Food allergies: the facts

May 9th 2019

What is a food allergy?

A food allergy reaction can range from a blocked nose or hives, to vomiting or difficulty breathing, to anaphylaxis. These reactions happen after eating a particular food that causes the immune system to mount an attack against the ‘enemy’ food. When this food is consumed again, the antibodies previously created will trigger and kick-start the allergic reaction.

However, the severity of a reaction will differ each time a person comes into contact with that food, making it impossible to predict how someone will react. For instance, a person may have a sever reaction one time, but a mild case the next, and vice versa.

And for those that have experienced a severe allergic reaction in which it became anaphylaxis, their lives are spent on high alert ensuring absolute care with everything they consume, in a bid to avoid this potentially life-threatening reaction from happening again. Allergies can have a huge impact on quality of life and in very rare cases, be fatal.

Why are food allergies on the rise?

For reasons that are unclear, rates of food allergies have risen sharply in the last 20 years. Theories to this rising issue are around environmental influences such as better hygiene, lack of vitamin D, pollution, gut problems and changes to the nation’s diet that have been seen over the past couple of decades.

What foods can cause an allergic reaction?

Although any food can cause an allergic reaction, the main foods that most commonly cause a reaction include:

  • Fish
  • Eggs
  • Shellfish
  • Milk
  • Peanuts
  • Tree nuts (walnuts, almonds, pine nuts, brazil nuts, pecans
  • Sesame
  • Soya

When can food allergies develop?

Any person can develop an allergic reaction at any age, however, most food allergies affect children under the age of three. Some children are likely to grow out of their food allergy to milk, soya or eggs by the time they begin school, but children with peanut or tree nut allergies are likely to remain allergic to these for the rest of their lives.

Allergies that develop in adulthood are also likely to be lifelong and can occur with foods once tolerated.

What’s the difference between a food allergy and a food intolerance?

A food allergy is not the same as a food intolerance. An allergy to a particular food causes a reaction from the immune system with symptoms such as itching inside and around the mouth, throat or ears, swelling of the face around the eyes, lips, tongue and roof of the mouth, vomiting and difficulty breathing. A food intolerance is a difficulty to digest certain foods causing uncomfortable reactions such as bloating, diarrhoea, itching or rash of the skin.

How can food allergy reactions be avoided and treated?

The best way of preventing an allergic reaction is to identify the food that causes the allergy and avoid it.

Research is underway looking at ways to desensitise some food allergens, such as peanuts and milk, but this is not an established treatment.

Avoid making any radical changes, such as cutting out dairy products, to your or your child's diet without first talking to your GP.

Antihistamines can help relieve the symptoms of a mild or moderate allergic reaction. A higher dose of antihistamine is often needed to control acute allergic symptoms.

Adrenaline is an effective treatment for more severe allergic symptoms, such as anaphylaxis.

People with a food allergy are often given a device known as an auto-injector pen, which contains doses of adrenaline that can be used in emergencies.

How can food intolerance reactions be avoided and treated?

If you're confident you are intolerant to a particular food, the only way you can manage this is to:

  • Keep a food diary to work out what food you are intolerant to
  • stop eating the food for a while, and then
  • reintroduce small quantities while monitoring how much you can eat without symptoms coming on.

If symptoms do come on, antihistamines can help relieve digestive issues and itching skin or rashes.

If you think your child may have a food intolerance, check with your GP or a dietitian before eliminating foods from their diet, as a restricted diet could affect their growth and development. Cows' milk, for example, is an important source of calcium, vitamin D and protein.