Download Unit Three: The Science Of Nutrition

Food Studies 30
Unit Three
The Science Of Nutrition
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Unit 3
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Unit 3
Unit Three: The Science Of Nutrition
The following concept web illustrates the major topics presented in this unit.
Proteins
Fats
Water
Carbohydrates
Vitamins and
Minerals
Essential
Nutrients
The Science of Nutrition
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Unit 3
Unit Overview
Unit Two introduced you to the concept of nutrients and Canada’s Food Guide To
Healthy Eating. In that unit you learned how Canada’s Food Guide can help you to
choose nutrients that promote good health. This concern for nutrients and how the
body uses them is the basis for the study of nutrition.
Unit Three will introduce you to the science of nutrition. The study of nutritional
sciences is extensive. This unit cannot provide an in-depth study of the science;
rather, it will discuss basic information about nutrients, their functions, and sources.
You will also be referred to several reliable Internet sites for more explanations.
Information in this Unit will build on Unit Two by discussing fats, cholesterol, and
fibre in more detail.
This Unit does not contain activities within the course content. Instead, your
assignment will consist of fifty multiple choice questions. All questions are found at
the end of this Unit in the assignment section.
The following are suggested web-based resources to help you add information to
the course material, and to help complete the multiple choice questions that are the
assessment for this Unit. You may use other reliable print and on-line resources to
supplement the information provided.
Tip Sheets from the Dietitians of Canada (topics include
Vitamins and Minerals for Athletes ;
Eating Well for Vegetarian Athletes ; Vitamin D: What you need to know ; Do I Need A Vitamin Or Mineral
Supplement? ; and Fuel to burn, energy to spare: new value in carbohydrates and fibre are just a few of the
topics you can find at the website below.
http://www.dietitians.ca/public/content/eat_well_live_well/english/faqs_tips_facts/fact_sheets/index.asp
Saskatchewan Ministry of Health has several fact sheets on nutrition on their
website at: http://www.health.gov.sk.ca/nutrition-exercise
Check out Calcium for your Bones, Cholesterol and your Health, Healthy Foods for my School, and
others that interest you.
Beef Information Centre (http://www.beefinfo.org/default.aspx) has information on topics
such as the following:
Iron: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=92&SecID=3
Protein: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=111&SecID=3
B Vitamins: http://www.beefinfo.org/Default.aspx?ID=13&ArticleID=93&SecID=3
Heart and Stroke Foundation Health Check™ http://www.healthcheck.org/en/nutritionalinformation/nutritional-information.html
Heart and Stroke Foundation
http://www.heartandstroke.com/site/c.ikIQLcMWJtE/b.3483951/k.8CDD/Healthy_Eating.htm
Nutrient Value of Some Common Foods http://www.hc-sc.gc.ca/fn-an/nutrition/fiche-nutridata/nutrient_value-valeurs_nutritives-eng.php
R.O.V.E.R.
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Essential Nutrients
In the science of nutrition, the nutrient forms the base. As a reminder, nutrients
are the chemicals that allow our bodies to build and renew themselves. Nutrients are
divided into six categories. You were introduced to the following six categories of
nutrients in Unit Two.

carbohydrates

fats

proteins

water

vitamins

minerals
These six nutrients are called essential nutrients. They must be provided by food
because the body does not produce them in sufficient quantities or cannot make
them at all.
The body depends upon the six nutrients for different purposes and it requires
different amounts of each depending on age, gender, and health. Throughout Unit
Three you will learn about each of the essential nutrients in more detail. As you
work through the information you will also notice that there is discussion about how
some nutrients depend on one another for proper functioning.
Three of the six essential nutrients provide calories or energy. They are
carbohydrates, fats, and proteins. Most foods are a combination of these three
nutrients. For this reason, they are sometimes referred to as macronutrients.
One gram of pure fat supplies 9 calories
One gram of pure carbohydrate supplies 4 calories
One gram of pure protein supplies 4 calories
Vitamins and minerals are essential nutrients that provide no calories. They must be
provided through the diet because the body cannot manufacture them in quantities
adequate to ensure good health. These essential nutrients are needed in smaller
amounts than the other nutrients; therefore, they are often referred to as
micronutrients.
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Are You Getting All The Nutrients You Need?
Scientists have established how much of certain
nutrients people need. In Canada, Canada’s Food
Guide To Healthy Eating provides direction in
selecting a nutritionally balanced diet. There are
also some specific sources of information available
to judge a person’s dietary needs, including the
Recommended Nutrient Intakes (RNI), sometimes
called Reference Daily Intake (RDI), and the
Recommended Dietary Allowances (RDA).
Each of the above can be found in scientifically
based charts that are guidelines for the amounts of many nutrients needed daily.
The RNIs or RDIs are Canadian, while the RDA is an American reference. Canadians
are encouraged to follow the recommendations of the RNI/RDI. The Canadian
system is currently undergoing change. The RNIs are being replaced by the Dietary
Reference Intakes (DRI). In time, you can expect to see more reference to this
alternate system.
Either way, know that the charts provide specific recommendations for determining
the required amount of each nutrient.
Combining the recommendations of the RNI/RDIs or the new DRIs, and Canada’s
Food Guide To Healthy Eating can help you to be sure your diet is nutritious.
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Carbohydrates
Carbohydrates are the most common nutrient. All foods of plant origin contain
carbohydrates. These include fruit, vegetables, breads, and cereals. Milk is the only
food of animal origin that contains carbohydrates (CHO). More than 50% of the total
calories you consume should come from carbohydrates – but choose wisely.
The three types of carbohydrates are sugars, starch, and fibre.
Simple carbohydrates are sometimes called simple sugars. Glucose is the most
important simple sugar. Through the process of digestion, all food breaks down to
this simple sugar. Glucose is used for energy and for repair of body tissues.
Carbohydrates can also be classified as complex. These carbohydrates consist of
three or more simple sugars. Complex carbohydrates are low in fat and rich in
vitamins, minerals, starch, and proteins. Rich sources of complex carbohydrates
include grains such as wheat, corn, and oats, and foods made from them. Many
Canadians eat too much sugar or simple carbohydrates, and not enough starch and
fibre (complex carbohydrates).
Some people believe that carbohydrate foods are fattening. This is a myth. Any food
eaten in excess of energy needs can contribute to weight gain. Focus on enjoying
carbohydrate foods in moderation, watch what is added to these foods, and balance
your intake with active living.
Eating carbohydrates does not cause diabetes like some people believe. Diabetes is
a complex disease with many different causes. Type 2 diabetes (non-insulin
dependent) is, however, influenced by a lifestyle that is sedentary and lacks a
healthy diet. Different racial and ethnic groups in developed countries are also at a
higher risk for diabetes. People of Aboriginal descent are three to five times more
likely than the general population to have or develop diabetes. People of LatinAmerican, African, Asian, and Hispanic descent living in North America also have a
higher incidence of diabetes. One of the best ways to prevent Type 2 diabetes is to
eat well, enjoy regular physical activity, and maintain a healthy weight.
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Fibre
Complex carbohydrates have the added value of providing dietary fibre. Dietary
fibres are the parts of food that are not broken down in the intestinal tract. Because
the body cannot digest dietary fibre, it passes through the digestive tract almost
unchanged. For this reason, no calories are derived from it.
You may be wondering why you need dietary fibre. Dietary fibre has several
important roles.

It provides bulk to maintain good bowel health and regularity.

It helps to lower blood cholesterol levels.

It helps to regulate blood sugar levels.
Fibre is classified as soluble or insoluble.
Fibre Type
Soluble Dietary Fibre
Insoluble Dietary Fibre
Description
A soft fibre that forms gels which
absorb water. It helps in controlling
blood sugar and in lowering blood
cholesterol.
Once called roughage, this type of fibre
holds water and helps to prevent and
control bowel problems.
Best Sources
Oat products, pulses, and pectin-rich
fruit (apples, strawberries, and citrus
fruit)
Wheat bran and wheat bran cereals,
whole grain foods (whole wheat or rye
bread, brown rice), fruit and vegetables
(including skin)
There is no official Canadian Recommended Daily Intake for fibre at this time. Adults
should try to eat 20 to 35 grams of fibre throughout each day. Children older than
two years should be given fibre equal to their age plus five grams per day.
Food varies in the amount of fibre that it contains. The following chart outlines some
low to high sources of dietary fibre in four different food groups.
Fibre Content Of Foods
There are many resources that can tell you the amount of fibre in certain foods.
Check out your favourite foods. Are they high, medium or low sources of fibre?
http://www.dialadietitian.org/nutritionsubcat.asp?id=31
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Fats
Fats are essential for good health. They are found in
both animal and plant foods, although fruits and
vegetables contain very little fat. In addition to being a
major source of energy, fats are also a source of
essential fatty acids. Essential fatty acids (EFA)
cannot be made by the body but are needed for normal
growth and metabolism.
Fat is a natural part of some food or it can be added in
meal preparation. For healthy eating you need to focus on specific types of fat.
Different types of fat affect your health in different ways. Some types of fat raise
your blood cholesterol level, which increases your risk of developing heart disease.
Read about fats in some of the selected web-sites in Unit Three to learn more about
the functions of fat, where fat is found, the different types of fat, and ways to
control your fat intake.
Proteins
Proteins are found in both animal and
plant foods. Proteins are necessary for
manufacturing, maintaining, and
repairing body tissues. As well, they
help to regulate body processes such
as the balance of water, acids and
bases, and the movement of nutrients in and out of cells. Proteins contribute to the
immune system by producing antibodies.
Unit Four of this course will look at proteins in more depth.
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Water
The human body is approximately 70% water. The percentage of water in the body
depends on the amount of body fat a person has. People with high percentages of
body fat have lower percentages of body water than normal.
Much of this water is found inside your cells. The remaining water is found in the
spaces surrounding cells, and in your bloodstream.
Water has many functions.
Functions Of Water In The Body

keeps your skin soft and elastic, and
lubricates your joints

helps chemical reactions occur

carries nutrients and waste products
throughout the body

helps to regulate body temperature

protects your body by acting as a
shock absorber
Although the principal sources of water are beverages, many foods contain large
amounts of water. Some foods such as tomatoes, oranges, watermelon, and lettuce
are over 80% water. You need to consume at least six to eight cups of water per
day. This replaces the water lost in urine, sweat, and breathing. If you are very
active or are in a hot climate, you will need to take in more water. Coffee, tea, soft
drinks, alcohol, and other beverages that contain caffeine cannot help your need for
water. These liquids are known as diuretics. Diuretics cause you to lose water.
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Vitamins And Minerals
As you have learned, carbohydrates, fats, and proteins are the only nutrients that
directly provide energy. However, they are not the only nutrients you need. Vitamins
and minerals are just as important even though they do not provide calories.
The body requires tiny amounts of vitamins and minerals. All the vitamins and
minerals you need in a day combined weigh less than a dime. The amounts of
vitamins and minerals you need may be small, but they are vital dietary substances.
They are used in many of the body’s chemical reactions. Both help keep body
processes working normally and are needed for growth and repair of the body.
Minerals can also become part of body tissues.
Vitamins
Virtually all foods contain some vitamins. When vitamins were first discovered, they
were given letter names (example: vitamin A, B, and so on). As scientists were able
to analyze the chemical makeup of the vitamins, they gave vitamins chemical names
such as riboflavin for vitamin B2. Today, many vitamins are still commonly referred
to by their letter names.
Types Of Vitamins
Presently, there are thirteen vitamins. You will become familiar with these as you
read information from the suggested web-sites and your own choices of reliable
nutrition information. You should also be aware of two other types.

The human body is capable of converting some substances into vitamins. These
vitamins are known as provitamins. Beta-carotene is an example. It is used by
the body to make vitamin A.

Antioxidants are substances that keep oxygen-free molecules in the blood from
combining with “bad” cholesterol. The antioxidant vitamins are C, E, and betacarotene.
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Meeting Your Vitamin Needs
It is best to obtain the needed vitamins from foods rather than from supplements.
Some vitamins can be found in a wide range of foods, while others are limited to
just a few. Many factors contribute to a particular food’s vitamin concentration.

an animal’s feed

the manner by which the produce is harvested, stored, or processed

the type of soil, sunlight, rainfall, and temperature in the food’s growing
atmosphere
You can control vitamin concentration through careful food preparation. The
following are some hints for getting the vitamins you need.

Be aware that different cooking methods influence the amount of vitamins
retained. For instance, cooking in water causes vitamins to be washed out. This
makes steaming, microwaving, roasting, and grilling better alternatives to boiling,
stewing, and braising.

Storage affects vitamin concentrations. For instance, prolonged exposure to air
may destroy vitamin C, and riboflavin is sensitive to sunlight. For this reason,
milk products are stored in opaque containers.
Continue to read information on vitamins. Make notes of the different vitamins and
their purposes and the sources of those vitamins. Use the chart that follows for your
notes. This will help you answer the multiple-choice questions as the end of the
lesson.
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Main Points To Remember
Name Of Vitamin
Vitamin
Rich Food
Deficiency
(letter and/or chemical)
Functions
Sources
Diseases
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Minerals
Unlike vitamins that are produced and found in living materials, minerals are not
produced and cannot be manufactured by the human body. They need to be
obtained by eating plants that have drawn minerals from the ground or the flesh of
animals that have eaten such plants.
Most minerals become a part of the body, such as teeth and bones. Others are used
to make substances that the body needs.
Meeting Your Mineral Needs
The amount of minerals you need to consume each day measures out to about 15
ml or a tablespoon. You need greater amounts of minerals than vitamins. Even
though some minerals are needed in very tiny amounts, getting the right amount is
important to health. Most minerals have a narrow safe range. You will see in the
video you will watch that minerals are divided into different groups. You require
varying amounts of each group.
It is not difficult to get the right balance of minerals when you eat of wide variety of
healthy foods. Certain groups of people may, however, need to be concerned about
the amount of calcium, iron, and folacin they consume.
A calcium calculator is provided on the Osteoporosis Canada website and is a quick
and easy tool to measure your calcium intake for a day and to let you know how
close you are to meeting your daily calcium needs. Give it a try.
http://www.osteoporosis.ca/index.php/ci_id/5355/la_id/1.htm
The several web-sites given and those print and on-line resources you find will help
you learn more about the roles minerals play in our diets. Use the following chart to
record information as you find it. Be sure to include calcium, iron, folacin, sodium
and at least two other minerals in the chart. Pay particular attention to the function
of the minerals, as well as quantities required, methods of preserving the minerals,
and food sources.
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Main Points To Remember
Name Of Mineral
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Mineral
Rich Food
Deficiency
Functions
Sources
Diseases
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Unit 3
How Vitamins And Minerals Work Together
On their own, vitamins and minerals have specific functions. In addition, some
nutrients depend on one another for proper functioning. The following list outlines
some examples of how vitamins and minerals work together.
Nutrient Combination
Result
Iron + vitamin C
Increases iron absorption
Calcium + vitamin D
Increases calcium absorption
Calcium + phosphorous
Increases calcium absorption
Copper + vitamin C or zinc
Interferes with copper absorption
Fortification And Enrichment
Many foods in their raw form are packed with nutrients. However, some of these
foods must be processed before consumers can use them. Grains and cereals are an
example.
Sometimes the entire kernel of grain is used. This creates a whole grain product.
These products contain most of the kernel’s original nutrients. Removal of the
kernel’s bran and germ, along with the fibre and nutrients they contain is common.
The remaining endosperm is made into products such as white flour or breakfast
cereals.
The three main parts of the grain kernel are the bran, endosperm and germ.
BRAN: outer covering consisting mainly of noncaloric cellulose fibre, B
vitamins and protein
ENDOSPERM: contains three quarters of the protein of the kernel and the B
vitamins
GERM: contains vegetable oil, vitamin E and some B vitamins
Usually, some of the nutrients lost in processing are added to the product so the
total is close to the original levels. The process is known as enrichment. In the
case of grains and cereals, these foods are enriched with riboflavin, niacin, thiamin,
and iron.
Foods may also be fortified with vitamins or minerals. A fortified food is one in
which nutrients not normally found in the food are added to make it more nutritious.
Milk is an example. It is fortified with vitamin D to enhance calcium absorption.
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Unit Summary
The concept web presented at the start of the unit will remind you about the
important topics discussed in Unit Three.
After you have completed the assignment, and you leave this unit, look back on
some of the major topics that you have learned about. Think as well about how you
could apply your learning in your daily life.
Proteins
Fats
Water
Carbohydrates
Vitamins and
Minerals
Essential
Nutrients
The Science of Nutrition
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Unit 3
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Unit 3