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Chapter 1
Introduction to Nutrition
Learning Objectives
1. Identify factors that influence food selection.2. Define nutrition, kilocalorie, nutrient, and nutrient density3. Identify the classes of nutrients and their characteristics4. Describe four characteristics of a nutritious diet5. Define Dietary Reference Intakes and explain their function6. Compare the EAR, RDA, AI, and UL7. Describe the processes of digestion, absorption, and
metabolism8. Explain how the digestive system works9. Distinguish between whole, processed, and organic foods10. Compare how a meat-based or plant-based diet impact the
environment
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Factors Influencing What You Eat
1. Flavor includes:
Taste Smell Appearance
How it feels in the mouth
Texture Temperature
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The most important consideration when choosing something to eat is flavor.
The most important consideration when choosing something to eat is flavor. (Courtesy of PhotoDisc/Getty Images)
Factors Influencing What You Eat
Other Aspects of Food Cost Convenience Availability Familiarity Nutrition
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Factors Influencing What You Eat
Demographics Age Gender Educational level Income
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Factors Influencing What You Eat
Culture and Religion Traditional foods Special
events/celebrations Religious
foods/practices
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Factors Influencing What You Eat
Health Health status Desire to improve
health/appearance Nutrition knowledge
and attitudes
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Factors Influencing What You Eat
Social and Emotional Influences Social status Peer pressure Emotional status Food associations
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Factors Influencing What You Eat
Food Industry and the Media Food industry
Food advertising Food portrayal in
media Reporting of
nutrition/health studies
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Factors Influencing What You Eat
Environmental Concerns Use of synthetic fertilizers and pesticides Wastefulness of fattening up livestock/poultry
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What is Nutrition?
Nutrition is a science that:studies nutrients and other substances in
foods and in the body and how these nutrients relate to health and disease, and
explores why you choose particular foods and the type of diet you eat
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Nutrients are:
Nourishing substances in food that provide energy and promote the growth and maintenance of your body
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Kilocalories
A measure of the energy in food 1 kilocalorie raises the temperature of 1
kilogram of water 1 degree Celsius Also called a Calorie Abbreviated as kcalorie or kcal When you hear “calorie,” it is really a
kilocalorie
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The number of kilocalories you need is based on: Basal metabolism (about 2/3 of total energy
needs for individuals who are not very active)
Physical activity
Thermic effect or specific dynamic action of foods (5 to 10% of total energy needs)
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BMR depends on factors such as:
Gender Age Growth Height Temperature Fever and stress Exercise Smoking and caffeine Sleep
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Classes of Nutrients - Overview
Carbohydrates
Lipids (fats)
Proteins
Vitamins
Minerals
Water
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Carbohydrates A large class of
nutrients, including: Sugars Starch Fibersthat function as the
body’s primary source of
energy.
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Lipids A group of fatty
substances, including triglycerides and cholesterol, that are not soluble in
water provide a rich source
of energy and structure to cells
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Protein Major structural parts of
the body’s cells that are made of nitrogen-containing amino acids assembled in chains
Particularly rich in animal foods
Present in many plant foods
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Vitamins and Minerals
Vitamins: Noncaloric, organic nutrients found in a wide variety of foods that are essential to:
regulate body processes
maintain the body allow growth and
reproduction
Minerals: Noncaloric, inorganic nutrients found in a wide variety of foods that are essential to: regulate body
processes maintain the body allow growth and
reproduction
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Water
Inorganic nutrient that plays a vital role in all bodily processes and makes up just over half of the body’s weight
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Functions of Nutrients
Nutrients Provide Energy Promote Growth and Maintenance
Regulate Body Processes
Carbohydrates X
Lipids X X X
Proteins X X X
Vitamins X X
Minerals X X
Water X X
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Food Facts
Most foods provide a mix of nutrients
Food contains more than just nutrients – food may contain colorings, flavorings, caffeine, phytochemicals, and other substances
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Carbohydrates 4 kcal/gram
Lipids 9 kcal/gram
Protein 4 kcal/gram
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More Vocabulary
Micronutrients Macronutrients
Organic nutrients Inorganic nutrients
Connect the columns
Carbohydrates Lipids Proteins Vitamins Minerals Water
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Essential Nutrients
Nutrients that either cannot be made in the body or cannot be made in the quantities needed by the body; therefore, we must obtain them through food
EXAMPLES
Glucose, vitamins, minerals, water, some lipids, and some parts of protein
Nutrient Density
Which food is more nutrient dense?
OR
What is nutrient density?
Nutrient density is:
A measure of the nutrients provided in a food
per kcalorie of that food
Empty-Kcalorie foods: provide few nutrients for the number of kcalories they contain
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Nutrient Density Comparison: % DRI intakes for selected nutrients.
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Characteristics of A Nutritious Diet
Adequate Balanced Moderate Varied
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Dietary Reference Intakes (DRI)
Recommended Dietary Allowance (RDA)Intake value sufficient to meet nutrient requirements of 97-98% of all healthy individuals in a group
Estimated Average Requirement (EAR)Intake value estimated to meet requirement of half the healthy individuals in a group
Adequate Intake (AI)
Intake value used when a RDA cannot be based on an EAR because there’s not enough scientific data
Tolerable Upper Intake Level (UL)
Maximum intake level above which toxicity would increase
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Dietary Reference Intakes
Estimated Energy Requirement (EER)The dietary energy intake measured in kcalories that is needed to maintain energy balance in a healthy adult
There is no RDA or Upper Intake Level for kcalories because these concepts do not apply to energy and would lead to weight gain
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Dietary Reference Intakes
RDA and AI – useful in planning diets for individuals
EAR - useful in planning diets for groups
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Digestion, Absorption, & Metabolism
Digestion: Process by which food is broken down into its components in the gastrointestinal tract with the help of digestive enzymes
Absorption: The passage of digested nutrients through the walls of the intestines or stomach into the blood or lymph, where they are transported to the cells
Metabolism: All the chemical processes by which nutrients are used to support life, includes anabolism and catabolism
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Mouth – Oral Cavity
Tongue and teeth help chew food Saliva contains digestive enzymes and
lubricates the food to move further along GI tract
Tongue rolls chewed
food into bolus
From Mouth to Esophagus
When swallowing, the epiglottis covers the tubes to the lungs so that food does not get into the lungs
The bolus moves from
the mouth through the
pharynx to the esophagus What is peristalsis?
Stomach
Food passes from esophagus through the LES into the stomach
Mucous membranes
secrete hydrochloric acid Chyme Pyloric sphincter
Small Intestine
15 – 20 feet long Villi & Microvilli Duodenum – first foot of s.i. – much digestion & absorption goes on Bile – fat digestion Most nutrients pass through villi into blood or lymph vessels – trans- ported to liver - body
Large Intestine
Connects small intestine to the rectum About 5 feet long Receives waste products of digestion and
passes them on to rectum Absorbs water, some minerals, and a few
vitamins (such as vitamin K) made by bacteria residing there
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Food Facts1. Whole foods
2. Organic foods
3. Processed foods
4. Enriched foods
5. Fortified foods
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Organic Foods
Organic food is produced without using most: Conventional pesticides Petroleum-based fertilizers or sewage sludge-
based fertilizers Bioengineering Ionizing radiation (irradiation)
Organic farms must be inspected annually. All organically-raised animals may not be
given hormones or antibiotics, and must have access to pasture.
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Labeling of Organic Foods
Courtesy of USDA
Hot Topic: How the American Diet Impacts the Environment
Consider: Livestock use 30% of the earth’s surface –
increased deforestation has led to the accumulation of greenhouse gases
Livestock farms are major air & water polluters Enormous quantities of water, fuel, fertilizers,
and pesticides are required to grow feed for livestock
Sustainable Agriculture
Produces abundant food without depleting the earth’s resources or polluting its environment
How Restaurants Are Going Green
Energy-efficient equipment and lighting Buying tableware and cups made of recycled
and renewable materials Buying nontoxic cleaning and sanitation
supplies Installing flow restrictors on faucets Recycling Using an energy management program
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