What is a food allergy?

Food allergies are fortunately quite rare. They usually affect young children and people who suffer other allergies. Children occasionally become sensitive to foods, such as cow's milk and eggs during their first year of life. Luckily, most children will grow out of these sensitivities in a couple of years. However, if the child is allergic to nuts or fish it is unlikely that they will outgrow this allergy.

People with true food allergies have an unusually sensitive immune system, which occurs when the body's immune system overreacts to food, which is normally harmless. For some reason when they swallow a certain food the person's own antibodies rush into action, attacking the substance consumed. This starts a chain reaction of chemical changes, which cause the symptoms of an allergic reaction.

What is a food intolerance?

A food intolerance is a general term to describe a reaction to food that causes symptoms that may be unpleasant. Food poisoning, caused by toxic substances is not a food intolerance as it would have the same effect on anyone who ate the contaminated food.

Food allergy can be referred to as a food intolerance. Other food intolerances or food sensitivities are known as adverse food-induced reactions and they do not involve the immune system. This adverse reaction to food or an ingredient in food is what is commonly called a food intolerance. Food intolerance usually occurs in people who lack an enzyme necessary for the digestion of food. When they eat a certain food the body can't break it down and so a reaction occurs. The most common example of this is lactose intolerance. Sufferers lack the enzyme that is needed to digest lactose, the main sugar in milk. Another food intolerance is coeliac disease, where a person is unable to digest gluten, a protein found in cereals such as wheat and barley.

Is there a difference between an allergy and an intolerance?

It is quite difficult to differentiate between a true food allergy and food intolerance. Food intolerances like food allergies, are adverse reactions to foods. However, food intolerances do not involve your immune system. The actual number of those suffering from allergic reactions to foods is relatively small. The symptoms they experience are usually food intolerances.

Foods that may cause a reaction.

Food allergies can be caused by any food. However, the most common food allergens are milk, eggs, fish, peanuts, wheat and shellfish.

The most common food intolerances include foods such as dairy products, nuts, fish/shellfish, chocolate, soft fruits and yeast. A few people are allergic to certain food additives, such as E102 (tartrazine), E110 and E211. Food labels give information about most additives so that specific ones can be avoided if necessary.

The peanut and tree nuts (e.g. almonds, cashews and walnuts) are by far the most common cause of severe allergic reactions (anaphylaxis) though shellfish and dairy products have been known to cause anaphylaxis as well.

Food allergies are an inconvenience but they are manageable and with extra care and vigilance you can avoid the allergen and therefore avoid the associated symptoms.

What are the symptoms of food intolerances and food allergies?

It is easy to confuse a food intolerance with an allergy because both conditions can have similar symptoms. If you have a food intolerance you can usually eat a small amount of the offending food without it causing a problem. However, those who suffer severely from food allergies can experience symptoms after the smallest amount of food comes into contact with their lips or even their hands if touched. Symptoms typically occur, within minutes to 2 hours after the person has eaten the food to which they are allergic.

Symptoms of food intolerances can include:

• Diarrhoea and flatulence.
• Stomach pain.
• Nausea and vomiting.
• Fatigue.
• Migraines.
• Sleeplessness.

Symptoms of a food allergy may include:

• Swelling of the lips, face, tongue or throat - this may lead to suffocation .
• A tingling/itchy sensation in the mouth and lips.
• Stomach cramps.
• Feeling of weakness - caused by a drop in blood pressure.
• Vomiting and diarrhoea.
• Blotchy, itchy skin rashes.
• Headaches.

It is important that if you experience any kind of allergic reaction after eating (especially peanuts, nuts and seeds) that you contact your doctor for further advice and avoid that food until then. Even if the symptoms are mild this time, like a tingling lip, the next time you eat that food you might suffer a severe allergic reaction (anaphylaxis).

How can I find out what foods I am allergic to?

Diagnosing the onset of food allergies can be quite difficult. The help of a dietician is often needed. Tests, which are usually very time consuming will be carried out carefully. You will normally be asked to keep a record of what foods you have eaten over a period of weeks. This record will then be used to study if there is a relationship between the foods eaten and any symptoms experienced.

The dietician will normally want to introduce you to a strict diet, known as an elimination diet. The foods your dietician chooses are based on those least likely to cause you an allergic reaction, such as chicken, lamb, pears, carrots, sprouts, rice and potatoes. This process involves your diet being monitored to see if you can settle on the chosen diet, then slowly adding additional foods to your diet. With this method, the source of the problem should be recognised when a reaction occurs.

One of the most difficult problems you will encounter when on an elimination diet is eating prepared food, as it may be difficult to know if they contain the offending allergen. You will need to read the small print on all labels. Now thanks to a significant improvement in food labelling it is possible to identify which foods contain the substances you personally need to avoid.

Although this diet involves a great deal of effort and inconvenience, if you do discover an allergy then the removal of the offending item from your diet can make your life much more comfortable.

Skin testing and blood testing are also very effective ways in identifying food allergies. For more information on these two tests read the section "How are allergies diagnosed?" on the allergies page.

An elimination diet is also used in diagnosing food intolerances as blood and skin tests cannot diagnose a food intolerance.

What treatments are available for food allergies and intolerances?

In both adults and children the best treatment for food allergies is completely avoiding the food causing you the allergy or intolerance. As children get older many of their allergies disappear, but until you are sure of this, avoidance is the only successful treatment. At the same time as avoiding certain foods you must also remember to maintain a healthy balanced diet. This is especially important in young children whose growth rate can be damaged by a poor elimination diet. It is important that you do not tackle a food allergy problem without professional help from a dietician.

There are treatments available to relieve the symptoms that are not life threatening, such as itchiness, swelling of the lips and rashes. The most common drugs used for this are antihistamines and your doctor may prescribe them if he/she is confident your symptoms will always be mild. Antihistamines are not effective in the more severe allergic reactions, such as swelling of the mouth and a drop in blood pressure. Your chemist will also advise which antihistamine products are suitable and it may also be a good idea, to keep some of this medicine in your home and bag at all times.

If the situation is life threatening (anaphylaxis develops) the only effective treatment is adrenaline. Adrenaline acts quickly to improve the quality of breathing, regulate the heartbeat and reduce the swelling in the face. In order for the treatment to be effective it must be administered very quickly. If you have previously had a severe allergic reaction then you will probably be given an adrenaline kit to carry around with you. You must ensure that you always have the adrenaline kit with you and make sure you are comfortable using the one that has been prescribed to you. Adrenaline treatments you could be given may include the following:

• Medihaler-Epi - if the symptoms include swelling of the mouth a treatment called a Medihaler-Epi should be used. A Medihaler-Epi is an aerosol containing adrenaline, the requirement is usually 4 puffs sprayed into the mouth. This type of treatment is not suitable for widespread allergic reactions.
• Epipens - the treatment of severe allergic reactions to foods has been revolutionised by the introduction of the Epipen auto-injector. This device has a spring-activated needle and is designed to deliver a single 0.3mg dose of adrenaline into your muscle when the pen is pushed into your skin.
• Min-i-jets - the Min-i-jet works in the same way as the Epipen but consists of a 1ml disposable syringe and needle. The dose will need to be measured accurately, as a full syringe will deliver 1mg of adrenaline.

The majority of food allergy sufferers prefer the use of the Epipen due to the ease and the simplicity. There is no visible needle and the device has a shelf-life of 2 years compared to 9 months for the Mini-i-jet. In some cases a single dose of the Epipen may not prove enough to treat severe reactions, you should always carry two Epipens as a safety measure. If you are at risk from severe allergic reactions then you must carry medications around at all times.

Tips on avoiding the allergen

After you have been diagnosed with a food allergy the only cure at present, is total avoidance of all products containing the allergen.

One of the more common food allergies is to peanuts and so manufacturers are beginning to recognise the potential dangers a person allergic to peanuts faces. Therefore most foods containing peanuts are now clearly labelled ‘this product may contain nuts’.

Take time to check all food ingredients thoroughly, if you are unsure about the possible presence of your specific allergen in any foods you purchase and there is no advisory label, then it would be advisable to check the contents with the manufacturer. Also be careful when purchasing foods that you have eaten before, as recipes do sometimes change.

When eating out, remember to ask if any of the dishes you have ordered contain the food you are allergic to. If necessary ask to speak to the senior manager, remember the chef may be especially creative and throw in a handful of something extra for flavour or texture. Don’t worry about causing a fuss, explain what the food could do to you and if you are not happy with their answer, choose something else on the menu, or eat somewhere else. Chinese, Thai and Indian restaurants are best avoided if you have a peanut allergy.

Children and food allergies

An informed parent doesn’t need to live in fear if their child suffers from a food allergy. The more you understand about the situation the better you will feel. Remember, your child’s allergy will travel everywhere with them, to school, to friends houses', to parties and on holiday. If you tell everyone about the situation you are minimising your child's risk of an allergic reaction.

Foods to watch out for:

Many unsuspecting foods, drinks and snacks can contain foods that you should avoid such as nuts, milk, eggs, wheat, fish and soy. As an example foods that may contain nuts are as follows:

• Cakes
• Pastries and biscuits
• Sweets and chocolates
• Fruit yoghurts
• Vegetarian products such as veggie burgers.
• Salad dressings
• Chilli
• Peanut Butter
• Curries
• Dips
• Chinese
• Breakfast cereals
• Pesto and satay sauces
• Marzipan
• Ice cream
• Praline and nougat

If you are severely allergic to milk you should watch out for whey, whey powder, whey solids and lactose. Also when eating out be careful when eating steaks, many restaurants put butter on after they have been grilled to add extra flavour and it may not be visible once melted.

If you are severely allergic to eggs check food labels carefully for products containing egg or albumen (white of an egg). Commercially processed cooked pastas usually contain eggs, also be aware that eggs can sometimes be used to create the foam or milk topping in speciality coffee bars.

If you are severely allergic to shellfish and fish you should watch out for paella, Oriental foods, kedgeree, worcestershire sauce, steak sauce, Caesar salad and Caesar dressing.

Most supermarkets now have 'free from' lists. Explain your problem to your local supermarket and most will be pleased to help and give you advice.

Helpful Tips

Kissing - ask your partner if they have been eating the food you are allergic to, a reaction doesn’t necessarily mean you have to eat the food yourself, bodily contact can also cause a reaction.

Alcohol - extra care needs to be taken when consuming alcohol, as your judgement of certain foods can sometimes be altered.

Chocolates - don’t be embarrassed about saying no, if you are unsure about the ingredients.

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