Food allergy symptoms and diagnosis

Food allergies - peanuts

This article on food allergy symptoms and diagnosis gives great advice and information on allergies and nutrition for families in New Zealand.

What is a food allergy?

Allergies of any type can affect one in three of us at some stage during our life. It is estimated that between 5 – 8% of children have a food allergy (source: Allergy New Zealand).

The risk of a child developing an allergy increases if either of the parents have a history of allergies. A history of allergies includes asthma, hay fever, eczema and dermatitis. While specific allergies are not inherited the tendency to be allergic is inherited.

The most common food allergies in children are cows milk and egg, followed by soy, peanuts, tree nuts (such as walnuts, cashew, almond, brazil, etc.), fish and shellfish, and (gluten in) wheat. Thankfully most children will lose their allergy by 3 – 5 years of age. However allergies to peanuts, tree nuts and fish may be permanent.

Recent studies have found that up to 40 – 50% of eczema cases in young children are triggered by a food allergy (source: Allergy New Zealand). Typically it is most commonly due to dairy and egg.

There is no evidence that delaying the introduction of solid foods for longer than 4-6 months of age reduces the risk of food allergy, eczema or other allergic diseases. – See more at: http://www.allergy.org.au/patients/food-allergy/faqs?highlight=WyJndWlkZWxpbmVzIiwiZm9yIiwiZ3VpZGVsaW5lcyBmb3IiXQ==#sthash.dr44oMAr.dpu

What are the symptoms of a food allergy?

An allergy occurs when a person’s immune system reacts to substances in the environment that normally do not bother most people. These substances are known as allergens and can be found in house dust mites, pets, pollen, moulds and food.

Where and how the allergy symptoms present can be different for each person:

  Skin:

eczema, dermatitis, hives

  Lungs:

asthma

  Nose/eyes:

hayfever, runny nose, watery eyes

  Gut:

diarrhoea, vomiting, abdominal pain and bloating,colic, reflux

  Immune:

low blood pressure, rapid and weak pulse, shortness of breath

Are food allergies on the increase?

OK, so we hear this all the time right:

Back in my day you never heard of kids with peanut allergies, let alone all this gluten intolerance!

There’s some truth to this of course. The diagnosis of food allergies and intolerances has increased, so it makes sense that we hear about it now more than we used to. But, the fact remains that food allergies are on the increase. And not just here in New Zealand, but all round the world. One useful way of measuring the increase is to measure hospital admissions¬†of food-related allergic reactions. This graph shows the increase in Australia from 1993-2005:

Australia food allergy

Diagnosis of a food allergy

Allergy testing will help identify what trigger is causing the allergic reaction. If a food allergy is diagnosed then removal of that food from the diet is important.

Scientifically recognised methods for allergy testing include:

  • Skin prick
  • RAST test – a blood test which measures the allergic immune response to certain foods
  • Skin patch test

Methods which do not have any scientific evidence to support them include kinesiology (muscle testing), electrodermal testing, reflexology and hair testing. These methods can lead to a correct diagnosis. Allergy NZ has more information on allergy specialists in New Zealand

Reducing the risk of allergies for your baby

Regardless of whether you have a history of allergies in the family (on either side of the family) it is recommended that you:

  • Continue with your regular diet while pregnant, not avoiding any one particular food unless it will affect you personally.
  • If possible, your baby should be exclusively breast fed until six month of age.
  • Delay the introduction of solids, if possible, until six months of age.
  • After six months of age, do not delay the introduction of perceived ‘high risk foods’ to your child – there is no evidence that doing so will reduce their risk. However, if you suspect a particular severe allergic reaction may occur in your child due to family history or similar, then seek medical advice before the introduction of that food – for further information¬†see this site.

Dealing with anaphylactic shock

Anaphylactic shock is a life-threatening condition that can be brought on by some food allergies. Peanuts, some tree nuts, fish, shellfish and milk are some of the more common foods that can trigger this potentially fatal condition. The symptoms of anaphylaxis include:

  • Skin reactions, including itching and flushed or pale skin
  • Very low blood pressure
  • A swollen tongue or throat, this can cause¬†difficulty breathing
  • A weak and rapid pulse
  • Nausea or vomiting
  • Dizziness or fainting

For more information on the signs and symptoms of anaphylactic shock, see this article.

Food intolerance

Food intolerance is different to a food allergy as it does not involve the immune system. A person may still react to a food without being allergic to it. However with food allergies it is crucial to avoid all traces of the food which causes the allergy; in contrast a food intolerance does not always need strict avoidance. A person with a food intolerance may find they can tolerate small amounts of the food in the diet before they get a reaction to it.

What to do if you suspect a food allergy

Discuss this with your doctor and arrange to have appropriate tests carried out to confirm the allergy. If the tests are negative it is also important to consider the history of symptoms and it may still be necessary to eliminate the suspected trigger.

If a food allergy is diagnosed

It is important that you get advice on how to manage your diet to ensure it still meets nutritional requirements. This is especially true if food allergies have been diagnosed in a baby or young child ‚Äď it is vital to ensure their diet is adequate to allow for normal growth and development.

A dietitian experienced in dealing with food allergies will be able to provide you with suitable advice. A dietitian will be able to

  • Assess the diet for nutritional adequacy
  • Advise what foods are safe to eat
  • Teach you how to read food labels

To find a dietitian in your area consult the yellow pages, ring the local hospital or visit the New Zealand Dietitians website for a list of private practice dietitians in your area ‚Äď www.dietitians.org.nz

Useful websites and articles

Allergy New Zealand is a volunteer organisation set up to support people who live with allergies. Contact them on www.allergy.org.nz

Allergy Support New Zealand: https://www.facebook.com/groups/allergysupportnz/

ASCIA is the peak professional body of clinical immunology and allergy in Australia and New Zealand –¬†http://www.allergy.org.au/

Hopefully you’re now much more¬†informed on food allergy symptoms and diagnosis. You may also want to check out our article on Travelling with children who have food allergies. And check out our great nut-free muesli bar recipe, great for taking to schools with a nut-free environment.

Fiona Boyle

Fiona Boyle is a registered dietitian and nutritionist. She runs a private practice and gives nutrition advice to individuals and families to help meet their health needs and personal goals.

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