Download uncorrected page proofs

Chapter 5
O
PR
O
PA
G
E
As health status has improved over time and life
expectancy has increased, behavioural factors have
had more time to affect the health of individuals. One
significant behavioural determinant that affects health is
nutrition. Poor nutrition is linked to a number of health
conditions including cardiovascular disease, diabetes
mellitus, colorectal cancer, obesity and osteoporosis. These
conditions contribute to a large number of premature
deaths and significant levels of morbidity in Australia.
Having an understanding of the role of key nutrients in the
protection or development of these conditions is essential
to enable a range of interventions to be developed and
further improvements in health to be made.
FS
Nutrition and
the NHPAs
EC
TE
D
KEY KNOWLEDGE
1.6The role of nutrition in addressing the following conditions
recognised in the NHPAs: cardiovascular disease, diabetes mellitus,
colorectal cancer, obesity and osteoporosis, taking into account,
where relevant, the function (as a determinant of health) and major
food sources of protein, carbohydrate (including fibre), fats (mono,
poly, saturated and trans), water, calcium, phosphorus, sodium and
vitamin D (pages 00–00)
U
N
C
O
R
R
KEY SKILL
• Explain the role of nutrition in addressing specific conditions within
the NHPAs, including the functions and major food sources of
relevant nutrients (pages 00, 00, 00, 00).
212 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 212
11 June 2015 7:57 PM
KEY TERM DEFINITIONS
U
N
C
O
R
R
EC
TE
D
PA
G
E
PR
O
O
FS
bile a chemical released into the intestines to assist in
the absorption of dietary fat
bone matrix the structure of bone that allows
calcium and phosphorus to be deposited, therefore
making the tissue hard. The bone matrix consists
mainly of collagen
digestive tract a collection of organs that carry out
digestion. The organs are the mouth, oesophagus,
stomach, small intestine, large intestine, rectum and
anus
energy-dense foods foods that contain significant
amounts of fat, therefore contributing large amounts
of energy to the diet
fortified (foods) foods that have particular nutrients
added to them during processing
heart failure a condition characterised by the heart’s
inability to supply sufficient blood flow to body cells
and tissues
indigestible cannot be absorbed by the body
intracellular fluid fluid between the cells
legume a type of pod. Examples include alfalfa, peas,
beans, lentils and peanuts
macronutrients nutrients that are required in large
amounts, such as protein, carbohydrates and fats
metabolism refers to all of the chemical processes
occurring in the body. Metabolism includes the
processes that take place to break food down into its
most basic components and the processes that turn
these components into energy or body cells
micronutrients nutrients that are required in small
amounts, such as vitamins and minerals
nutrient a substance that is used by living things
to build tissue or provide energy in order to assist in
growth or to keep the organism alive
ossification the process whereby bones are hardened
by laying down the minerals calcium and phosphorus
peak bone mass the highest level of bone mass
reached throughout the life span (usually attained in
the late 20s or early 30s)
protective nutrient any nutrient that acts to protect
a person from a certain condition
risk nutrient any nutrient that increases the chances
of developing a certain condition
c05NutritionAndTheNHPAs.indd 213
11 June 2015 7:57 PM
5.1
The nutrients and the NHPAs: Carbohydrates
(including fibre) and protein
KEY CONCEPT Understanding the role that nutrients play in
addressing health conditions identified within the NHPAs: carbohydrates
(including fibre) and protein
FS
Nutrition is one of the key behavioural determinants of health in Australia. It
can act to decrease or increase the risk of a range of conditions identified within
the NHPAs, including cardiovascular health, diabetes mellitus, colorectal cancer,
obesity and osteoporosis. With issues such as increasing rates of obesity and type 2
diabetes in Australia, it is important to examine the nutrients found in food to
gain an understanding of how nutrition can be used to improve health status and
address the conditions within the NHPAs.
Having a balanced food intake with plenty of variety is the key to maintaining
an adequate diet and therefore reducing the risk of diet-related conditions. Six
categories of nutrients are needed for optimal health. They are:
• carbohydrates (including fibre)
• protein
• fats
• vitamins
• minerals
• water.
Carbohydrates, protein and fats are collectively termed macronutrients, and
vitamins and minerals are known as micronutrients. Water is not technically a
nutrient, so it is not classified in either group. However, large quantities of water
are required for optimal health.
There are many different nutrients required by the body for good health. The
main nutrients that play a risk or protective role in relation to the NHPAs are
summarised in figure 5.1. Each nutrient plays a different role and is required in
different amounts, but all are important for good health.
Unit 3
O
AOS 1
See more
Carbohydrate
Topic 8
All
nutrients
R
R
EC
TE
D
PA
G
E
PR
O
Concept 2
O
Carbohydrates
(including
fibre)
Fats
Minerals
Vitamins
Water
U
N
C
Protein
Monounsaturated
Polyunsaturated
Saturated
Trans
Vitamin
D
Calcium
Phosphorus
Sodium
FIgURE 5.1 Numerous nutrients can increase or decrease the risk of conditions identified within the NHPAs.
Carbohydrates
Carbohydrates are considered a macronutrient as we tend to need relatively large
quantities each day. The main function of carbohydrates is to provide fuel for energy.
When food is eaten, the body metabolises the carbohydrates in the food into useful
glucose molecules, the most basic form of carbohydrate. Glucose molecules are
214
UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd
214
11 June 2015 7:57 PM
O
FS
then used for energy production. In terms of energy production,
one gram of carbohydrate produces 16 kilojoules of energy.
Glucose molecules (and therefore carbohydrates) not used
by the body for energy are stored as adipose (or fat) tissue.
This process can be reversed if glucose is needed by the body.
For example, in times of starvation, fatty tissue can be broken
down and converted back into glucose to be used for energy.
If continually eaten in excess, carbohydrates can contribute to
obesity and related conditions such as cardiovascular disease,
diabetes mellitus (particularly type 2 and gestational) and
colorectal cancer.
PR
O
Sources of carbohydrates
Figure 5.2 Carbohydrates are used
as a fuel for energy production. If not
used for energy, excess carbohydrates
are stored as fat, which can contribute
to weight gain.
EC
TE
D
PA
G
E
Carbohydrates are found in foods of plant origin. Different
foods contain varying amounts of carbohydrates and therefore
varying amounts of energy. Care should be taken to ensure that
the foods selected do not contain unnecessarily high levels of
energy. For example, foods containing high levels of sugar, such as soft drinks, are
rich in carbohydrates, but they often contain more energy than is required by the
individual and usually contain low levels of other nutrients.
Major food sources of carbohydrates include:
• fruits such as oranges, grapes and bananas
• starchy vegetables such as potatoes and parsnips
• corn
• beans
• pasta
• bread
• rice
• breakfast cereals such as wheat biscuits and bran.
Fibre
U
N
C
O
R
R
The main function of fibre is to regulate the functioning
of the digestive system. Adequate fibre intake prevents
constipation by adding bulk to faeces and assists in removing
waste products through the digestive tract.
Technically a type of carbohydrate, fibre is made up of the
indigestible parts of plant matter found in cereals, vegetables
and fruits. Foods that are high in fibre, particularly fruit and
vegetables, are usually rich in vitamins and minerals and low
in fat, which can improve health and reduce the risk of a
number of NHPA conditions, including:
• colorectal cancer. Although the relationship between fibre
intake and the development of colorectal cancer is still
unclear, societies that eat high-fibre diets have much lower
rates of colorectal cancer
• obesity. By providing a feeling of fullness without the
kilojoules, a food intake high in fibre can reduce the
amount of energy consumed from other foods
• diabetes mellitus (type 2 and gestational). Fibre has been
shown to reduce the absorption of glucose from the
small intestine. This can decrease the risk of obesity and
associated conditions such as diabetes mellitus
Figure 5.3 Fibre is essential for the
health of the digestive system and can
decrease the risk of colorectal cancer.
Nutrition and the NHPAs • CHAPTER 5 215
c05NutritionAndTheNHPAs.indd 215
11 June 2015 7:57 PM
5.1 The nutrients and the NHPAs: Carbohydrates (including fibre) and protein
FS
• cardiovascular disease. Fibre reduces blood cholesterol levels by binding to bile.
Bile is released into the stomach to assist in the digestion of dietary fat. Once the
fat is digested, bile is normally reabsorbed into the blood stream. Fibre binds
with bile and excretes it, preventing it from being reabsorbed. The liver makes
more bile to replace what has been excreted. Cholesterol is a key component of
bile, so bile production reduces the amount of cholesterol in the blood. Foods
high in fibre generally have lower saturated fat content, which further reduces
the production of cholesterol.
Sources of fibre
PR
O
O
The Australian Heart Foundation recommends that adults eat between 25 and
30 grams of fibre every day. Children should consume 10 grams plus one gram for
every year of age (for example, 20 grams for a ten-year-old).
Examples of foods that contain fibre are:
• bran flake cereal
• wholemeal bread
• fruit and vegetables — particularly good sources include raspberries, apples,
bananas, pears, oranges, peas, potatoes, broccoli and corn
• baked beans.
Fibre absorbs water, so if the amount of fibre in the diet is increased, water
consumption should also be increased.
Protein
PA
G
E
Figure 5.4 Bran, which is found
in many breakfast cereals, is a good
source of fibre. Unfortunately, too
few people get enough of this
nutrient.
O
R
R
EC
TE
D
Protein is considered a macronutrient. The primary function of protein is to
promote the growth, maintenance and repair of body cells. However, as a secondary
function, protein is also used as a fuel for energy production. This means that if
there are insufficient carbohydrates and fat for energy use, protein may be used.
Protein that has been converted into muscle and other tissues can also be used as
a fuel source during times of starvation. Protein yields approximately 17 kilojoules
per gram when used for energy.
Although protein deficiency is rare in Australia, a World Health Organization
report (2003) suggests that protein deficiency may contribute to decreased bone
density and an increased risk of osteoporosis.
According to the Australian Institute of Sport (2014), excess protein may be
converted into glucose and then stored as fat if not used for growth, repair or energy.
As a result, excess protein intake can contribute to obesity and related NHPA
conditions such as cardiovascular disease, diabetes mellitus (specifically type 2 and
gestational diabetes) and colorectal cancer.
Although most people in Australia
have enough protein in their diet, some
people supplement their dietary protein
with products such as protein shakes in
an attempt to build muscle. According to
the Better Health Channel, people taking
supplementary protein while weight
training add no more muscle than those
not taking protein supplements. Excess
protein intake can put strain on the kidneys
and liver, which are responsible for protein
metabolism. Excess protein may also lead to
excessive loss of the mineral calcium from
bones, which can contribute to osteoporosis.
U
N
C
Figure 5.5 Nuts, grains, lean meat,
fish and eggs are rich sources of
protein.
216 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 216
11 June 2015 7:57 PM
Sources of protein
Unit 3
AOS 1
Topic 8
See more
Protein
O
FS
Concept 1
Unit 3
AOS 1
Topic 8
Concept 1
Do more
Protein
R
EC
TE
D
PA
G
E
PR
O
Although found in vast amounts in animal products, protein can also be found in
many foods of plant origin. Some rich sources of protein include:
• animal origin:
–– eggs
–– milk, cheese and other dairy products (except cream)
–– beef
–– chicken and other poultry
–– fish and seafood.
• plant origin:
–– soy products (such as tofu and soya milk)
–– legumes
–– nuts
–– whole grain cereals
–– brown rice.
Care should also be taken when choosing protein-rich foods, as some options
are healthier than others. For example, steak is a good source of protein, but if it
is not a lean cut (that is, if it has a lot of fat around and through it), the benefits
of getting the protein from the meat may be outweighed by the extra fat that is
being consumed. Much of the fat from red meat is saturated fat, which has further
negative health implications. Fish, such as salmon, is a better option as it is rich
in protein but has half the fat of a normal steak, and only a small percentage is
saturated fat. Lentils are another good source of protein, with very low levels of fat
and high levels of fibre.
R
TEST your knowledge
U
N
C
O
1 What are the six categories of nutrients?
2 Explain what is meant by the term:
(a)macronutrient
(b)micronutrient
(c)metabolism.
3 (a) What is the main function of carbohydrates?
(b) How much energy does one gram of
carbohydrate produce?
4 (a) What is the function of fibre?
(b) List five foods that are major sources of fibre.
5 (a) Outline the functions of protein.
(b) How much energy does one gram of protein
provide?
(c) List four food sources of protein.
APPLY your knowledge
6 Explain the possible positive or negative
health impacts of consuming a diet high
in the following nutrients over a period of
time.
(a)Carbohydrates
(b)Fibre
(c)Protein
7 Outline the possible health impacts of consuming
diets low in the following nutrients over a period
of time.
(a)Fibre
(b)Protein
8 Identify and explain any relationships that exist
between obesity, cardiovascular disease, diabetes
mellitus, colorectal cancer, osteoporosis and:
(a) carbohydrates (including fibre)
(b)protein.
9 Approximately how much fibre should the following
people consume each day?
(a) Fletcher, a 7-year-old male
(b) Laura, a 15-year-old female
(c) Lisa, a 22-year-old female
Nutrition and the NHPAs • CHAPTER 5 217
c05NutritionAndTheNHPAs.indd 217
11 June 2015 7:57 PM
5.2
The nutrients and the NHPAs: Fats and water
KEY CONCEPT Understanding the role that nutrients play in addressing
health conditions identified within the NHPAs: fats and water
Fats
FS
Fats (also known as lipids) are a macronutrient. The main function of fats is as fuel
for energy. Fats are a rich source of energy, providing 37 kilojoules per gram. This
explains why foods high in fat but low in other valuable nutrients are referred to
as energy-dense foods.
Fats are an important part of a balanced diet, but some types of fats are better
for health than others. Most people get enough fats in their diet. In fact, Australians
are more likely to overconsume than underconsume this nutrient, particularly the
type known as saturated fats.
As all fats contribute 37 kilojoules per gram, if they are eaten in excess they
contribute to weight gain and obesity and associated effects, such as increased risk
of cardiovascular disease, diabetes mellitus (type 2) and colorectal cancer.
Fats are classified according to their chemical make-up and are categorised into
four broad types (see figure 5.6). Regardless of the type of fat, they all contribute
the same number of kilojoules of energy per gram to the body.
PR
O
O
eLesson:
Omega 3
Searchlight ID: eles-0221
E
Unit 3
AOS 1
Concept 3
PA
G
See more
Fat
Topic 8
TE
D
All fats
Polyunsaturated
Saturated
Trans fats
Omega 3
O
R
R
EC
Monounsaturated
U
N
C
Omega 6
Unit 3
AOS 1
Do more
Fat
Topic 8
Concept 3
218
FIgURE 5.6 The different types of fat
Monounsaturated fats
Monounsaturated fats are considered one of the more healthy types of fat, though
their energy contribution is still 37 kilojoules per gram. Monounsaturated fats
can assist in the lowering of low density lipoproteins (LDL, the ‘bad’ cholesterol).
(See page 47 in Chapter 2 for more information on cholesterol.) The exact
mechanism of this process is not fully understood, but replacing saturated fats
with monounsaturated fats decreases the level of LDL cholesterol, reducing the
risk of atherosclerosis and cardiovascular disease. Monounsaturated fats have also
been shown to decrease the impact of impaired glucose regulation and decrease the
risk of type 2 diabetes when consumed in place of saturated fat. In moderation,
UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd
218
11 June 2015 7:57 PM
therefore, monounsaturated fats can have positive health effects. Like any fat,
however, too much will still contribute to weight gain, obesity and associated
conditions.
O
PR
O
Monounsaturated fats are liquid at room temperature and begin to solidify when
placed in the refrigerator.
Foods rich in monounsaturated fats include:
• olive oil
• avocado
• canola oil
• nuts
• peanut butter.
FS
Food sources of monounsaturated fat
Polyunsaturated fats
O
R
R
EC
TE
D
PA
G
E
Polyunsaturated fats are also considered one of the more healthy types of fat,
although they contribute the same kilojoule value as other types. The greatest
gains are achieved when saturated and trans fats are replaced with monounsaturated
and polyunsaturated fats. There are two main categories of polyunsaturated fats:
omega 3 and omega 6. Both omega 3 and omega 6 fats act to lower LDL cholesterol
in the blood stream and increase HDL cholesterol, therefore reducing the risk of
heart disease. Polyunsaturated fats also have other functions:
• Omega 3 polyunsaturated fats appear to promote the elasticity of blood vessels,
which can reduce blood pressure and the risk of cardiovascular disease.
• Omega 3 polyunsaturated fats also prevent blood clots in the arteries. Blood
clots can block blood flow in blood vessels and are one of the causes of heart
attack and stroke.
• According to the American Heart Foundation (2009), omega 6 polyunsaturated
fats decrease the impact of impaired glucose regulation and ultimately decrease
the risk of developing type 2 diabetes.
• Polyunsaturated fat reduce the impact of inflammation of blood vessels and can
reduce the risk of cardiovascular disease as a result.
These two types of fat need to be eaten in appropriate
ratios to achieve their full benefit. Adults should be eating
omega 3 and omega 6 fats in a ratio of about 1 : 4. Very few
people are deficient in these types of fats, but most people
tend to eat too much omega 6 fat.
C
Food sources of polyunsaturated fats
U
N
Polyunsaturated fats are generally liquid at room temperature
and when refrigerated.
Food sources for omega 3 fats include:
• fish (particularly oily fish such as mackerel, trout,
sardines, tuna and salmon)
• soy and canola oils, and canola-based margarine.
Food sources for omega 6 fats include:
• most nuts and seeds
• corn, safflower and soy oils.
Saturated fats
When overconsumed, saturated fats are often associated with negative effects on
health. Saturated fat has been shown to increase LDL cholesterol production in
Figure 5.7 Oily fish such as
mackerel are a good source of
omega 3.
Nutrition and the NHPAs • CHAPTER 5 219
c05NutritionAndTheNHPAs.indd 219
11 June 2015 7:57 PM
5.2 The nutrients and the NHPAs: Fats and water
the liver and also contains substantial amounts of LDL cholesterol, which can
contribute to atherosclerosis and cardiovascular disease.
Diets high in saturated fat have been shown to increase the impact of impaired
glucose regulation and the risk of type 2 diabetes.
Although saturated fat can increase the risk of obesity, which is a risk factor for
colorectal cancer, excessive saturated fat intake also appears to increase the risk of
colorectal cancer directly (that is, even in people who are not obese).
FS
Food sources of saturated fat
PA
G
Trans fats
E
PR
O
O
Saturated fats are mostly found in foods of animal origin and are usually solid at
room temperature.
Examples include:
• fatty cuts of meat. Saturated fat can be seen along the edges and through some
meats.
• full cream milk, cream and cheese
• coconut milk and cream
• most fried takeaway food
• most commercially baked goods such as pastries and biscuits.
Trans fats behave much like saturated fats in the body by raising LDL cholesterol
levels. Trans fats also work to decrease levels of HDL cholesterol, thereby increasing
the risk of cardiovascular disease.
Trans fats can also interfere with the structure of cell membranes, which can
affect the movement of nutrients and fluids in and out of the cells. If glucose is
restricted from entering the cells, insulin levels increase in response to the higher
blood glucose levels. This can contribute to insulin resistance and increases the risk
of type 2 diabetes.
TE
D
FIgURE 5.8 The visible fat on meat is
largely saturated fat.
Energy input
Energy output
O
R
R
Lose weight =
EC
In order to lose weight, energy intake must be less than energy output:
U
N
C
If a person wants to gain weight, energy intake must be more than
energy output:
Gain weight =
Energy output
Energy input
To maintain weight, energy input and energy output must be equal:
Maintain weight =
Energy input
Energy output
FIgURE 5.9 The effects of different energy inputs and outputs
220
Food sources of trans fats
Although small amounts of trans fats are found
naturally in certain foods, including beef,
mutton and dairy products, most trans fats
are created when liquid oil is converted into
solid fat by a process called hydrogenation.
For this reason, trans fats are generally found
in processed foods, such as pies, pastries and
cakes. Margarines and solid spreads made for
cooking are sometimes high in trans fats and
should make up only a small part of the diet.
The nutrition information found on packaging
of processed foods usually indicates how much
trans fat the food contains. By consulting these
labels, consumers can choose foods with little or
no trans fats.
The relationship between
food and body weight
In order to lose, gain or maintain body weight,
the balance between energy intake (energy
consumed) and energy output (energy expended)
is important.
UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd
220
11 June 2015 7:57 PM
Carbohydrates, protein and fat (energy intakes) that are not used for energy
production can be stored as adipose tissue (fat), so someone who continually takes
in more energy than they use risks becoming overweight and/or obese. Obesity is
a risk factor for many other conditions, such as type 2 diabetes, colorectal cancer
and cardiovascular disease, and can reduce an individual’s overall level of health.
E
O
PR
O
Although it has no nutritional value, water is vital for human survival. Water
makes up between 55 and 75 per cent of our body mass. Water is needed for many
functions within the body. The amount of water required daily ranges from about
1.2 to 3 litres.
As water contains no nutrients and therefore no energy, it can assist with weight
management when consumed instead of other fluids. Regular consumption of
water can reduce the risk of obesity and related conditions such as cardiovascular
disease and diabetes.
Water is also absorbed by fibre and therefore plays a role in digestive health and
the prevention of colorectal cancer.
FS
Water
PA
G
Sources of water
Unit 3
AOS 1
Topic 8
See more
Water
Concept 4
R
R
EC
TE
D
Most people’s daily intake of water does not come from drinking water at all. In
fact, all food and drink contains water, and this is where most people get a majority
of their supply Water in its purest form is the best source, as many other fluids
contain additional kilojoules (as a result of added sugars and other additives) and
no other valuable nutrients.
Major sources of water include:
• water in its pure form
• other drinks that contain water, such as cordials, soft drinks, tea and coffee
• fruits, including apples, watermelon, oranges, grapefruit and tomatoes
• vegetables such as celery, broccoli, lettuce, carrots and cucumber.
O
TEST your knowledge
U
N
C
1 (a) What are the main functions of fats in the body?
(b) How much energy does one gram of fat
provide?
2 (a) What are the four types of fat?
(b) List four food sources for each type of fat.
(c) Which two fats are considered the ‘bad’ fats?
Why?
3 Outline the health benefits of polyunsaturated fat.
4 What are trans fats?
APPLY your knowledge
5 Per gram, which nutrient contributes the most
energy: carbohydrate, protein or fat?
6 Outline the similarities and differences between:
(a) monounsaturated and polyunsaturated fats
(b) saturated and trans fats.
7 Why would it be a good idea to replace most drinks
with pure water?
8 Even though we should replace saturated
and trans fats with monounsaturated and
polyunsaturated fats, why is it important to not
increase overall fat intake?
9 Explain how fats can address cardiovascular disease.
10 Identify and explain any relationships that exist
between obesity, cardiovascular disease, diabetes
mellitus, colorectal cancer, osteoporosis and:
(a) monounsaturated fat
(b) polyunsaturated fat
(c) saturated fat
(d) trans fat
(e)water.
Nutrition and the NHPAs • CHAPTER 5 221
c05NutritionAndTheNHPAs.indd 221
11 June 2015 7:57 PM
5.3
he nutrients and the NHPAs: Calcium,
T
phosphorus, sodium and vitamin D
KEY CONCEPT Understanding the role that nutrients play in
addressing health conditions identified within the NHPAs: calcium,
phosphorus, sodium and vitamin D
FS
Calcium
R
O
C
U
N
Calcium
phosphate
Males
Females
Peak bone
mass
Menopause
EC
Bone mass
TE
D
PA
G
E
PR
O
O
Calcium is the most abundant mineral in the body. Most of the calcium in our
bodies (about 99 per cent) is stored in the bones, with the other 1 per cent in the
blood, muscles and intracellular fluid. Perhaps the most important role of calcium is
as a hardening or ossifying agent for hard tissue such as teeth, bones and cartilage.
Calcium is capable of moving in and out of the bones and will move out of the bones
if there are insufficient amounts available in the blood for other body functions.
If an individual does not get enough calcium throughout their life, they are less
likely to achieve their optimal peak bone mass. The more bone mass that is built
up in the early years (particularly during youth), the greater the chance the person
has of maintaining good bone health throughout life. If optimal peak bone mass is
not achieved, the individual is at greater risk of developing the NHPA condition of
osteoporosis and suffering from fractures later in life (see figure 5.10).
Bone
matrix
Figure 5.11 The ossification
process
Gradual loss
of bone mass
in old age
Puberty; bone
size increases
R
The growth of hard tissue
starts with the laying down
of the bone matrix, which is
like a framework for the bone
structure. The bone matrix is
largely made up of collagen,
which consists of protein and
vitamin C and provides ‘storage
holes’ for calcium phosphate.
Once the matrix is in place,
crystals of calcium phosphate fill
the holes, which makes the tissue
strong and hard. This process
is known as ossification.
Ossification is much like dipping
a sponge into a bucket of plaster.
The once‑soft sponge maintains
its shape but becomes very hard
as the plaster dries. The matrix is
like the sponge and the calcium
phosphate is like the plaster. They
are both needed for adequate
bone formation.
Once bones have stopped
growing, ossification continues
to replace old crystals with new
ones. As people age, this process
becomes less efficient and more
crystals need replacing than the
body can produce. This leads to
weaker bones after the age of
about thirty (see figure 5.11).
0
20
40
Age (years)
60
80
Figure 5.10 Bone mass over the life span for males and females
Source: Medical Research Council, www.mrc-hnr.cam.ac.uk/research/bone-health/pbm.html.
Food sources of calcium
Good sources of calcium are dairy products such as milk, cheese and yoghurt.
Other sources include:
• sardines and salmon (with bones)
• green leafy vegetables, such as broccoli and spinach
• fortified soy milk
• tofu made with calcium sulphate
• fortified orange juice.
Phosphorus
Phosphorus has a number of roles in the body. Its main function is to work with
calcium to harden or ossify bones and teeth. Calcium and phosphorus bind to
222 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 222
11 June 2015 7:57 PM
form calcium phosphate, which is the ossifying agent for hard tissue. As a result,
adequate intake of phosphorus is important to decrease the risk of developing
osteoporosis.
Australians tend to get sufficient phosphorus in their diet, but certain conditions,
such as diabetes and alcoholism, can prevent it from being absorbed, leaving
the individual with low levels of phosphate. This can cause loss of bone density,
weakness and poor appetite.
O
PR
O
As phosphorus is an important part of all living things, it is found in most foods.
Foods that are rich in protein are particularly rich in phosphorus and include:
• dairy products such as milk, cheese and yoghurt
• meat such as chicken and beef
• eggs
• fish
• nuts
• legumes.
FS
Food sources of phosphorus
PA
G
E
Sodium
Figure 5.12 Calcium and
phosphorus are required to maintain
the health of bones.
O
R
R
EC
TE
D
Sodium is an important mineral for human life. It plays a role in the regulation
of fluids in the body, including water and blood. Fluid is drawn to sodium, so
the amount of sodium in the blood influences the amount of fluid that stays in
the cells. Through this mechanism, sodium regulates the balance between fluid
in the cells (intracellular fluid) and the fluid outside the cells (extracellular fluid).
Most Australians get more than enough sodium in their diet. According to the
Better Health Channel, the average Australian consumes eight to nine times the
amount of sodium they need for good health. High levels of sodium in the body
can draw excess fluid out of the cells. This increases blood volume and contributes
to hypertension. Other effects linked to excessive sodium intake include:
• heart failure. Increased blood volume and hypertension force the heart to work
harder. Heart failure can result if the heart cannot keep up with demand from
the body
• stroke and heart attack. Hypertension associated with excess sodium intake
contributes to higher rates of stroke and heart attack
• osteoporosis. Excess sodium causes calcium to be excreted in urine, which can
lead to the demineralisation of bones and the NHPA condition osteoporosis.
C
Food sources of sodium
U
N
Foods containing sodium include:
• table salt
• olives
• fish
• meat (especially pork)
• cheese
• many processed foods, such as tomato sauce, packet soups and sauces, canned
vegetables, pizza, pies and ready meals.
Vitamin D
Figure 5.13 Excess sodium increases
blood volume and contributes to
hypertension.
Vitamin D is required for the absorption of calcium and phosphorus from
the intestine into the blood stream. Due to the essential role that calcium and
phosphorus play in the formation of hard tissue such as bones and teeth, a lack of
Nutrition and the NHPAs • CHAPTER 5 223
c05NutritionAndTheNHPAs.indd 223
11 June 2015 7:57 PM
5.3 The nutrients and the NHPAs: Calcium, phosphorus, sodium and vitamin D
See more
Calcium
See more
Phosphorous
Topic 8
Concept 5
Food sources of vitamin D
O
Unit 3
AOS 1
FS
vitamin D leads to weakened bones and teeth. Osteoporosis (weak, frail bones) is a
common musculoskeletal conditions caused by a lack of vitamin D.
Most Australians get their vitamin D requirement from exposure to ultraviolet
(UV) rays (from sunlight). UV rays are converted to vitamin D in the skin. Vitamin D
deficiency was not a major concern in the past, as most Australians were exposed
to enough UV rays to synthesise adequate amounts of Vitamin D. However, as
more and more people heed the sun safety message, the amount of exposure to UV
rays has decreased, and vitamin D deficiency is becoming more common. This is
particularly the case in elderly people, as they are more likely to spend extended
periods indoors.
PA
G
E
PR
O
Vitamin D does not occur naturally in many foods. Fish (particularly tuna, salmon,
mackerel, sardines and herring) is the best source of vitamin D. Small amounts can
also be found in:
• beef liver
• cheese
• egg yolks.
Some brands of milk, breakfast cereals and orange juice are fortified with
vitamin D, but it is important to check the packaging.
TEST your knowledge
APPLY your knowledge
5 Describe the symptoms that might be present for
someone who was not getting enough:
(a)calcium
(b) vitamin D.
6 Why is a deficiency in calcium during the younger
years not likely to affect health until later life?
7 Use the Calcium calculator links in the
Resources section of your eBookPLUS to
find the weblink and questions for this activity.
8 (a) Why do most Australians get enough vitamin D?
(b) Which groups of people might be at risk of
vitamin D deficiency? Explain why.
9 Explain how excessive sodium intake can
contribute to:
(a) cardiovascular disease
(b)osteoporosis.
U
N
C
O
R
R
EC
TE
D
1 (a)Using figure 5.11, describe the pattern of bone
mass over the life span.
(b) Which life span stages are the most important
for building bone density?
(c) Explain the role that calcium, phosphorus and
vitamin D play in the prevention of osteoporosis.
2 (a) What is the bone matrix?
(b) What is the bone matrix made from?
(c) What is ossification?
3 Explain the possible impacts on health from
consuming a diet high in sodium.
4 List three food sources for:
(a)calcium
(b)phosphorus
(c)sodium
(d) vitamin D.
224 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 224
11 June 2015 7:57 PM
5.4
The role of nutrients in addressing the NHPAs
Risk nutrients
Table 5.1 Risk nutrients
Risk nutrients
Saturated and trans fats
R
Cardiovascular health
O
PR
O
E
Function
Contains LDL cholesterol, which is a risk factor for atherosclerosis and therefore
cardiovascular disease.
Stimulates the liver to produce LDL cholesterol, which further increases atherosclerosis and
cardiovascular disease.
Can lead to weight gain, obesity and associated conditions, including cardiovascular disease.
Sodium
Can increase blood volume and contribute to hypertension as a result. Hypertension increases
the risk of heart attack and stroke.
O
R
Carbohydrates, protein
and fats
Carbohydrates, protein
and fats
Can lead to weight gain and obesity, increasing the risk of diabetes mellitus.
Trans fats
Can interfere with cell membranes and contribute to high blood glucose levels. This can
contribute to impaired glucose regulation and diabetes mellitus.
Saturated fat
Can reduce the ability of the body to effectively use insulin, contributing to increased risk of
impaired glucose regulation.
Carbohydrates, protein
and fats
Can lead to weight gain and obesity, increasing the risk of colorectal cancer.
Saturated fat
Appears to increase the risk of colorectal cancer.
Obesity
Carbohydrates, protein
and fats
Can lead to weight gain and obesity if not used for energy.
Osteoporosis
Protein
Excess protein intake can increase the loss of calcium from bones, which increases the risk of
osteoporosis.
Sodium
Excess sodium causes calcium to be excreted in urine, which can decrease bone density and
contribute to osteoporosis.
Protein deficiency may reduce bone density and increase the risk of osteoporosis.
U
N
C
Diabetes mellitus
Figure 5.14 Fruit and vegetables
are packed with protective nutrients
and have small amounts (if any) of the
risk nutrients.
EC
Condition
TE
D
Many nutrients can contribute to ill health if they
are overconsumed. These nutrients and the related
conditions are summarised in table 5.1.
PA
G
As we have seen, there is a strong relationship
between nutrients and conditions included in the
NHPAs. Nutrients that tend to put people at risk of
certain diseases are known as risk nutrients. Those
that protect people from diet-related diseases
are known as protective nutrients. This section
summarises the risk and protective nutrients related
to health conditions in several NHPAs, including
cardiovascular health, diabetes mellitus, colorectal
cancer, obesity and osteoporosis.
FS
KEY CONCEPT Understanding the role of nutrition in addressing
conditions recognised in the NHPAs: cardiovascular disease, diabetes
mellitus, colorectal cancer, obesity and osteoporosis, including the
function and major food sources of protein, carbohydrates (including
fibre), fats (mono, poly, saturated and trans), water, calcium,
phosphorus, sodium and vitamin D.
Colorectal cancer
Nutrition and the NHPAs • CHAPTER 5 225
c05NutritionAndTheNHPAs.indd 225
11 June 2015 7:57 PM
5.4 The role of nutrients in addressing the NHPAs
Protective nutrients
Protective nutrients are those that play a role in promoting health. Individuals
without a balanced food intake are at increased risk of being deficient in these
nutrients. Some nutrients that play a protective role in some of the National Health
Priority Areas are summarised in table 5.2.
Table 5.2 Protective nutrients
Obesity
Increases feelings of fullness, which can reduce overeating, obesity and risk of cardiovascular disease.
Reduces blood cholesterol levels, which reduces the rate of atherosclerosis and cardiovascular disease.
Reduces LDL cholesterol, which reduces the rate of atherosclerosis and cardiovascular disease.
Polyunsaturated fats
Reduces LDL cholesterol, which reduces the risk of atherosclerosis and cardiovascular disease.
Omega 3 increases elasticity of blood vessels and prevents blood clots, reducing the risk of heart
attack and stroke.
Increases HDL cholesterol, which decreases blood cholesterol levels.
Water
Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated
conditions, including cardiovascular disease.
Fibre
Increases the feeling of fullness, which can reduce overeating, preventing obesity and reducing risk of
diabetes mellitus.
Reduces blood glucose levels, which can protect against obesity impaired glucose regulation and
diabetes mellitus.
Polyunsaturated fats
May decrease the impact of impaired glucose regulation and reduce the risk of diabetes mellitus.
Water
Contributes no kilojoules to energy intake, reducing the risk of obesity and associated conditions,
including diabetes mellitus.
Fibre
Fibre assists in moving digested food matter through the digestive tract and absorbs water, which
adds bulk to faeces, making them easier to pass. The exact relationship between fibre and colorectal
cancer is unknown but fibre appears to decrease the risk of colorectal cancer.
Water
Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated
conditions, including colorectal cancer.
Is absorbed by fibre and assists in flushing waste, which may decrease the risk of colorectal cancer.
Fibre
Provides a feeling of fullness without the kilojoules. This can reduce the amount of energy consumed
from other foods, therefore preventing weight gain and obesity.
Reduces energy intake by decreasing the absorption of glucose into the blood stream. This can mean
glucose is not transformed into adipose (fat) tissue.
E
PR
O
Water
Contributes no kilojoules to energy intake, so can reduce the risk of obesity and associated
conditions, including cardiovascular disease.
Calcium
Acts as a hardening agent for the mineralisation of bones, which increases bone mass and reduces
the risk of osteoporosis.
R
Osteoporosis
O
Monounsaturated fats
PA
G
Colorectal
cancer
Fibre
TE
D
Diabetes
mellitus
Function
EC
Cardiovascular
health
Protective nutrients
FS
Condition
Works with calcium as a hardening agent for bones, which increases bone mass and reduces the risk
of osteoporosis.
Required for the absorption of calcium and phosphorus from the intestine into the blood stream,
which increases bone density and decreases the risk of osteoporosis.
U
N
C
O
Vitamin D
R
Phosphorus
TEST your knowledge
1 What is meant by the terms ‘risk nutrients’ and
‘protective nutrients’?
2 Describe the role of nutrition in addressing the
following NHPAs.
(a) Cardiovascular health
(b) Diabetes mellitus
(c) Colorectal cancer
(d)Obesity
(e)Osteoporosis
3 What is the difference between saturated fat and
poly-/monounsaturated fats with regard to their
effect on cholesterol?
4 (a) What is cholesterol?
(b) Why is too much LDL cholesterol a risk to the
health of individuals?
(c) Which NHPA are high cholesterol levels
associated with?
APPLY your knowledge
5 Provide two suggestions that could help someone
reduce their levels of LDL (bad) cholesterol in their
body.
6 Why is balance the key when it comes to risk and
protective nutrients? Why wouldn’t you cut out risk
nutrients altogether, or eat only protective nutrients?
226 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 226
11 June 2015 7:57 PM
KEY SKILLS Nutrition and the NHPAs
Topic 10
FS
Concept 3
See more
Colorectal Cancer
See more
Obesity
Unit 3
AOS 1
Topic 10
See more
Osteoporosis
Concept 4
EC
TE
D
PA
G
E
PR
O
Many of the NHPAs, including cardiovascular health, diabetes mellitus, colorectal
cancer (from the cancer control NHPA), obesity and osteoporosis (from the arthritis
and musculoskeletal conditions NHPA) have nutrition as a significant risk factor.
To be able to explain the links between nutrients and these conditions, a
thorough understanding of the key nutrients examined in this chapter is essential,
along with a sound knowledge of the function and food sources for each one.
When studying the key nutrients, ensure you include the following:
• the roles the nutrient plays in increasing or decreasing the risk of the condition.
Some nutrients can be a risk and/or a protective factor for two different
conditions. Ensure you know the range of roles that each nutrient plays. Do not
restrict your knowledge to one or two NHPAs, as knowledge of all those listed
above may be required
• familiarity with a range of food sources. Be able to identify food sources of a
particular nutrient from a range of food groups. You may be asked to list a nondairy source of calcium, for example. If a food source has the nutrient added
artificially, state that it is a fortified food source (such as fortified breakfast cereal
being a source of vitamin D).
If an explanation of the role that nutrition plays as a protective factor against
osteoporosis were required, the following could be included.
People who consume enough nutrients for optimal bone health during years of
rapid growth (such as youth) and throughout other life span stages are less likely
to develop osteoporosis. Calcium and phosphorus❶ are essential for building peak
bone mass.❷ Calcium and phosphorus join together to make calcium phosphate,
the hardening material of bone.❸ In the right proportions, these nutrients can
assist in reducing the risk of osteoporosis. Major food sources for calcium include
milk, cheese, salmon (with bones) and fortified orange juice.❹ Major food sources
for phosphorus include milk,❺ eggs, chicken and beef.
Unit 3
AOS 1
O
KEY SKILL Explain the role of nutrition in addressing
specific conditions within the NHPAs, including the
functions and major food sources of relevant nutrients.
R
PRACTISE the key skills
O
R
1Discuss the role that fats can play in addressing cardiovascular disease.
2Explain the possible health consequences for an individual who consumes excess
sodium.
3Discuss the role that nutrition can play in addressing colorectal cancer.
U
N
C
Key skills exam practice
(© VCAA 2006, from the written exam paper, 2006, Q.4b).
Table 5.3 Disease burden attributable to overweight/obesity by condition, Victoria, 2001
Deaths
DALYs
% of total DALYs
Type 2 diabetes
Ischaemic heart disease
Condition
1 190
1 255
23 479
113 579
3.6
2.1
Osteoarthritis
Colorectal cancer
Hypertension
Ischaemic stroke
Total burden
5
217
146
124
2 937
3 130
3 130
1 301
5 255
149 874
0.4
0.5
0.5
0.8
7.9
❶ Simply listing the nutrients is a good
start, but some further explanation
is required; for example, ‘What role
does each nutrient play in promoting
health?’
❷ Key terms are used.
❸ The specific role of each nutrient is
explained.
❹ Major food sources are identified.
Source: Adapted from Department of Human Services 2005, Victorian Burden of Disease Study, Mortality and
Morbidity in 2001, Public Health Group, Rural and Regional Health and Aged Care Services Division, Victorian
Government Department of Human Services, Melbourne, p. 87.
❺ Specific food items are used instead
of food groups such as ‘dairy’.
Nutrition and the NHPAs • CHAPTER 5 227
c05NutritionAndTheNHPAs.indd 227
11 June 2015 7:57 PM
Key skills Nutrition and the NHPAs
FS
4(i)Nutrition can be a risk factor for each of the conditions in table 5.3. Choose one of
these conditions (except osteoarthritis) and show how a person’s food choices may
be a risk for developing that condition.
Condition chosen
Nutrition as a risk factor for this condition
U
N
C
O
R
R
EC
TE
D
PA
G
E
PR
O
O
(ii)Nutrition can be a protective factor for each of the conditions in table 5.3. Choose
one of these conditions (except osteoarthritis) and show how a person’s food choices
may protect them against developing that condition.
Condition chosen
Nutrition as a risk factor for this condition
2 + 2 = 4 marks
228 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 228
11 June 2015 7:57 PM
CHAPTER 5 review
Chapter summary
• Fibre is a type of carbohydrate that is essential for the health of the digestive system.
It does not contribute any energy to the body because it passes through without
being digested, reducing the risk of obesity. It can help reduce blood glucose and
cholesterol levels and decreases the risk of cardiovascular disease and colorectal
cancer.
Chapter 5 definitions
Searchlight ID: int-2918
PR
O
• The main function of protein is for the growth, repair and maintenance of body tissues.
It can also be used as a source of energy when carbohydrate intake is low. Excess
protein intake may contribute to weight gain and can decrease the amount of calcium
in the bones. Protein deficiency may also reduce bone density and increase the risk of
osteoporosis.
Interactivities:
Chapter 5 crossword
Searchlight ID: int-2917
FS
• The main function of carbohydrates is to provide the body with energy. They are the
body’s preferred source of energy and contribute 17 kilojoules per gram.
O
• There are six categories of nutrients required for optimal health: carbohydrates, protein,
fat, vitamins, minerals and water.
E
• The main function of fat is to provide a fuel for energy production. Each gram of fat
produces 37 kilojoules of energy, making it a more concentrated source of energy
than carbohydrates.
PA
G
• Monounsaturated fats decrease LDL or ‘bad’ cholesterol and play a part in protecting
people from cardiovascular disease.
Chapter 5 concept cards
HD34-031 to HD34-046
• Polyunsaturated fats increase HDL or ‘good’ cholesterol and decrease LDL cholesterol.
Polyunsaturated fats also reduce blood clotting and inflammation and decrease the risk
of cardiovascular disease as a result.
TE
D
• Trans and saturated fats increase LDL cholesterol and therefore increase the risk of
cardiovascular disease. Trans fats also interfere with cell membranes and can contribute
to impaired glucose regulation.
• Carbohydrates, protein and fat can all be stored as fat if not used for other functions.
This can increase the risk of obesity and related conditions such as cardiovascular
disease and type 2 diabetes.
EC
• If energy input is greater than energy output, weight gain results.
R
R
• Water makes up a majority of body weight and is required for a range of functions,
including for chemical reactions and as a key component of many cells, allowing
them to function effectively. Water contains no kilojoules and may assist with weight
management.
• Calcium and phosphorus work together to harden bones and teeth.
U
N
C
O
• Sodium assists in the regulation of fluid in the body and the functioning of
the nervous system. Too much sodium can lead to high blood pressure or
hypertension, and can also cause calcium to be excreted, therefore increasing the
risk of osteoporosis.
• Vitamin D assists in the absorption of calcium and phosphorus and is therefore
important for bone health. Vitamin D is generated in the body when the skin is
exposed to ultraviolet radiation.
• Nutrients such as saturated fats, trans fats and sodium are collectively termed risk
nutrients because if consumed in excess, they increase the risk of a range of health
conditions.
• Nutrients such as vitamin D, calcium and fibre are collectively termed
protective nutrients because they decrease the risk of developing a range of
health conditions.
• Nutrients are important factors in increasing or decreasing the risk of health
conditions within some NHPAs, including cardiovascular health, diabetes mellitus
(particularly type 2 and gestational diabetes), colorectal cancer, obesity and
osteoporosis.
Nutrition and the NHPAs • CHAPTER 5 229
c05NutritionAndTheNHPAs.indd 229
11 June 2015 7:57 PM
CHAPTER 5 review
APPLY your knowledge
1 Copy and complete the following table for each
nutrient covered in this chapter.
7 Are any nutrients both risk and protective nutrients?
Explain.
8 ‘Australia is a land of overconsumption, and eating
too much food causes all diet-related diseases in
this country.’ Write a response to this statement
using the knowledge you have gained in this
chapter.
9 Draw up a table with two columns. Label one
column ‘current foods’ and the other column
‘healthier options’. Write down everything you
eat in a day and suggest substitutes that could
improve your diet. Don’t forget to include drinks
and snacks.
10 Use the Vegetarianism links in the
Resources section of your eBookPLUS to
find the weblink and questions for this
activity.
11 Use the Fibre quiz links in the Resources
section of your eBookPLUS to find the
weblink and questions for this activity.
O
PR
O
U
N
C
O
R
R
EC
TE
D
PA
G
2 (a) Which nutrients are used as a fuel for energy?
(b) What health concerns may arise if these
nutrients are eaten in excess?
3 (a) What is the most abundant mineral in the body?
(b) What is it used for?
4 Explain why a balanced diet is the best option for
optimal health.
5 List three nutrients that contribute to cardiovascular
disease.
6 Explain how vitamin D can affect the health
of bones.
E
Possible
Possible
effects
effects
associated associated
Food
with
with
Nutrient Function sources deficiency
excess
FS
TEST your knowledge
230 UNIT 3 • Australia’s health
c05NutritionAndTheNHPAs.indd 230
11 June 2015 7:57 PM
TE
D
EC
R
R
O
C
U
N
E
PA
G
PR
O
O
FS