Transcript Human Nutrition and Health - IBDPBiology-Dnl

Option A:
Human Nutrition and Health
A.1 Components of the human diet.
Study Questions:
Red through your textbook & study guide and
answer these questions in full sentences:
 What are nutrients?
 What are essential nutrients?
 Give 2 examples of essential amino acids
 Give 2 examples of essential fatty acids
 Give 2 examples of essential minerals
 Give 2 examples of essential Vitamins
 Why is water so important in the diet?
 What are non-essential amino acids? Give 2
examples.
A.1 Components of the human diet.
 Define nutrient


A nutrient is a chemical substance found in
foods that is used in the body
Example of nutrients in human:
 Carbohydrates;
 proteins;
 lipids (fats & oils);
 vitamins;
 dietary fibre;
 dietary minerals &
 water.
•4
Essential nutrients in the human diet
 Nutrients that can not be synthesized by the
body from other nutrients thus they must be
included in the diet
 Examples:
 amino acids e.g. Phenylalanine &
methionine;
 fatty acids e.g. omega 3 & omega 6;
 Minerals e.g. K, Na, Fe, Ca, P, I;
 vitamins e.g. A, B, C, D & folate and
 water.
Non-essential nutrients in humans:
 Nutrients that can be synthesized by the body
from essential nutrients or obtained from
alternative sources. Dietary intake of nonessential nutrients reduces the need for
biosynthesis thus saving the body energy.
 Examples:
 amino acid e.g. tyrosine & alanine;
 Carbohydrates (energy can be obtained from
lipids & proteins);
 Vitamins e.g. E & K
Biosynthesis:
the production of
non-essential
nutrients in the
body from
components of
essential nutrients,
if these nutrients
are present in the
diet, the body does
not need to expend
the energy on
biosynthesis.
What is Malnutrition?
 the condition that results from taking an
unbalanced diet in which certain nutrients are
either lacking, in excess or in the wrong proportions
 Examples of malnutrition:
 Not enough food – starvation causing marasmus
 Too much food – overeating causing obesity
 Not the right type of food – protein malnutrition
causing kwashiorkor
 All types of malnutrition lead to health problems.
Malnutrition:
Consequences of protein deficiency
malnutrition :- Kwashiorkor
 These children are
suffering from
Kwashiorkor –
protein deficiency.
 Explain why the
children have
swollen abdomens.
 Too low intake of protein could lead to protein deficiency
malnutrition - a lack of essential amino acids.
 Essential amino acids are required for production of
proteins, such as plasma proteins, extracellular proteins,
DNA and plasma membranes in the body.
 Protein deficiency malnutrition is a key factor in
kwashiorkor.
 Symptoms of kwashiorkor include:
 Stunted growth
 Muscle and skin problems
 Impaired mental development
 Immune system impairment
 Edema (swelling in the abdomen and legs)
IB Exam Revision Questions:
 (a) Outline the consequences of protein deficiency
malnutrition.
[2]
Phenylketonuria (PKU)
Red through your textbook & study guide and
answer the following questions in full:
1. What causes PKU?
2.What enzyme are sufferers of PKU unable
to produce? What are the consequences
of this (explain in full)?
3.How can PKU be controlled by early
diagnosis?
4.How can PKU be controlled by diet?
Phenylketonuria (PKU):
 PKU is a genetic disorder that
is characterized by an
inability of the body to utilize
the essential amino acid –
phenylalanine.
 It is caused by a mis-sense
mutation in the PAH
(phenylalanine hydroxylase)
gene that codes for the
enzyme tyrosine hydroxylase
 Phenylalanine cannot be
converted to tyrosine, so it
builds up to dangerous levels.
 PKU is progressive disorder i.e. its effects
build up over time and lead to ongoing
deterioration.
 Symptoms of PKU:
 skin disorders;
 intellectual disability;
 heart problems;
 microcephaly ( neurodevelopmental
disorder in which the circumference of the
head is smaller than that of an average
person of the same age and sex) can also
develop in severe cases.
PKU Diagnosis: PKU Treatment:
 A blood test at birth
 A phenylalanine
will detect the presence controlled diet is used
or absence of the
from. Foods containing
enzyme tyrosine
phenylalanine such as
hydroxalase.
dairy, aspartame
sweeteners, breast milk,
 As PKU is a cumulative
nuts and meat are
disorder, the earlier it
minimized.
is diagnosed and the
diet is started, the less  Tyrosine rich foods such
chance there is of
as wheat, oats, banana,
severe complications.
avocado, beans, sesame,
pumpkins may be used.
IB Exam Revision Questions:
 (a) Explain how a special diet can reduce the
consequences of phenylketonuria (PKU).
 (b)
[4]
Variation in the molecular structure of fatty acids
 Fatty acids have the same general
structure, but there is variation in the
bonds between carbon atoms.
 Saturated fatty acids have no C-C
double bonds: all possible valences
have been occupied.
 A mono-unsaturated fatty acid has
C=C double bond.
 Polyunsaturated fatty acid has two or
more C=C double bonds.
Unsaturated fatty acids
 Unsaturated fatty acids
varies in their structure:
 cis- isomers have the
hydrogen atoms on the
same side of the C=C
double bond;
 trans- isomers have the
hydrogen atoms on
opposite sides.
 Most trans- fatty acids are
created artificially
through hydrogenation.
 In unsaturated fatty acids,
the omega-number
indicates the position of the
first double bond, from the
CH3 group.
 An omega-3 fatty acid has
the C=C double bond at the
third bond along the chain.
 Oleic acid
(CH3(CH2)7CH=CH(CH2)7
COOH) is an omega-9 fatty
acid, it is a component of
olive oil in its cis- form.
 Hydrogenation is a
process which is used to
create trans- fatty acids
from cis- fatty acids.
 Hydrogen is used to
saturate some of the
double bonds in an oil,
making solid fats from
liquid oils e.g. making
margarine from vegetable
oil.
 Oleic acid isomer, elaidic
acid (trans-oleic acid) is
found in hydrogenated
vegetable oil.
Copy and complete this table to outline the differences
between the different structures of fatty acids:
Name of fatty acid
Saturated fatty acids
Cis unsaturated
fatty acids
Trans unsaturated
fatty acids
Mono unsaturated
fatty acids
Poly unsaturated
fatty acids
Diagram of
structure
Description of
structure
Foods that
contain them
Health
implications
Health consequences of diets rich in the
various types of fatty acid:
IB Exam Revision Questions:
 (a) Explain possible health consequences of diets rich
in fats.
[2]
 (b) Outline the variation in the structure of fatty acids.
[3]
 (c) Explain why the difference between saturated fats
and unsaturated fats is important in a healthy diet. [3]
Fat diets across the world: introduction
 Read your textbook pp 210-213, your guide pp 111 &
search the internet
(http://www.ific.org/foodinsight/2005/jf/fatconsfi105.cfm?
renderforprint=1)and answer the following questions:
 What are the benefits of eating eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA) from
fish and fish oils?
 What is hydrogenation? Why is it done?
 HDL stands for High Density Lipoproteins (often
called “good cholesterol). LDL stands for Low
Density Lipoproteins (“bad cholesterol). Using this
information, explain why hydrogenation is thought
to be bad for health.
Fat diets across the world: Mediterranean diets
 How does eating a diet rich in olive oil help
reduce the levels of Coronary Heart Disease
(CHD) in Mediterranean populations?
 What else is in the Mediterranean diet that
might help reduce CHD? How does the
article say they protect cells from damage?
 What are the other benefits of
MonoUnsaturated Fatty Acid (MUFA)?
Fat diets across the world: Eskimo and
Japanese diets
 Give 3 examples of fatty, cold-water fish. What
useful substances do they contain?
 What health benefits might this account for?
 How can you tell that it is not just Japanese
genetics that gives them these health benefits?
 What study led experts in the US to define a
weekly consumption of 1-2 servings of fish as
consistent with good health?
Fat diets across the world: Analyzing the
studies
 Summarise the other dietary components
and non-dietary factors that contribute to
the health and well-being of the
Mediterranean and Japanese ethnic groups.
 Do you think there is enough evidence to
support the claims made by the studies in
the Mediterranean and Japan? Look at this
website (http://www.stop-transfat.com/benefits-of
saturated_fats.html)before you answer!
Vitamins and Minerals
 Distinguish between the chemical structure of
Vitamins and Minerals – use Page 194 of your text
book.
 What does RDI stand for?
 What is the older method for calculating RDI?
 What is the more modern method?
Vitamins
 Vitamins are
organic compounds
made by plants or
animals
 e.g. vitamin C
Minerals
 minerals are
inorganic ions they
can be found in
water, soil and many
organic food types
as a result of uptake
 e.g. K+, Na+, Ca2+,
Fe2+, P & I-
IB Exam Revision Questions:
 (a) Distinguish between minerals and vitamins in
terms of their chemical nature.
[2]
Vitamin C (Ascorbic Acid):
 Read your text book Pp 214-216, your guide pp 110 and
webpage
(http://www.healthyeatingclub.com/info/books-
phds/books/foodfacts/html/data/data4i.html) then
answer the following questions:
 What is the Vitamin C deficiency disease? Discuss
how to cure it.
 What is the difference between RDI, RDA and DRI?
 How much Vitamin C is needed to “saturate” the
body? What happens to any excess?
 The RDA of Vitamin C has changed over the years.
Why?
 What are the benefits and dangers / adverse effects of
taking more than the RDI of Vitamin C? (Give
details)
 Vitamin C is essential in the human diet.
 It maintains mucus membranes as a component of
collagen, and promoted healing and skin growth.
 Deficiency of vitamin C can lead to scurvy,
characterized by bleeding hair follicles, gums and liver
spots on the skin. In extreme cases it can be fatal.
 Recommended Daily Intakes (RDI) of vitamin C have
been set at 45-60mg day-1.
 These levels were determined based on a number of
experiments into levels of vitamin C that gave optimum
benefit.
 Humans and guinea pigs cannot synthesize vitamin C,
so it is possible to measure the effects of varying vitamin
C doses in carefully controlled experiments.
Human trials:
 Conscientious objectors from WWII volunteered to
take part in a series of medical trials in Sheffield over a
four-year period.
 symptomatic effects of varying doses of vitamin C
supplementation were observed
 Experiment:
 20 volunteers were used to measure the effects of
varying vitamin C concentrations.
 Weeks 1-6: No vitamin C in foods, but all given 70mg
supplement
 Weeks 7-end (8 months): 3 kept on 70mg per day, 7 were
given 10mg per day and 10 were given no vitamin C at all.
 Measurement:
 periodic incisions were made on volunteer’s thighs, and
healing time and strength of healed tissue were
observed.
 Blood and urine vitamin C concentrations were
recorded.
 Outcomes:
 no ill effects were recorded in the 70mg or 10mg groups.
 The 0mg group developed scurvy within 6-8 months
and some serious side effects were recorded, including
one who experienced heart problems, which were
rectified after he was given vitamin C.
Guinea pig trials:
 Observation of the effect of vitamin C concentration
on collagen structure
 After periods of varying vitamin C supplementation
and measurement of blood and urine vitamin C levels,
guinea pigs were sacrificed and the structure of
collagen fibres observed.
 Guinea pigs with restricted vitamin C showed weaker
collagen.
Recommended Daily Intakes (RDI) of vitamin C
 Based on controlled experiments using human and
animal subjects, RDI of vitamin C have been set at 45-60
mg day-1
 There is some debate on whether the RDI should be
higher, with experts such as:
 Nobel-winner Linus Pauling suggesting that mega doses
(1000 mg or more) are required per day;
 The Vitamin C Foundation recommend 3 doses of 1000 mg
per day.
 The evidence for the efficacy of these recommendations is
not strong, yet some have suggested it can boost the
immune system, prevent upper respiratory tract
infections, decrease susceptibility to cancer and speed
healing and recovery from illness.
Danger of rebound vitamin C malnutrition.
 Some adverse effects of high dose vitamin C regimes
can include intestinal problems and acidosis, but there
is little data to suggest long-term harm.
 It has also been suggested that rebound malnutrition
can occur as a result of systemic conditioning during
long periods of high-dose supplementation: the body
is accustomed to excreting large amounts of vitamin C
and this continues once supplementation stops,
leading to deficiency.
 The evidence for these claims is also weak.
IB Exam Revision Questions:
 (a) Outline a method used to determine the
recommended daily intake of vitamin C.
 (b) Discuss the amount of vitamin C that adults
should consume per day.
[3]
[4]
Vitamin D:
Questions:
Answer
Vitamin D is soluble in?
Vitamin D is needed for?
Where is vitamin D is made?
What else is needed to make it?
What foods contain vitamin D?
What are vitamin D deficiency
disease in children?
What are vitamin D deficiency
diseases in adults?
Issues surrounding getting
sufficient Vitamin D to avoid
deficiency disease
Name:
Description:
Names:
Description:
Sources of vitamin D in human diets:
 Vitamin D can be produced by skin on exposure to UV
light from sunlight. (next slide)**
 It also can be found (in a slightly different form) in
foods:
 fatty fish e.g. Nile perch, lung fish, cat fish;
 fish oils e.g. cod liver oil & fish liver oil;
 fortified cereal;
 eggs yolk and
 dairy product e.g. milk, cheese & yoghurt.
 In some countries, milk is supplemented with vitamin
D.
Exposure to sunlight as a source of vitamin D:
 UV light from sunlight on skin causes chemical
production of vitamin D
 UV light is too low in winter in high latitudes
 Vitamin D is stored in liver so the body can make
enough to last several months through winter
 Too much UV light can damage skin and cause skin
cancer so exposure needs to be limited
 Use of sun-block will inhibit vitamin D production;
 Covering skin with clothing prevents UV light from
reaching the skin
IB Exam Revision Questions:
 (a) List two dietary sources of vitamin D.
[1]
 (b) Discuss exposure to sunlight as a source of vitamin D.
[3]
 (c) Suggest how environmental conditions cause
malnutrition
[2]
Dietary supplements

Iodine is an essential mineral in the diet. In many
parts of the world children show symptoms of
iodine deficiency. Find out the answers to these
questions:
1. How is iodine used in the human body?
2. What are the symptoms of iodine deficiency?
3. What would be the benefits of dietary
supplementation with iodine?
4. Would it be feasible to develop a world wide
programme of dietary iodine supplementation?
5. Are there other mineral deficiencies that are
widespread causes of malnutrition?
IB Exam Revision Questions:
 ( a) Explain the benefits of artificial supplementation
of iodine in the diet.
[3]
Importance of fibre as a component of a
balanced diet.
 Dietary fibre includes the components of foods which
cannot be digested by the human body, largely
cellulose, a structural component of the plant cell wall.
 Dietary fibre plays important roles in human body
such as:
 Provides bulk in food, allowing one to feel full when




eating
Helps regulate blood sugar
Reduces blood cholesterol
Strengthens action of peristalsis in the intestine
Reduces constipation
IB Exam Revision Questions:
 (a)Explain the importance of fibre in the diet.
 (b)
[2]
A.2 Energy in human diets
Comparison of energy content per
100 g of carbohydrate, fat and protein
Type of Nutrient
Energy content
Kj/100g
carbohydrate
1760
fat
4000
protein
1720
 Various units of energy
can be used on food
labels, but we use the
unit kJ (kilojoules).
 One food Calorie is
equivalent to 4.18kJ.
 Note that fats contain
more than double the
energy per unit mass
than carbohydrates or
proteins.
Comparison of main dietary sources of
energy in different ethnic groups.
 Dietary energy can
come from various
sources, carbohydrates,
proteins or fats,
depending on the foods
available to a
population.
 Staple foods make up
the bulk of a
population’s diet, and
are generally crops.
Map showing some of the main staple crops around the world
Possible health consequences of diets rich in
carbohydrates, fats and proteins:
Energy and Ethnicity:
 Staple foods is a food that is eaten regularly and in
such quantities as to constitute the dominant part of
the diet and supply a major proportion of energy and
nutrient needs.
 Different cultures have different staple foods due to
availability, cultural preferences, wealth, life style and
traditions.
 Diets high in carbohydrates or proteins or fats can
affect health in different ways
 Make a table showing different staple foods from
around the world and the cultures that eat them.
Health consequences of diet
 Rearrange this table so the information it shows is
correct:
Diet contains lots
of…
Health consequences
Fat
Makes you feel full faster and for longer. Can also be
used for energy if necessary although this does
require the kidneys to excrete more urea which could
damage them.
Protein
Provides lots of energy which is beneficial before a
big sporting event. Excess can be turned into fat
causing obesity.
Carbohydrate
Contains lots of energy which could cause obesity.
Also linked to cancer of the colon.
IB Exam Revision Questions:
 (a) Compare the energy content of carbohydrate,
protein and fat.
[2]
Function of the appetite control centre in
the brain:
 Appetite is controlled in the hypothalamus of the brain by
both nervous and hormonal.
 Some hormones trigger appetite-stimulating neurons
while others trigger appetite-inhibiting neurons.
 An empty stomach releases the hormone gherin, which
triggers appetite-stimulating hormones, leading to
hunger.
 When food enters the stomach, gherin production is
stopped, reducing hunger.
 Appetite is also inhibited when:
 Food entering the intestine stimulates release of PYY3-36
hormone.
 Carbohydrate and protein digestion stimulate release of
insulin hormone from the pancreas.
 Fat storage stimulates release of leptin hormone from the
pancreas. This is enhanced by insulin.
 These three hormones trigger appetite-inhibiting neurons
in the appetite control centre in hypothalamus of the
brain.
 When sufficiently stimulated, the appetite control centre
sends nerve signals to another region of brain to create a
feeling of “being full”
 There are strong links to malfunction of any of these
pathways and obesity, as the individual eats more than is
required.
Appetite control
 Copy and complete the flow chart on the next slide to
explain how appetite is controlled in the brain
 Add annotations to explain what happens when parts
of this system stop working.
Start eating
Hormones from ___________
and __________
travel via the blood to the…
The ______ _______ _______
in the ________ in the brain
detects that no more food
needs to be eaten.
Stop eating
_______ Gene creates
leptin in _______ tissue
__________ tissue
sends ________ to the
brain to tell it________
___________________
___________________
IB Exam Revision Questions:
 (a) Outline how appetite is controlled.
[3]
 (b) Outline the role of the brain in how appetite is
controlled.
[2]
Body Mass Index:
 Do a survey of your friends, school mates and family
members and work out their BMI. (Ask permission
first!).
 Investigate one of the following R.Q:
 Is being underweight in humans (Homo sapiens),
dependent on age?
or
 Is being overweight in humans (Homo sapiens),
dependent on gender?
 Present your findings in a lab report, DCP & CE
criteria will be assessed.
 Classify your participants as underweight, normal
weight, overweight or obese using the BMI categories
in the textbook page 225.
Work out the BMI of the following people:
Participant
Name
Sarah
Mass
(kg)
70
Height (m)
John
60
1.85
Jacob
67
1.50
Ann
63
1.70
1.40
BMI
Obesity is on the increase. Why?
 State and
explain four
reasons for the
trend in the
data shown on
the graph.
 Use assessment
statement
A.2.7 on p 220
of your
textbook to
guide you.
Reasons for increasing rates of clinical
obesity in some countries;
 Clinical obesity is an excess of body fat generally
caused by consuming more energy than is used in
activity, with the excess stored as body fat.
 Sometimes obesity is caused due to mutation of
the leptin gene resulting in overeating.
 Obesity carries a reduced life expectancy, high
risks of CHD, diabetes, heart attacks and strokes.
 The obesity epidemic is on the steady increase
globally, in developed nations in particular.
IB Exam Revision Questions:
 (a) Outline the reasons for increasing rates of clinical
obesity in some countries.
[3]
Anorexia nervosa
 Anorexia nervosa is an eating disorder in which someone
has firm conviction that he/she is overweight even when
their BMI indicate that they are normal or underweight.
 Anorexia affects mainly teenage girls & women but also
affects few boys and men.
 Someone who has anorexia becomes chronically
underweight because of following strict a diet and
exercise pattern.
 What are the physiological consequences (effects on the
body) of anorexia in relation to:






Muscle mass?
Hair growth?
Blood pressure?
Fertility?
Menstruation?
Dental health?
Anorexia nervosa
 What are the consequences for the family and
friends of someone who develops anorexia?
 Read this article: http://www.mediaawareness.ca/english/issues/stereotyping/women
_and_girls/women_beauty.cfm
 What are your views on magazines using young ultra
thin models for advertising?
 Is it acceptable?
 What could the consequences be?
 How can we build a society where healthy body shape is
valued?
Consequences of anorexia nervosa
 Hormonal imbalance; periods
stops, problems in pregnancy,
growth & development
 Mental health; mood swings,
phobias & paranoia
 Muscle & bone; loss of muscle
mass, lack of strength &
osteoporosis
 Circulatory system; anemia,
heart weakness & circulatory
problems
 Immunity & healing; susceptible
to infections, healing is
impaired.
IB Exam Revision Questions:
 (a) Describe the consequences of anorexia nervosa. [2]
 (b)
A.3 Special issues in human nutrition
Breast feeding
 Design a leaflet to persuade new mothers to
breastfeed their babies rather than use
formula (artificial) milk.
 It should include:
 The difference between breast and
artificial milk
 The benefits of breast feeding
 Reassurance that breast feeding in public
is acceptable
 This should be a biased piece of writing!
Breastfeeding
 Read the article on this website:
 http://www.breastfeeding.com/advoca
cy/advocacy_boycott.html
 Explain as fully as you can the reasons
why someone may boycott buying
Nestle products.
 Are you convinced to boycott Nestle?
Breast feeding
 Remember – breastfeeding doesn’t
work out for every mother!
 Read this article for a (slightly) less
biased view!)
 http://kidshealth.org/parent/growth
/feeding/breast_bottle_feeding.html
Differences in composition between human milk
and artificial milk used for bottle-feeding babies
Human milk
Artificial milk
 contains human proteins
 contains soya or bovine
 fatty acids are derived from
human butterfat
 has antibodies thus provides
immunity
 contains lactose
 Contains less iron




proteins
fatty acids are derived from
vegetable oils
No antibodies thus does not
provide immunity
Does not contain lactose
contains more iron
Benefits of breastfeeding.
IB Exam Revision Questions:
 (a) Distinguish between the composition of human
milk and artificial milk for bottle-feeding babies.
 (b)
[2]
 Type II diabetes also called
adult-onset diabetes as it
generally manifests in
adulthood.
 Receptors on the target cell
such as liver cells become
resistant to insulin produced
by the pancreas, leading to
failure by the body to
correctly regulate blood
glucose.
 It is common in people aged
over 35 years, often in those
who have become overweight or obese.
Diabetes
 The cause and treatment of Diabetes is covered in
the core syllabus in sections 6.5.11 and 6.5.12.
 You may like to read Pg 196 in your text book & pg
55 in your guide to get an overview.
 Briefly outline the difference between Type I and
Type II diabetes (you do not have to give any
details of the cause or treatment).
 How can the two types of diabetes be managed
(controlled)?
Type II Diabetes

1.
2.
3.
4.
5.
Read Pp 233 - 234 in your text book and pp 113 of
your guide, then answer the following questions:
What are the other names of type II diabetes?
What are the causes of type II diabetes?
What are the symptoms of Type II diabetes?
What dietary advice is given to people with Type II
diabetes?
Which ethical groups have higher incidences of type
II diabetes?
Causes of type II Diabetes:
 body becomes resistant i.e. not responsive to insulin
 pancreas does not produce enough insulin
 dietary factors e.g. prolonged intake of high-energy
foods
 genetic predisposition certain ethnic groups e.g. Pima
Indians are more prone (50% of people aged 30 years &
above)
 lack of exercise, there is a very strong link of type II
diabetes with obesity
Symptoms of Type II Diabetes:
 high glucose content in blood (hyperglycemia)
 Feeling thirsty all the time
 frequent urination
 slow-healing sores (wounds)
 Tiredness (fatigue)
 Red swollen gums
 blurred vision, blindness in extreme cases
 Kidney & back pains
 nerve damage
 glucose in urine
 erectile dysfunction
Dietary advice to patients with type II
diabetes:
 moderate portions of food to avoid fluctuations in
blood sugar levels
 regular mealtimes to avoid fluctuations in blood
sugar levels
 include unrefined carbohydrates because they are
more slowly absorbed
 include carbohydrates with a low glycemic index
 include fibre-rich foods to slow absorption of
sugar
 limit saturated & trans fats because diabetes
increases risk of coronary heart disease
IB Exam Revision Questions:
 (a) State one cause of type II diabetes.
[1]
 (b) List two symptoms in a patient with type II
diabetes.
 (c) Outline the causes and symptoms of type II
diabetes.
[2]
[4]
Animal food products
Ethical issues concerning the of eating
of animal food products:
 Animal products such as honey; milk; eggs &
meat are a major component of the human diet;
 Animal products provide energy, protein, fatty
acids, dietary minerals & vitamins though they are
not without their;
 As human population grow, demand for food
increases, including animal products raising
certain ethical concerns;
 Concerns include ethical treatment of animals and
environmental sustainability.
 Religious reasons;
 Islam & Judaism do not eat meat from certain animals such as pig and
animals has to be slaughtered in a certain (non-violence) way
 Environmental reasons;
 More grains needed to feed animals for meat production, hence more
land needed thus clearing more rainforests to create farmland
 Ethical reasons;
 Bio-industry does not give animals decent life
 Transporting animals cause a lot of stress to them
 Some slaughtering procedures cause animals a lot of stress & pain
 Health reasons;
 People belief that it is healthier to avoid animal products
 Economic reasons;
 Animal products such as meat are relatively expensive than plant
products in certain countries
To Meat or not to Meat
 Explain why some people prefer not to eat animals or
animal products.
Cholesterol and heart disease

Read P 235 in your textbook & your guide p 114,
then answer the following questions:
1. What is cholesterol?
2. What is cholesterol needed for?
3. Explain how cholesterol can cause a heart attack
or stroke.
4. Explain the change in thinking about the
relationship between dietary cholesterol and
serum (blood) cholesterol.
5. How is cholesterol transported in the blood?
6. Complete the diagrams on the next two slides.
Benefits of reducing dietary cholesterol in
lowering the risk of coronary heart disease
 Cholesterol is needed in small amounts in the body to
produce steroid hormones and plasma membranes.
 Excess cholesterol is thought to contribute to
atherosclerosis by forming deposits in the arteries.
 Although there is some risk of cholesterol leading to
CHD, other risks factors such as smoking, inactivity, high
blood pressure and heredity are much stronger and more
closely related to CHD.
 Dietary cholesterol is not necessarily converted into
plasma cholesterol such as HDL (not harmful), or LDL
(harmful).
 Extreme intakes of cholesterol may lead to a greater
buildup of LDL in atherosclerosis.
Transport of cholesterol
Cholesterol
in blood
•
•
•
•
•
•
Transported by
__________ (good
cholesterol)
Liver
Cholesterol
broken
down
Can be increased by:
E__________
Not s__________
W________ loss
Omega 3, _________________________
A diet containing a lot of _________ and limited
amounts of _______.
• Moderate use of a__________??? (not proven!)
Transport of cholesterol
Transported by
__________ (bad
cholesterol)
Cholesterol
in blood
Cholesterol
can cause
plaques
•
•
•
•
•
•
Liver
Can be increased by:
No E__________
S__________
Putting on w________
trans _________________
A diet containing too little _________ and
lots of _______.
Food miles
 Read the article on this website:
http://www.bbc.co.uk/food/food_matters/foodmiles.s
html
 Discuss the concept of food miles and the reasons for
consumers choosing foods to minimize food miles
Concept of food miles:
 Is a measure of the distance the food is transported from site
of production to the consumer
 It is used to assess environmental impact of food we eat
 Locally produced food has lower environmental impact
 Some imported foods cost more in energy per gram for their
transport than they provide to the consumer
 Food miles does not take into account number of trips from
source& other costs such as machinery used, fertilizers, &
pesticides which may also need to be transported from where
they are produced to the farms
 Transportation is associated with CO2 emissions, with some
transport producing more than others e.g. planes
 During famine & natural disasters transport of food is
justifiable whatever the food miles on humanitarian grounds
Should consumers choose foods to
minimize food miles?
Advantages:
Disadvantages:
 less consumption of
 reduction in choice i.e. less
aviation fuel , so less fossil
fuel used per food unit;
 Reduction in air pollution
& road congestion;
 food will be fresher since it
is produced locally;
access to exotic foods;
 reduction in access to
foods out of season;
 reduced international
trade between developed
and developing countries;
 might be more expensive
in short-term;
How far should
we transport
food and in
which
circumstances
should we do it?
IB Exam Revision Questions:
 (a) Outline the concept of food miles.
[2]
 (b) Discuss whether consumers should choose foods to
minimize food miles.
[3]