Chapter Two Key Concepts in Nutrition
Chapter Learning Objectives
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Define calorie, nutrient density, and empty-calorie food and explain why people should
decrease consumption of empty-calorie food.
Identify the six basic types of nutrients found in food and describe their characteristics.
Describe the major functions of carbohydrates, proteins, lipids, vitamins, minerals, and
water in the body.
Explain the effect of alcohol consumption on the body.
Explain how the senses affect a person’s intake of food.
Identify the structures of the digestive system and describe digestion, absorption, transport,
and utilization of nutrients from food.
Describe the body mass index and explain why it is important to achieve and maintain a
healthy weight.
Chapter Summary
1. Define calorie, nutrient density, and empty-calorie food and explain why
people should decrease consumption of empty-calorie food.
The amount of energy that a person derives from food is measured in units
called calories. A calorie is the amount of energy needed to heat one kilogram
of water (about 2.2 pounds) by approximately two degrees Fahrenheit
(one degree Celsius). Nutrient density refers to the number of nutrients
per calorie of a food. For the most part, if you eat nutrient-dense food, you
receive more nutrition in a smaller number of total calories. An emptycalorie
food is one that contains higher proportions of calories but few if
any nutrients. Empty-calorie food usually contains high amounts of sugar
and fat. Often one or two servings of empty-calorie food per day can add the
extra three hundred to four hundred calories that cause weight gain in the
general population. Therefore, it would be wise for most people to decrease
consumption of these foods.
2. Identify the six basic types of nutrients found in food and describe their
characteristics.
The six essential nutrients are carbohydrates, proteins, lipids, vitamins, minerals,
and water. Carbohydrates include starch, sugar, and dietary fiber. Carbohydrates
provide the body with four calories of energy per gram. Proteins are
large, complex molecules that contain long chains of amino acids. Lipids can be
triglycerides, cholesterol, or phospholipids. Lipids provide abundant energy, as
each gram contains nine calories. Vitamins are organic compounds, while minerals
are inorganic elements. Both are needed in relatively small amounts by the
body for regulation of metabolic processes. Water is the most important nutrient.
It is a universal solvent and a critical component of metabolic processes.
3. Describe the major functions of carbohydrates, proteins, lipids, vitamins,
minerals, and water in the body.
The primary role of carbohydrates in the diet is to supply energy. The primary
function of protein is to provide amino acids, which the body uses to build
and repair muscles and other tissues. In addition, the body uses protein to
form enzymes, hormones, and antibodies. Lipids provide energy at a rate of
nine calories per gram of food eaten.
Vitamins and minerals are needed in relatively small amounts by the body for
regulation of metabolic processes. Water is essential to all forms of life. It is
a perfect medium for the metabolic processes of the body. In addition, water
aids in temperature regulation, waste removal, and hydration.
4. Explain the effect of alcohol consumption on the body.
Alcohol has mixed effects on the body. Some studies have indicated that
alcohol, when consumed in moderation, can reduce the risk of cardiovascular
events and decrease the occurrence of diabetes and dementia. However, an excessive
amount of alcohol in the diet is associated with cancers of the digestive
system as well as cirrhosis, a fatal liver disease
.
5. Explain how the senses affect a person’s intake of food.
There are five recognized primary tastes: sweet, salty, bitter, sour, and umami.
In addition, when we see a very attractively presented dish, we anticipate its
taste. Smell and taste sensations work together to provide most of the flavor.
People also describe the consistency or feel of food in the mouth as important.
The sizzling of steaks or the accompanying sound of a flaming dish as it is
served can also add to the excitement and pleasure of eating.
6. Identify the structures of the digestive system and describe digestion,
absorption, transport, and utilization of nutrients from food.
The structures of the digestive system include the oral cavity, the pharynx, the
esophagus, the stomach, the small intestine, the large intestine, the rectum, the
anus, the liver, the gallbladder, and the pancreas.
The digestive process includes both the physical movement of food down the
digestive tract and the secretion of enzymes and fluids. The teeth chew the
food, the salivary glands secrete saliva, and the stomach holds and mixes the
food. The small intestine is responsible for most digestive and absorptive roles.
The major role of the large intestine is to reabsorb water, minerals, and bile
salts. The rectum stores the waste, and the anus allows for elimination. The liver
produces bile, the gallbladder stores it, and the pancreas adds bicarbonate and
enzymes to the chyme in the small intestine for the final phase of digestion.
When digestion is completed, starches and sugars have been broken down into
monosaccharides, and lipids have been disassembled into glycerol, fatty acids,
and monoglycerides. The long-chain fats enter the lymphatic system. The
monosaccharide and short-chain fatty acids are sent to the liver for use in metabolism.
Proteins are broken down into amino acids and then absorbed, and
the amino acids travel through the blood to the liver to be used by the body.
7. Describe the body mass index and explain why it is important to achieve and
maintain a healthy weight.
The body mass index (BMI) is a numerical calculation that reflects the relationship
between a person’s height and weight. This calculation can indicate
if the person’s weight is in a healthy range. Statistically, individuals who have
high BMI values are at increased risk of what are generally referred to as the
chronic diseases. These diseases include obesity, type 2 diabetes, arthritis, cardiovascular
disease (including high blood pressure, or hypertension), stroke,
and coronary heart disease.
Application Exercise Solutions
Exercise 1
Match the organ on the left with its function on the right.
Components of the
Digestive System
J__Mouth, teeth, tongue
and salivary glands
F__Pharynx
K__Esophagus
H__Stomach
A__Small intestine
Function
A. Mixes chyme with bile and pancreatic juices to ensure
complete digestion; products of digestion are absorbed here.
B. Muscular sphincter that releases waste
C. Performs metabolic regulation and produces bile
D. Stores and concentrates bile
E. Secretes enzymes and bicarbonate to digest starches,
proteins, and fats
F. Common passage for swallowing food
G. Reabsorbs water and bile; compacts waste
H. receives the bolus and mixes it into a liquid; adds acids
and enzymes to digest proteins
I. Stores wastes until they can be eliminated
J. Grinds food into smaller pieces and mixes it with saliva
K. Transports the bolus to the stomach
G__Large intestine
I__Rectum
B__Anus
C__Liver
D__Gallbladder
E__Pancreas
Exercise 2
Food items can be classified generally by the energy yielding nutrients they contain. Some food items
have empty calories, while others are nutrient dense. See how well you can distinguish them. Indicate
with a check mark the major nutrient contributions of each of these food items. Also indicate whether
each is high or low in nutrient density. (All the food items listed in the table
contain vitamins and minerals in varying levels.)
Food
Carbohydrate
Protein
Bacon
Lipid
High or low
X
LOW
Baked Beans
X
HIGH
Cookies
X
LOW
Corn
X
HIGH
Cream Cheese
X
Eggs
Grapefruit juice
X
X
LOW
HIGH
HIGH
Grapes
X
HIGH
Green beans
X
HIGH
Ham
X
HIGH
Jelly beans
X
LOW
Nonfat milk
X
HIGH
Pasta
X
HIGH
Rice cereal
X
HIGH
Salmon
X
HIGH
Sirloin Steak
X
HIGH
Sour cream
X
Tofu
Waffles
X
X
LOW
HIGH
HIGH
Key Terms
amino acid, p. 19
calorie, p. 18
digestive tract, p. 26
energy balance, p. 30
fatty acid, p. 20
high-density lipoprotein
lipid, p. 20
metabolism, p. 28
obesity, p. 29
protein, p. 19
basal metabolism, p. 18
carbohydrate, p. 18
empty-calorie
enzyme, p. 26
fiber, p. 19
(HDL), p. 21
low-density lipoprotein
mineral, p. 21
overweight, p. 29
vitamin, p. 21
body mass index (BMI),p. 29
digestion, p. 25
food, p. 22
essential nutrient, p. 18
glucose, p. 28
kilocalorie, p. 18
(LDL), p. 21
nutrient density, p. 22
phytochemical, p. 21
benefits, p. 104
Chapter’s Concepts and Teaching Tips
The key concepts identified in this chapter are:
1. Digestive system and it components. Student must be able to name the major components
of the digestive system in the correct order from ingestion of food to elimination of
waste.
Teaching tips related to this chapter include:
1. Student should be asked to label a diagram of the major components of digestion and the
general location of digestive activity.
2. The 4 major or macronutrients should be identified for
a. Caloric amounts per gram
b. Calories percentages on the plate as provided in the text.
c. Major digestive point in the body where the macronutrient is absorbed and the
nutrients most basic components are absorbed
3. Student should be asked to draw, on a paper dinner plate, what they had for a given full
meal. Then have the students redraw the meal separating protein, fat and carbohydrates
into the four sections of the plate in estimated proportion of what they ate.
Case Study Answers
John is a manager at a family restaurant in a busy suburban location. Recently
he heard that the wait staff was having trouble meeting the requests of some of
the families who were steady customers. John wants to approach the owners
about adding some healthier items to the menu, but he has decided to gather
some data to support the need for this change before opening the discussion.
1. Why do you think John sees a need for healthier menu items in the
market described above?
Customers have requested certain items and or requested alterations of ingredients by other.
2. What can John do to obtain the data he needs to support these
suggestions? Internet research and a survey of what the competition offers.
3. What obstacles do you think John might encounter as he works on his
plan? Some items that are very popular with current customers might be unalterable in their current
form. Added menu items should have unique identifiers and descriptions on the menu.
Review Your Learning Answer Key
Note: Answers to Review Your Learning are identified in red.
Select the best answer for each question.
1. Oils and fats are part of a class of nutrients called
A. amino acids.
B. proteins.
C. starches.
D. lipids.
2. Carbohydrate and protein food items yield how
many calories per gram?
A. 2
B. 4
C. 6
D. 8
3. Proteins are complex compounds formed by long
chains of
A. starch.
B. cholesterol.
C. amino acids.
D. phospholipids.
4. Studies have suggested that moderate consumption
of alcohol has
A. some beneficial effects on health.
B. some detrimental effects on health.
C. no known effects on health.
D. mixed effects on health.
5. The three energy-yielding nutrients are
A. proteins, vitamins, and lipids.
B. proteins, carbohydrates, and minerals.
C. carbohydrates, lipids, and vitamins.
D. carbohydrates, proteins, and lipids.
6. What is the most important nutrient to the body?
A. Carbohydrates
B. Proteins
C. Lipids
D. Water
7. Which carbohydrate found in food is NOT digested
by the human body?
A. Fiber
B. Sugar
C. Starch
D. Maltose
8. Cookies, candies, and sweetened beverages are considered
what type of food?
A. Nutrient-dense
B. Empty-calorie
C. Healthy
D. Fast
9. Sugars are absorbed in the
A. small intestine.
B. large intestine.
C. stomach.
D. liver.
10. Bile is produced in the liver and stored in the
A. pancreas.
B. gallbladder.
C. large intestine.
D. small intestine.
Suggested In-Class Activities
1. See Paper plates exercise under the instructor c teaching tips
2. Student can separate into teams. The instructor can then assign a major nutrient to each
team. Team members then prepare an argument as to which nutrient is most important in
the body. The instructor or another student can be the final “judge” as to which team has
proposed the best argument.
Suggested Homework Activities
Students can keep a log of what they ate over the weekend. Have their food choice been
affected by what they have learned? Can they estimate their caloric intake based upon
the calories per gram given in the text? Will they use an on line source for this
information?