Unpleasant reactions to
food
© Food – a fact of life 2009
Extension
Learning objectives
• To understand there are many different reasons for
unpleasant reactions to food.
• To know which foods may cause a food intolerance
and/or allergy.
• To recognise the symptoms of food intolerance
and/or allergy.
• To understand the severity of peanut allergies.
• To recognise the seriousness of anaphylaxis.
• To understand the terms oral allergy syndrome and
exercise induced food allergy.
• To define the term food aversion.
• To understand the cause and effects of lactose
intolerance and coeliac disease.
© Food – a fact of life 2009
Food intolerance
Most people can eat foods
without any problems
although they may have
different likes or dislikes that
influence what they choose.
However, some people react
to certain foods and eating
them may cause
uncomfortable symptoms or,
in rare cases, a severe illness.
© Food – a fact of life 2009
Assistance with a food intolerance
It is important that people who think they suffer from a
food intolerance do not cut out important foods.
This could mean people miss out on important nutrients
and can affect the results of allergy tests.
Some allergy and intolerance tests are advertised in
magazines, in the shops and over the internet.
For many of these tests there is no evidence that they
are reliable.
© Food – a fact of life 2009
Assistance with a food intolerance
People with food intolerance or allergy concerns
should take advice from a doctor or dietitian to make
sure that the medical condition is properly diagnosed.
Care needs to be taken to ensure that their diet
contains a wide variety of foods to provide all the
nutrients they need, particularly the nutrient/s normally
provided by the foods they cannot eat.
It is important to consume a healthy and varied diet for
good health.
© Food – a fact of life 2009
The eatwell plate
The eatwell plate is the UK guide to help people
achieve a health and varied diet for good health.
© Food – a fact of life 2009
Reasons for food intolerance
There are many reasons for unpleasant reactions to
food. A general term for those that are not cause by
food poisoning are food intolerances.
Most unpleasant reactions to food are not true food
allergies.
A food allergy is one particular type of food
intolerance that involves the body’s immune system.
Food intolerances may cause uncomfortable
symptoms, but only true allergies involve the immune
system.
© Food – a fact of life 2009
Food allergies
The immune system is part of the body’s defence
system, as it protects against foreign organisms like
bacteria and viruses. In some people, I may also react
to substances in foods, or in the environment, e.g.
pollen or animal fur.
This abnormal reaction is known as an allergic reaction.
The symptoms of an allergic response may be very
similar to those of a food intolerance, but potentially
more severe. They can also resemble those of other
illnesses. Proper diagnosis, therefore, is very important.
© Food – a fact of life 2009
Causes of allergic reactions
Most foods may cause an allergy, but, listed below are
the most common allergic reactions to food in Europe.
These ingredients must be labelled on food packaging.
• celery;
• cereals containing
gluten (wheat, rye
barley and oats);
• fish, molluscs, and
crustaceans (including
prawns and crabs);
• lupin (seeds similar to
legumes);
• cow’s milk and milk
products.
© Food – a fact of life 2009
• mustard;
• nuts (including Brazil
nuts, hazelnuts, almonds,
and walnuts);
• peanuts
• sesame seeds;
• soya;
•sulphur dioxide or
sulphites (preservatives).
Children and food allergy
Allergies tend to run in families. The most common food
allergy reactions in childhood are to:
• eggs;
• cow’s milk and milk products;
• nuts (including peanuts);
• soya;
• wheat.
It is common for most children to grow out of food
allergies early in their childhood.
© Food – a fact of life 2009
Symptoms of food allergies
A food allergy usually occurs between a few minutes
and a few hours after eating a particular food.
The symptoms of food allergies vary from person to
person and can include:
• coughing;
• dry, itchy throat and tongue;
• nausea and feeling bloated;
• wheezing and shortness of breath;
• swelling of the lips and throat;
• runny or blocked nose;
• sore, red and itchy eyes.
© Food – a fact of life 2009
Peanut allergy
In extremely rare cases, a severe allergic reaction
called anaphylaxis can cause death.
An example of this is a serious
allergy to peanuts or other nuts.
Peanut allergy has become more common, especially
in children. Until recently, the UK government
recommends that, where there is a family history of
allergy, pregnant mothers should not eat peanuts, and
that peanuts are not given to infants.
© Food – a fact of life 2009
Anaphylaxis
A severe allergic reaction can sometimes lead to
anaphylaxis. When someone has an anaphylactic
reaction, they may have serious symptoms in different
parts of the body at the same time. These symptoms
can develop within minutes.
This severe reaction can be fatal if it is not treated
immediately. Treatment is usually an injection of
adrenaline (epinephrine). Most people with severe
allergies will have this with them whereever they go.
© Food – a fact of life 2009
Anaphylaxis
Anaphylaxis is most commonly
caused by food allergies, but
can also be caused by other
things, such as insect bites and
drug allergies.
Peanuts, milk, eggs and fish are
the most common foods to
cause anaphylaxis in the UK.
© Food – a fact of life 2009
Oral allergy syndrome
Foods such as fruit and vegetables can cause reactions
such as itching or rashes around the lips and mouth.
This is called oral allergy syndrome and is a symptom of
a food allergy. It is usually only seen in people who get
hay fever.
Cooking often destroys the allergies
that trigger this reaction, for
example people who react to raw
apple might be able to eat cooked
apple.
© Food – a fact of life 2009
Trends in intolerances and allergies
Food intolerance is more common in children than in
adults. Children often grow out of the problem before
they go to school.
The Food Standards Agency estimates that as many as
20% to 30% of people in the UK think they suffer from
some kind of food intolerance.
However, surveys have shown that only about 1- 2% of
adults in the UK have a food allergy that can be
detected by rigorous tests.
© Food – a fact of life 2009
Food aversion
Some people’s symptoms
only occur if they know that
they are eating a particular
food – they do not occur if
the food is disguised.
This is called food aversion.
It may be because they
believe the food will cause
symptoms, or because the
food has been associated
with illness in the past.
© Food – a fact of life 2009
Lactose intolerance
One type of food intolerance is
caused by the lack of an enzyme
that is needed to digest a
component of food.
The most common example of this is
lactose intolerance where sufferers
have low levels of the enzyme
needed to digest lactose, the sugar
found in milk. Lactase breaks down
the lactose so that it can be
absorbed.
© Food – a fact of life 2009
Lactose intolerance
Children are usually born with sufficient lactase but in
some parts of the world, levels fall rapidly after
childhood.
Lactose intolerance is typically seen in adults and is
more common in Africa, India and South America.
In the UK, Ireland and northern Europe, only 5% of the
population is affected, to varying degrees.
© Food – a fact of life 2009
Lactose intolerance
If lactase levels are low, undigested lactose passes into
the large intestine where it causes pain and diarrhoea.
Lactose intolerance is common in some ethnic groups,
particularly where adults do not traditionally drink milk.
People with lactose intolerance can usually drink small
amounts of milk, yoghurt and eat cheese without
problems.
If symptoms are severe, alternative sources of calcium
must be eaten.
© Food – a fact of life 2009
Coeliac disease
Coeliac disease is a reaction to gluten, a protein found
in cereals such as wheat, rye and barley.
The gluten damages the small intestine so people with
coeliac disease cannot absorb nutrients from food
normally. Sufferers typically have stomach pain and
diarrhoea after eating foods that contain gluten.
Coeliac disease is usually first noticed in childhood, but
can go undetected into adulthood. In order to diagnose
coeliac disease, patients need to be consuming gluten.
It is important that people seek medical advice rather
than simply changing their diet.
© Food – a fact of life 2009
Coeliac disease
The disease can affect growth or cause weight loss.
People with coeliac disease must avoid foods that
contain gluten throughout their life, for example, bread
cakes, and biscuits. Many foods have small amounts of
wheat, barley or rye added, so people with coeliac
disease must check food labels carefully.
Rice, maize and potatoes do not contain gluten so are
good sources of starchy carbohydrate , and glutenfree versions of foods such as bread and pasta are
available.
Coeliac disease may affect as many as 1 in 100
people in the UK; some of whom do not know they
have the disease.
© Food – a fact of life 2009
Review of the learning objectives
• To understand there are many different reasons for
unpleasant reactions to food.
• To know which foods may cause a food intolerance
and/or allergy.
• To recognise the symptoms of food intolerance
and/or allergy.
• To understand the severity of peanut allergies.
• To recognise the seriousness of anaphylaxis.
• To understand the terms oral allergy syndrome and
exercise induced food allergy.
• To define the term food aversion.
• To understand the cause and effects of lactose
intolerance and coeliac disease.
© Food – a fact of life 2009
For more information visit
www.nutrition.org.uk
www.foodafactoflife.org.uk
© Food – a fact of life 2009