1

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

3

Factors Influencing What You Eat

1. Flavor includes:

Taste Smell Appearance

How it feels in the mouth

Texture Temperature

4

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

6

Factors Influencing What You Eat

Demographics Age Gender Educational level Income

7

Factors Influencing What You Eat

Culture and Religion Traditional foods Special

events/celebrations Religious

foods/practices

8

Factors Influencing What You Eat

Health Health status Desire to improve

health/appearance Nutrition knowledge

and attitudes

9

Factors Influencing What You Eat

Social and Emotional Influences Social status Peer pressure Emotional status Food associations

10

Factors Influencing What You Eat

Food Industry and the Media Food industry

Food advertising Food portrayal in

media Reporting of

nutrition/health studies

11

Factors Influencing What You Eat

Environmental Concerns Use of synthetic fertilizers and pesticides Wastefulness of fattening up livestock/poultry

12

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

13

Nutrients are:

Nourishing substances in food that provide energy and promote the growth and maintenance of your body

14

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

15

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)

16

BMR depends on factors such as:

Gender Age Growth Height Temperature Fever and stress Exercise Smoking and caffeine Sleep

17

Classes of Nutrients - Overview

Carbohydrates

Lipids (fats)

Proteins

Vitamins

Minerals

Water

18

Carbohydrates A large class of

nutrients, including: Sugars Starch Fibersthat function as the

body’s primary source of

energy.

19

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

20

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

21

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

22

Water

Inorganic nutrient that plays a vital role in all bodily processes and makes up just over half of the body’s weight

23

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

24

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

25

Carbohydrates 4 kcal/gram

Lipids 9 kcal/gram

Protein 4 kcal/gram

26

More Vocabulary

Micronutrients Macronutrients

Organic nutrients Inorganic nutrients

Connect the columns

Carbohydrates Lipids Proteins Vitamins Minerals Water

27

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

30

Nutrient Density Comparison: % DRI intakes for selected nutrients.

31

Characteristics of A Nutritious Diet

Adequate Balanced Moderate Varied

32

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

33

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

34

Dietary Reference Intakes

RDA and AI – useful in planning diets for individuals

EAR - useful in planning diets for groups

35

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

36

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

42

Food Facts1. Whole foods

2. Organic foods

3. Processed foods

4. Enriched foods

5. Fortified foods

43

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.

44

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

49

Clip art images may not be saved or downloaded and are only to be used for viewing purposes.

Copyright ©2010 John Wiley & Sons, Inc.