Transcript Chapter One

C HAPTER
1
The Role of Nutrition
in Our Health
PowerPoint® Lecture Slides prepared by
James Bailey, University of Tennessee
Copyright © 2009 Pearson Education, Inc.,
publishing as Pearson Benjamin Cummings.
What Is Nutrition?
Nutrition: is an interdisciplinary and applied study of
food, including
 How food nourishes our bodies
 How food influences our health (mind and body)
Compared with other fields, nutrition is a relatively
new discipline of science.
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Why Is Nutrition Important?
Nutrition contributes to wellness.
Wellness: the absence of disease
 Physical, emotional, and spiritual health
Critical components of wellness
 Nutrition
 Physical activity
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Why Is Nutrition Important?
Nutrition encompasses the following aspects of food
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Consumption
Digestion
Absorption
Metabolism
Storage
Excretion
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Why Is Nutrition Important?
Nutrition also studies these aspects of food
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Psychological
Food safety
Global food supply
Cultural
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Why Is Nutrition Important?
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Figure 1.1
Why Is Nutrition Important?
Nutrition can prevent disease.
 Nutrient deficiency diseases:
 rickets (vitamin D)
 goiter (iodine)
 scurvy (vitamin C)
 Diseases influenced by nutrition:
heart disease; diabetes; high blood pressure;
osteoarthritis, osteoporosis
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Why Is Nutrition Important?
Obesity is a growing problem
across the globe – changes in
obesity that took developing
world nations, such as the US
two to four decades to occur
are taking place in emerging
nations at 2x the pace or
faster!
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Figure 1.2
Promoting Better Nutrition for All
The World Health Organization and member states
began a campaign called: Five Keys to a
Healthy Diet:
1.
2.
3.
4.
5.
Give your baby only breast milk for the first six months of life;
Eat a variety of foods;
Eat plenty of fruits and vegetables;
Eat moderate amounts of fat and oils;
Eat less salt and sugars.
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What Are Nutrients?
Nutrients: the chemicals in foods that are critical to
human growth and function.
carbohydrates
vitamins
fats and oils
minerals
proteins
water
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What Are Nutrients?
Macronutrients: nutrients required in relatively large
amounts (g or Kg).
 Provide energy
 Carbohydrates; fats and oils; proteins
Micronutrients: nutrients required in smaller
amounts (g or mg).
 Vitamins and minerals
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Energy from Nutrients
We measure energy in kilocalories (kcal) or
kiloJoules (kJ).
On food labels in America, the term “calorie”
appears. It should actually state: kilocalories.
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Carbohydrates
 Primary source of fuel for the body, especially for
the brain
 Provide 4 kcal (or 17 kJ) per gram
 Carbohydrates are found in grains (wheat, rice),
vegetables, fruits, and legumes
 Sugars are also carbohydrate
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Fats and Oils
 Are composed of lipids, molecules that are
insoluble in water
 Provide 9 kcal (38 kJ) per gram
 Are an important energy source during rest or low
intensity exercise
 Are found in butter and vegetable oils
 Are source of fat-soluble vitamins and essential
fatty acids
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Proteins
 Are chains of amino acids
 Can supply 4 kcal (17 kJ) of energy per gram, but
are not a primary energy source
 Are an important source of nitrogen
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Proteins
Proteins are important for
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Building cells and tissues
Maintaining bones
Repairing damage
Regulating metabolism
Fluid balance
Protein sources include meats, fish, dairy products,
seeds, nuts, and legumes.
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Vitamins
Vitamins: organic molecules that assist in regulating
body processes. [Organic means that the molecule contains carbon atoms.]
Vitamins are micronutrients needed to support the
body. They do not yeild energy, so they have no kcal
or kJ in them. There are two categories:
1. Fat-soluble vitamins
2. Water-soluble vitamins
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Vitamins
Fat-soluble vitamins
 Vitamins A, D, E, and K
 Dissolve easily in fats and oils
Fat-soluble vitamins can be stored in the body.
Toxicity can occur, especially from vitamin A.
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Vitamins
Water-soluble vitamins
 Vitamin C and the B vitamins
 Remain dissolved in water
Excess water-soluble vitamins are eliminated by the
kidneys daily and cannot be stored in our bodies.
This is why we must eat more of these vitamins each
and every day.
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Minerals
Minerals: inorganic substances required for body
processes. They are atoms, not molecules.
Minerals include, for example:
sodium, calcium, iron, potassium, and magnesium.
Minerals have many different functions such as fluid
regulation, bone structure, muscle movement, and
nerve functioning.
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Minerals
Our bodies require at least 100 mg/day of the major
minerals such as calcium, phosphorus, magnesium,
sodium, potassium, and chloride.
We require less than 100 mg/day of the trace
minerals such as iron, zinc, copper, iodine, and
fluoride.
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Water
Water is a critical nutrient for health and survival.
Water is involved in many body processes.
fluid balance
nutrient transport
nerve impulses
removal of wastes
muscle contractions
chemical reactions
many, many more…
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Determining Nutrient Needs
Dietary Reference Intakes (DRIs): updated
nutritional standards.
 Expand on the traditional RDA values
 Set standards for nutrients that do not have RDA
values
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Determining Nutrient Needs
DRIs identify the
 Amount of a nutrient needed to prevent deficiency
disease in healthy people
 Amount of a nutrient which may reduce the risk of
chronic disease
 Upper level of safety for nutrients
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Determining Nutrient Needs
Figure 1.8
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Determining Nutrient Needs
DRIs consist of four values
1.
2.
3.
4.
Estimated Average Requirement (EAR)
Recommended Dietary Allowances (RDA)
Adequate Intake (AI)
Tolerable Upper-Intake Level (UL)
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Determining Nutrient Needs
Estimated Average Requirement (EAR)
 The average daily intake level of a nutrient that will
meet the needs of half of the people in a particular
category
 Are used to determine the Recommended Dietary
Allowance (RDA) of a nutrient
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Determining Nutrient Needs: EAR
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Figure 1.9
Determining Nutrient Needs
Recommended Dietary Allowances (RDA)
 The average daily intake level required to meet the
needs of 97 to 98% of people in a given life stage
and gender
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Determining Nutrient Needs: RDA
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Figure 1.10
Determining Nutrient Needs
Adequate Intake (AI)
 Recommended average daily intake level for a
nutrient
 Based on observations and estimates from
experiments
 Used when the RDA is not yet established: calcium,
vitamin D, vitamin K, fluoride
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Determining Nutrient Needs
Tolerable Upper Intake Level (UL)
 Highest average daily intake level that is not likely
to have adverse effects on the health of most people
 Consumption of a nutrient at levels above the UL is
not considered safe
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Determining Nutrient Needs
Estimated Energy Requirement (EER)
 Average dietary energy intake (kcal) to maintain
energy balance
 Based on age, gender, weight, height, and level of
physical activity
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Determining Nutrient Needs
Acceptable Macronutrient Distribution Ranges
(AMDR)
 The portion of the energy intake that should come
from each macronutrient
 The range of energy intake from carbohydrate, fat,
and protein associated with reduced risk of chronic
disease
 The range of macronutrient intake that provides
adequate levels of essential nutrients
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Determining Nutrient Needs: AMDR
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Table 1.4
Nutrition Research
The scientific method
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Observation: describe the phenomenon
Create a hypothesis
Design, collect, and analyze the data
Interpret the data
Generalize the findings, develop a theory
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Research Models
 Epidemiological studies
 Human experiments
 Case control studies
 Clinical studies
 Animal studies
Note: Each type of study has advantages and
disadvantages.
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Research Study Factors
 Controls
 Does not receive treatment
 Sample size
 Appropriate to measure a difference between
treatment groups
 Placebo
 Similar appearance and taste
 Double-blind
 Neither subjects nor researchers know who is in the
placebo or treatment groups
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Evaluating Media Reports
Ask these questions to determine the scientific
validity
 Who is reporting the information?
 Who conducted the research and who paid for it?
 Is the report based on reputable research studies?
 Was there a control and an experimental group?
 Was the sample size large enough to rule out
chance variation?
 Was a placebo effectively administered?
 Was the experiment double blind?
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