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Allergies and intolerances to food

Learn about the causes of allergies, the symptoms and how to avoid the foods your body cannot tolerate.

Food allergies and intolerances affect many people across all ages.

The detailed information below is also available in a free printed booklet called “Eating safely when you have food allergies”. To request a copy please call us on 0800 693 721 (0800 NZFSA1).

Food allergies – what they are and how they can affect you

Food allergy is a reaction to a food protein. The most common proteins (allergens) that trigger reactions are those found in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

The reaction is usually immediate – from a few seconds to two hours after you eat. However, in some types of food allergy, reactions are delayed. Allergic reactions vary and range from mild, such as a skin rash, to a fast, life-threatening reaction (anaphylaxis).

People with food allergies develop symptoms when eating foods that are part of most people’s healthy diet. Even small amounts of the offending food can cause serious reactions in susceptible individuals.

Food allergy is relatively common in children, but many children grow out of their allergies by adulthood. Food allergy affects up to 4% of children and up to 2% of adults. The tendency to allergy usually runs in families. The only way for allergic individuals to manage a food allergy is to avoid eating the food that causes it.

Symptoms of food allergy

The symptoms of food allergy range from mild discomfort to severe or life-threatening reactions requiring immediate medical attention. Symptoms include:

• Skin: hives, eczema, swelling, itching

• Respiratory: sneezing, asthma, difficulty breathing, cough

• Gastrointestinal: swelling and itching of the lips and mouth, vomiting, reflux, colic, diarrhoea, cramps, constipation

• Circulation: low blood pressure, dizziness, anaphylactic shock.

While around 160 foods can cause food allergies, there are eight, which are responsible for 90% of allergic reactions to foods. These are egg, milk, peanut, soy, fish, seafood, wheat, and tree nuts.

A food that causes an allergy is called an allergen. Allergens will affect a food-allergic person every time they eat it. For some people, only a tiny trace can trigger a reaction.

How allergies are identified

Your doctor or specialist will want your reaction history and will probably do a physical examination. There are also tests to help identify a food allergy.

During a skin prick test, small drops of the potential allergens are placed on your arm (or back for a small child). A tiny prick is then made in the skin so the allergens come into contact with tissue. A red and raised area will develop around the drop you are allergic to. Skin prick tests do not work if you are taking anti-histamines or using steroid creams. You will need to stop these several days before the test. Skin prick tests are not suitable if you have severe eczema, a severe peanut allergy (if suspected) or for distressed infants.

Another option is radioallergosorbent testing (RAST). This blood test checks for reaction to the eight major food allergens. You can have this test done while using antihistamines and steroid creams. There is also no risk of severe allergic reaction as your blood is taken away and analysed. Note though that a positive test result does not always mean an allergy.

If you, or your child, are diagnosed with a food allergy you need to avoid all sources of that food. Research suggests children have a better chance of growing out of a food allergy if they completely avoid the food. To find out whether you are still allergic or have grown out of an allergy, you can be re-tested.

In cases where the allergy is severe, you might need to wear a Medic Alert bracelet and carry special medication such as antihistamines or an auto-injector such as an Epi-Pen®. You should discuss this with your doctor.

Egg and milk allergies are the most common food allergies among infants but are often outgrown. Shellfish allergy is more common among adults than children. Peanut allergy is equally common among children and adults. When eliminating food groups from your diet, the supervision of a dietician is highly recommended.

The Ministry of Health has a range of publications about nutrition. Contact your doctor or local Public Health Unit (look in the White Pages under ‘Public Health’) or click on the link below.

Ministry of Health publications on food and nutrition [Ministry of Health]

The eight most common food allergens

These eight allergens are responsible for up to 90% of all allergic reactions.

Cow’s milk and cow’s milk products

There are many alternatives to cow’s milk for those who are allergic. However many processed products – such as bread and baked products, confectionary, pickles and manufactured meat products – contain milk products.

What to avoid:

• milk, yoghurt, cheese, butter, cream, buttermilk

• butter oil, butter fat, ghee

• calcium caseinate, casein, caseinate, sodium caseinate

• demineralised whey powder

• lactalbumin, lactoglobulin, lactose (milk sugar)

• rennet

• milk powder, milk protein, milk solids, non-fat milk, non-fat milk solids

• skim milk, skim milk powder

• sweet whey powder, whey, whey protein concentrate, whey solids.

Watch points:

• For adults, replace milk with a calcium-enriched alternative such as soy or rice milk. Note that some calcium-enriched alternative do not contain vitamin B1 which may be a problem for vegans

• Rice milk is not suitable as a sole milk replacement for children under five years old as it is low in protein and fat and contains fewer B vitamins

• For adults, oat and almond milk may also be used although these may not be calcium-enriched

• Goat and sheep milk should be avoided because it is likely to cause allergic reactions in people who are also allergic to cow’s milk

• For infants, breast milk is the best source of nutrition. Once weaned from breast milk, infants with milk allergy should use a low-allergen formula under the supervision of a paediatrician

• Coffee whitener may contain dairy products. Check that it is a non-dairy whitener before use.

Soybeans and soy products

Soy allergy might be increasing. More soy is being used in processed foods such as bread and baked products, cereals, confectionary and Asian foods.

What to avoid:

• soy protein, tofu, tempeh, soy beans, edamame, bean curd

• soy sauce, black bean sauce, miso soup

• soy or soya oil, salad or unspecified cooking oil

• soy flour

• soy lecithin or unspecified lecithin

• hydrolysed or textured vegetable protein (HVP and TVP)

• soy milk

• vegetable gum, vegetable starch.

Watch points:

• Many breads contain soy flour

• Asian foods in particular are likely to contain soy.

Eggs

Egg allergy can be severe and often occurs the first or second time an infant eats egg. Egg is also often found in processed foods such as baked products, noodles, soups and sauces.

What to avoid:

• egg white, egg yolk

• dried egg, powdered egg

• egg lecithin

• meringue

• mayonnaise

• custard powder

• albumin, ovalbumin, ovomucoid, globulin

• avidin, livetin, lysozyme.

Watch points:

Watch for products with glazes – they may not be listed ingredients

Safe egg substitutes are:

• gelatine

• golden syrup

• baking powder and vinegar

• yeast

• apricot jam

• water, oil and baking powder

• Orgran® or a similar egg replacer

• pureed apple

• cottage cheese

• Avoid all types of egg – chicken, duck, goose etc.

Fish and seafood

The fish commonly known to cause allergic reactions include cod, salmon, trout, herring, pike, hake, mackerel, haddock, shark, terakihi, hapuka, snapper, sole, flounder, halibut and tuna. Often the allergy may only be to one species of fish. Occasionally the allergy may not be to the fish itself but to a parasite present in fish.

Seafood is a broad term covering many different species. The common allergy-causing seafoods are shrimp, prawn, crab, crayfish, lobster, oyster, clam, scallop, scampi, paua, octopus, pipi, tuatua, mussel and squid. Despite not being seafood, snail also comes into this category.

Watch points

• Check for fish sauce (particularly in Asian dishes) and anchovies

• Cross-contamination is probably the main concern – even small amounts of fish could trigger a serious reaction. Ensure pans, utensils and crockery are well washed after use. Fish remnants can also remain on chopping boards - so keep a separate board just for fish. Cross-contamination can be an issue when dining in a restaurant, or eating food cooked in a deep fryer

• Even though surimi may not contain crab, it does contain fish

• Be aware of cross-contamination on in-store fish counters and in processing plants.

Peanuts

Peanuts are a common part of our diet. Unfortunately for those who have a peanut allergy, the effects can be very serious and even a tiny amount may cause a severe reaction.

What to avoid:

• groundnuts

• beer nuts

• monkey nuts

• peanut oil, arachis oil

• satay

• peanut flour

• mixed nuts.

Watch points

• Peanuts are a popular in-flight snack internationally. Check with your airline before flying as airborne peanut particles recycled in the air conditioning system could cause a reaction

• Any nut oils used in cooking or cosmetics should be avoided

• Those with peanut allergies may be more likely to have reactions to other nuts. This is even though peanuts are technically not a nut – they are a legume like peas. If your child is allergic to peanuts, delay giving them other nuts until at least three years old and include these in allergy tests. This includes Nutella® products

• Peanut butter presents the greatest hazard because it sticks to knives, benches, chopping boards, kitchen sponges and barbeques. Knives contaminate jams and spreads. Sticky fingers transfer it to door handles, toys, taps and school desks. In addition, well-meaning relatives can leave peanut butter kisses from lips, beards or moustaches

• Cross-contamination is also a common problem with peanuts themselves. Watch for pizza cutters, salad spoons; and where the nuts are going in ice cream shops. Loose nuts in bulk bins can end up in other containers. Check marinades and fruit breads in particular.

Tree nuts

Cashews are the most common cause of nut allergic reactions but it is best to avoid all tree nuts if you have an allergy to one of them.

What to avoid:

• Hazelnut (filberts)

• Almond (marzipan, amaretti, almondine)

• Walnut (butternut)

• Brazil nuts (cream nut, para nut)

• Pecans

• Pine nuts (pignoli, pinon nuts, Indian nuts or stone nuts)

• Pistachios

• Macadamia nuts (Australian or Queensland nuts)

• Chestnut (but water chestnut is not a nut)

• Cashew nuts.

Watch points

• Nut pastes such as Nutella® should be avoided

• Praline and nougat contain nuts

• Coconut is also a nut. There has been concern that coconut could also trigger allergy. In highly allergic children, allergy to coconut is a possibility, but it has not been observed to be a problem

• Sesame seeds could also pose a concern, and should be checked for signs of allergy. Sesame oil is in tahini and is an ingredient in hummus

• Watch for rogue nuts in bulk bins and avoid Christmas nut mixtures.

Wheat

A wheat allergy is an abnormal immune reaction to one of the thirty-five allergenic proteins in wheat. The major proteins are albumins, globulins, gliadins and glutenins. Often children grow out of a wheat allergy by age two.

What to avoid:

• wheat, wheat flour, wheat bran, breadcrumbs, wheat germ, wheat starch, semolina, couscous, bulgur, spelt, kamut, durum, dinkel and triticale

• bread, pasta, most breakfast cereals, baked goods such as cakes, biscuits, scones and muffins made with wheat flour

• hidden sources of wheat in sauces (most soy sauce), soups, dressings

• wheatgrass and wheatgerm

• check that corn flour and baking powder do not contain wheat starch

• spelt is sometimes promoted as being wheat-free – it is an ancient form of wheat and may still cause a reaction.

Watch points:

• Alternatives to wheat that you can eat include potato, oats, rye, rice, corn, sago/tapioca, buckwheat, legumes, millet and arrowroot

• Fibre may be low in a wheat-free diet, because many alternative flours are lower in fibre than wholemeal wheat varieties. Soy and buckwheat flours are higher in fibre than other alternatives. Increasing fruit and vegetables, using legumes such as beans and chickpeas, and including some whole grains such as millet, amaranth and buckwheat will ensure a good fibre intake. Add barley to soups and use brown rice as it is higher in fibre. A good high fibre wheat-free breakfast is homemade muesli with rolled oats, seeds, rice bran and fruit.

Other allergens affecting New Zealanders

Some of these are:

• seeds (sesame, sunflower, poppy)

• kiwifruit

• corn/maize

• lupin (lupin flour)

• mango

• legumes (chickpeas, beans, peas, lentils)

• spices (including mustard)

Sometimes environmental or contact allergies can have cross-reactions with food. This is because the allergy-causing protein is similar to a protein in the food.

One example is when people with a latex allergy sometimes react to banana, kiwifruit, chestnut and avocado. The protein in latex that causes the allergy is a natural protection the rubber plant produces to protect against insects. Banana, kiwifruit, avocado and chestnut plants also produce this or a similar protective protein.

Another example is people who are allergic to birch pollen may react to several different kinds of fruit, again because of similarities in proteins. Usually this causes reactions in the mouth and lips only (called oral allergy syndrome). You do not need to avoid these foods unless you know you react to them.

Finding allergens on food labels

Allergens that must be declared on food labels in New Zealand and Australia are:

• cereals containing gluten and their products (wheat, rye, barley, oats)

• crustacea and crustacean products (crab, prawn, crayfish)

• egg and egg products

• fish and fish products (including shellfish)

• milk and milk products

• peanut and soybean (including their products)

• added sulphite (above a certain level – there is more on this later in this guide)

• tree nuts and sesame seeds and their products.

There are three ways you might see allergens listed on labels:

Food labels should be checked each time before purchase or use as manufacturers do change their ingredients and processing aids from time to time.

You may have seen some labels with the statement “may contain traces of X” or “manufactured in a plant that also processes X” or even “manufactured on the same equipment as X”. Do not consume products with ‘may contain’ or similar precautionary statements if you have an allergy to that food. Manufacturers use this statement to cover a variety of situations. As companies continue to improve allergen management, these statements will increasingly represent more accurate risk levels. For individual advice please consult your health professional.

Food labels – what a label must show

The risk of allergens in food additives

People commonly ask whether food additives contain allergens. Because very small amounts of additives are used in foods, the amount of allergens is likely to be even smaller.

All food additives are listed on the food label, so you can avoid these if you are very sensitive. Check with the manufacturer if you are unsure of the source of an additive. Additives containing possible allergens are:

• E06 (tocopherol) – soy

• 322 (lecithin) – soy/egg

• Flavour – will list the allergen if it is present

• Wine – additives in the refining process of wine include milk, egg and fish. Evidence suggests there is only a very small risk that these are present in the final product.

Undeclared allergens – what to do if you discover one

You need to contact your local Health Protection Officer if you suspect:

• a food product containing an undeclared allergen to be the cause of a reaction

• a food item is not properly labelled

• you have been given the wrong information about food in a restaurant, which then led to a reaction.

Look in the White Pages under ‘Public Health’ to find the contact details for your local Health Protection Officer at your Public Health Service.

Foods with undeclared allergens might be recalled

Foods found to contain significant unlabelled allergens are recalled.

Recall notices are placed on our website, printed in major newspapers and broadcast on radio.

Foods recently recalled

Sign up for notification about food recalls

Planning a nutritionally balanced allergen-free diet

In most cases, it is still possible to have a nutritious diet while avoiding the foods you are allergic to. If you are avoiding whole food groups, it is essential you consult a dietician to ensure your diet is adequate. This is especially important for young children who need good nutrition for growth.

Calcium

Getting your calcium requirement may be tricky if you are avoiding milk and milk products.

Replacing cow’s milk with soy or rice milk that has calcium added is the easiest way to ensure your intake does not suffer. Note that rice milk is not suitable for children under the age of five.

Check the brand you buy is fortified – it will say ‘calcium’ on the nutrition panel on the packet. Adults need 1000-1300mg of calcium per day and children need 700-1300mg depending on their age. One glass of fortified soy or rice milk usually provides around 250mg. If your child will not drink any milk, look for alternatives although the choices become more limited.

Foods high in calcium include broccoli, tinned fish (with bones), oysters, soybeans and parsley. Foods with medium calcium content include tofu, baked beans, mussels, dates, almonds and bread. Foods sometimes fortified with calcium include orange juice and breakfast cereals. If you or your child have multiple food allergies it is likely that a calcium supplement will be necessary to meet requirements. Choose a supplement that does not contain calcium from shellfish sources if you have a seafood allergy.

Selenium

If you have multiple allergies, your diet may be low in selenium. This is because the main sources of selenium for New Zealanders include eggs, wheat, seafood and dairy products. Other good lower allergy sources of selenium include legumes (chickpeas, beans, lentils) and meat (especially liver and kidney).

Omega-3 fats

Fish is a good source of omega-3 fats, but other sources include canola oil, walnuts, linseed (also known as flaxseed), spinach and purslane.

Iron

Iron may be an issue for children with multiple food allergies, especially if they have an allergy to beef and lamb. For children with eczema, iron may be lost through shedding skin.

Good sources of iron include foods with added iron (Marmite®, Vegemite®, breakfast cereals, Milo®), beans (baked beans), tofu, dried apricots, raisins, nuts, whole grains, chickpeas, lentils and green leafy vegetables. Vitamin C improves the absorption of iron from plant foods so a glass of orange juice with a main meal is beneficial.

Tips for eating out and buying food when you have allergies

Eating a meal in a restaurant or café can be a harrowing experience if you have a food allergy. Here are some tips to make it easier and safer:

• Phone the restaurant in advance. Explain you have a food allergy and ask if they can cater for this. If so, go through the menu with them and work out something you could safely eat. If they are doubtful or unhelpful, try another restaurant

• When you arrive, talk to the wait staff and explain you have a serious allergy. If you have phoned ahead, say that you have already spoken with the chef and ask them to tell the chef you are here. If you have not phoned ahead, ask to speak with the chef or maitre d’

• Read menus carefully and clarify what is in foods if you are unsure

• Especially check dressings, sauces and desserts

• Double check for garnishes or extras when the meal arrives

• Take medication with you in case of a reaction

• Some restaurants may allow you to take in safe food for a child or you may be able to take safe bread to have before the meal

• Fried food may pose a particular risk as fryers often end up with bits from all sorts of foods including egg, wheat, fish, seafood and milk

• Check food displays in supermarkets and delicatessens for possible cross-contamination

• Ask staff whether food is prepared with clean equipment and with utensils kept separate for food containing the allergen, eg, chicken kebab kept away from peanut satay chicken.

How to minimise the risk of your baby having food allergies

Your baby is more likely to develop an allergy if you have a family history of food allergies. For example if both parents have an allergy or one parent and a sibling with allergy.

While you are pregnant and breastfeeding it is suggested that you avoid peanuts and peanut butter. Breastfeeding may be protective and, if you can, delay the introduction of solids until the baby is six months old. Avoid introducing cow’s milk, egg, and fish until age one, and peanuts, nuts and shellfish until age three.

Food intolerance – what this is and the main symptoms

Food intolerance covers all other food-related reactions, generally those that cannot be tested for. Food intolerance can affect anyone at any age and usually involves more than one food. Reactions can be delayed for several days and the reaction is usually dependent on the amount of food eaten. Symptoms of food intolerance include:

• Skin: hives, swelling, eczema

• Respiratory: asthma, sinusitis, nasal congestion

• Gastrointestinal: nausea, vomiting, diarrhoea, constipation, gas, abdominal pain

• Other: migraine, nerve pain, muscle pain, impairment of memory, depression

The types of food intolerance

Food intolerance can be divided into several groups.

Enzyme deficiency

If an enzyme in your digestive system is missing or not functioning correctly, it won’t be able to help digest the food it is associated with. This will cause digestive-related symptoms such as diarrhoea, bloating, wind and abdominal pain.

The most common enzyme deficiency is lactase, which causes lactose intolerance. Lactase digests the milk sugar lactose. Usually people can still tolerate small amounts of lactose-containing foods.

Other enzyme deficiencies are rare, but fructose, maltose and sucrose intolerances do sometimes occur. See your GP or dietician if you suspect lactose intolerance.

Allergy-like intolerances

There are some reactions to foods that commonly cause allergy, such as milk, wheat, egg and soy etc that are actually intolerances. These will not appear on allergy tests but can be tested for using atopy patch tests. This involves applying a paste of the suspected food to a patch of skin on your back and then monitoring for reactions over hours. These tests are only done by a specialist. Intolerances to foods are most easily diagnosed by an elimination diet under the supervision of a dietician.

Irritants

Some foods can be irritating to the digestive system, causing symptoms such as diarrhoea, wind, abdominal pain and bloating. Examples of irritants are caffeine, spices, garlic, onions, cabbage, dried fruit and sorbitol (found in sugar-free foods such as chewing gum).

Food chemical intolerance

The two main classes of chemicals that occur naturally in foods are salicylates and amines. These can affect or cause asthma, pruritis, hives, eczema and migraines.

Food toxins

Some foods contain natural toxins that can increase under certain conditions. Other foods produce toxins as they spoil. Some people may be very sensitive to these toxins and so be more likely to experience adverse effects.

• Spoiled fish produces histamine which can produce allergy-like reactions

• Green sprouting potatoes may cause stomach ache

• Kumara and parsnip damaged by insect attack or injury may cause illness. Cut out the damaged area and peel before cooking. Don’t eat it if it tastes bitter

• Dried beans and chickpeas contain toxins. These need to be soaked and cooked thoroughly to remove them

• Zucchini that tastes bitter or has a strong unpleasant smell may contain toxins from wild zucchini strains and should not be eaten

• Cassava, taro leaves and bamboo shoots must be properly prepared and cooked before eating.

Sulphites

Sulphites in food are required to be listed on food labels, although sulphite reactions are not due to an allergy, but intolerance.

Sulphites are preservatives used most commonly in wine and dried fruit. The additive numbers are 220 – 228. Sulphites will appear as one of these numbers in ingredients lists on food labels. Above a certain level, labels will say “contains added sulphites”.

Sulphites mainly cause asthma in sensitive people, but may also cause rashes, irritable bowel syndrome and headaches.

Where to go for further information about allergies and intolerances

Your Health Professional

• Your GP or local medical centre

• Allergy specialist or paediatrician – this requires a referral from your GP unless you are in Auckland or Christchurch where there are private allergy specialists

• Dietician – a hospital dietician requires a referral from your GP, or look for a private dietician.

Find a dietician in your area [New Zealand Dietetic Association]

Organisations and Websites

Allergy New Zealand – support, education and information for people with allergies [Allergy New Zealand]

Manufactured food database - foods free from common allergens [Manufactured Food Database]

Ministry of Health publications on food and nutrition [Ministry of Health]

Australasian Society of Clinical Immunology and Allergy (ASCIA) – promoting education and ethical medical practice [Australasian Society of Clinical Immunology and Allergy]

Anaphylaxis Australia – general advice about allergies [Anaphylaxis Australia]

Important disclaimer:

Every effort has been made to ensure this information is accurate. NZFSA does not accept any responsibility or liability whatsoever for any error of fact, omission, interpretation or opinion that may be present, however it may have occurred. This information does not replace or substitute for advice given by a medical professional. If you suspect you have a food allergy, you should see your doctor.