietary Reference Intakes (DRI)
• EAR - Estimated Average Requirements
• RDA Recommended Dietary Allowances
• AI Adequate Intake
• UL Tolerable Upper Intake Levels
• All based on nutritional research.

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EAR

• Estimated Average Requirements
• Intake amount that appears to meet the needs of
  50 of the population (see graphs on page 17)
• Age, gender, condition based
• Set after review of many research studies

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RDA

• Recommended Dietary Allowances
• RDA is set to meet the needs of 98 of the
  population (without reaching toxic levels)
• Set at a level that is higher than many need
• Why?
• No RDA for energy.why?

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AI

• Adequate Intake (AI)
• AI average amount of the nutrient that a group
  of healthy people consume
• AI is set when there isnt enough research to set
  an estimated average requirement (EAR) or RDA
• Examples Vitamin D, water, fiber

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UL

• Tolerable Upper Intake Level (UL)
• Maximum daily amount of nutrient that appears
  safe for most healthy people
• Intake above the UL is associated with toxicity
  symptoms
• Most often see with overuse of supplements or
  intake of many fortified foods

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Other Recommendations

• Estimated Energy Requirements (EER)
• Caloric intake that will maintain energy balance
  in a healthy person
• Values given are for reference male and female
  who is fairly active
• Values are not very useful for individuals!

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Other Recommendations

• Acceptable Macronutrient Distribution Range
• or, recommended intake of energy yielding
  nutrients
• 45-65 of caloric intake from carbohydrate
• 20-35 of caloric intake from fat
• 10-35 of caloric intake from protein

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Other Recommendations

• Other countries and international organizations
  set their own nutritional recommendations
• e.g. World Health Organization (WHO)

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Food Choices

• Small group exercise
• What influences your food choices each day?

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Food Choices Text Answers

1. Personal preferences
2. Habit
3. Ethnic heritage
4. Tradition
5. Social interactions or pressure
6. Availability
7. Convenience

• Economy
• Positive or negative associations
• Emotional Comfort
• Values -Religious, political, environmental
• Health concerns
• Nutritional value

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