Expert shares inside knowledge on allergies

Food allergies and intolerances are increasingly prevalent these days. Dietitian Jenny Douglas shares her inside knowledge.

Having a young child with food allergies or intolerances can be very worrying for parents. Sometimes it’s hard to know whether your child is reacting to food or is just unsettled due to something else, such as teething. In this article I’ll explain how to identify adverse food reactions in your baby, and what you can do to reduce the risk.

FOOD ALLERGY VS FOOD INTOLERANCE
Food allergy: this is an immune response (IgE) to a certain type of food. This kind of reaction normally occurs within one to four hours of ingesting the food and involves symptoms such as hives, breathing changes, a persistent cough, a hoarse voice, a rash and projectile vomiting. Food allergy occurs in around 11% of babies under 12 months, and occurs in around 4–8% of those aged around four to five years old.

Food intolerance (non-IgE): in infants this is more common than food allergy, and may occur over a period of 4–24 hours after your child ingests a food. This type of reaction does not involve the immune system, but often has some similar symptoms. In infants, symptoms are often unsettled and distressed crying, abdominal pain, bloating, diarrhoea and/or constipation. 

REFLUX
Reflux is very common in babies. It doesn’t usually need any dietary changes as most babies outgrow it, or it can be managed with minor changes to feeding with the help of breastfeeding support. Of the New Zealand children referred to a paediatrician for severe reflux in 2008, around 40% had an underlying cow’s milk protein intolerance. Discussing reflux with your GP, plunket nurse or a registered dietitian can be useful to help you decide whether excluding cow’s milk from your child’s diet would be beneficial before putting them on any anti-reflux medications.

HOW DO YOU TEST FOR FOOD ALLERGY AND FOOD INTOLERANCE?
Accurate testing for food allergy and food intolerance can be very challenging. Many companies offer food allergy testing services, such as hair testing, which often come up with long lists of foods to exclude. There is little to no evidence these tests are effective in identifying food allergy/intolerance.

With food allergy (IgE immune-mediated), a specialist or GP will determine whether your child has a food allergy based on their reactions to that food. After hearing your child’s history, your GP or specialist may order some food allergy tests, such as IgE serum bloods or skin-prick tests. These tests need to be used alongside medical history to make a diagnosis of food allergy.

For food intolerance (non-IgE ) there are no reliable tests. The best way to find out if your child has food intolerance is to talk over their symptoms with your GP or a registered dietitian, and together identify some foods that may need to be excluded to see if the symptoms are resolved. It’s very important to add this food back into the diet in order to show a negative reaction and help prove that it is a real food intolerance.

WHAT CAN I DO TO PREVENT MY BABY HAVING A FOOD ALLERGY?
Babies who are born to parents who already have food allergy, hay fever or asthma have increased risk of allergy; and babies who have a sibling with food allergy also have increased risk. However, this doesn’t mean your child will definitely get a food allergy and you do not need to exclude allergen foods during pregnancy, while breastfeeding or from your child’s diet, unless they react. 

Some ways you can help to reduce your baby’s risk are: 

⚪  During pregnancy, eat a fibre-rich diet including a variety of all foods, such as wholegrains, vegetables and fruit. 

⚪  During pregnancy have three serves per week of omega-3 from fatty fish, as this may have some protective effect for eczema.

⚪  Introduce solid foods into your child’s diet from around six months, but not before four months of age. Cow’s milk (yoghurt, cheese or milk in cooking), wheat (bread, Weetbix), cooked egg, smooth peanut butter, fish/seafood and soy (usually soy flour in bread) should be introduced from six months of age and before the age of 12 months to help reduce the risk of allergy. 

⚪  Breastfeed exclusively for the first six months of your baby’s life and continue breastfeeding while solids are introduced until your baby is two years old.

⚪  If you can, choose a vaginal birth as studies have shown babies born vaginally tend to have lower allergy rates than babies born via C-section.

⚪  Probiotics in the last trimester of pregnancy and for the first three months of life may reduce the rate of eczema.

⚪  There is no need to use hydrolysed formula if you cannot breastfeed as this has not shown to reduce allergy risk. 

IS ECZEMA A SIGN OF FOOD ALLERGY?
Eczema occurs in 15–20% of infants and children and causes dry and itchy skin over the body. Eczema increases the risk of food allergy, but it’s not always caused by food reactions. Moisturising affected skin regularly during the day is essential to keep eczema under control. Correct creaming often gives better outcomes than excluding foods from the diet; many children can end up on quite restricted diets, with large numbers of foods excluded, and nutrients important for skin health can be depleted. The Child and Youth Eczema Clinical Network has useful resources for parents about how to apply moisturiser, how to bath your child and how to manage skin flare-ups.

WHY ARE ALLERGIES SO PREVALENT NOW?
New Zealand and Australia have high rates of food allergy and food intolerance, but medical research has not yet managed to pinpoint one isolated reason for why the rates are so high.

Some theories are:

⚬  Previous avoidance and delay in the introduction of food allergens was incorrect advice as it increases the risk of food allergy. 

⚬  Overuse of antibiotics may have affected our gut microbiome to predispose us to allergy.

⚬  The Western diet is high in processed, nutritionally depleted foods which don’t support a healthy gut, which acts as a type of barrier to allergy. 

⚬  Children born in rural areas and those with pets have lower rates of food allergy than city kids, which may suggest we’re being too ‘clean’ with our children.

⚬  Children and adults are now carrying childhood diseases, such as asthma and food allergy, into their adult years and these adults are having children with an increased risk of allergy.

HOW DO I INTRODUCE ALLERGEN FOODS INTO MY CHILD'S DIET?
It’s important to introduce allergen foods (eg peanut, egg, wheat, milk, soy, fish and seafood) to your baby’s diet from the age of six months and before they’re 12 months. Note that it’s useful to introduce new allergen foods when your child is well, and to do it at the beginning of the day. Gently place a very small amount of the food inside their mouth. If there’s no reaction, try another small portion of food again around two hours later, and repeat these steps the next day with increased quantities. Test one allergen food every two to three days. It’s important that once you introduce allergen foods you continue to give them weekly to maintain the tolerance level. Foods that aren’t common allergens can be introduced at any time and don’t need to be introduced in this slow fashion. 

WHAT TO DO IF A CHILD HAS A REACTION TO FOOD
If your child has any difficulty breathing, becomes floppy or pale, has significant hives or you are very worried, then call an ambulance immediately. If your child has a mild reaction, for example crying, some diarrhoea or changes to their bowel habit, then write down what they’ve eaten and their reaction and discuss this with your GP, Plunket nurse or dietitian.

When a food group has been identified as being a trigger to your child’s symptoms, they’ll need to stop eating it. It’s important that you get support from a dietitian to find out how to identify these allergens in foods and what to substitute them with to ensure your child is getting enough calcium, calories, protein and other nutrients for growth. Your specialist can help you identify when your child may be ready to try the food again.

Your child’s caregivers will need to know your child has a ‘no sharing’ policy, and younger children with an allergy may need a one-to-one carer at mealtimes to ensure there’s no sharing of food, especially if they’re at a daycare centre. It’s highly unlikely that a child will react to a food by just being around others who are eating it – they usually need to actually ingest it for a reaction to occur. Allergy NZ has good guidelines on food allergy management in a childcare setting, find out more at allergy.org.nz.

HOW CAN I HELP MY CHILD?
Most children outgrow food allergy to cow’s milk, soy, wheat and egg by around four to five years of age. There have been some studies looking at whether probiotics may help reduce this time, but the results are not clear. Children with food allergy to nuts and fish are less likely to outgrow their allergy, and generally continue to have this food allergy into adulthood.

For food allergy (IgE ), it’s important to avoid the food allergen in your child’s diet. Your specialist may decide to carry out a ‘Supervised Food Challenge’ at a paediatric assessment unit at your local hospital when your child is around three to five years old. This involves giving your child a small amount of the food they’re allergic to with medical observation. If no reactions occur, your specialist may ask you to start adding small amounts of this food back into your child’s diet.

If your child has food intolerance (non-IgE) they may tolerate the food in baked form. For example, a child with cow’s milk intolerance may tolerate some milk in a baked muffin. This would need to be discussed with your GP, a specialist or a dietitian who will advise how to do this safely.

We know that a healthy diet plays an important role in producing a healthy microbiome in the gut. Encouraging your child to eat a variety of vegetables, fruits, wholegrain breads/cereals, nuts/seeds and lean proteins will help them keep a diverse colony of gut bacteria.

Children with food allergy and food intolerance are more likely to have fussy eating behaviours, however this can be due to adult behaviour when they’re eating. Many children will encounter adults taking their food away in a panic saying, ‘You can’t eat that’ which can make the child quite anxious about eating new foods. For adults, keeping calm at meals and in social settings is very important; if you see your child about to eat foods they shouldn’t, swiftly but calmly take the food away and distract them by saying something like, ‘Why don’t we try these grapes, they look delicious’. To help your child avoid fussy eating behaviour it’s important to educate them from the start about what foods are safe to eat and what foods are not. 

Food allergy and intolerance may seem scary to parents but the incidence is not actually as often as you think, and most children outgrow it. There’s no need to avoid foods unless your baby has a reaction. If your baby reacts to food it’s important that you see your GP and/or a specialist to get advice on what to do next. A registered dietitian plays an important role in guiding you through how to avoid allergen foods and how to substitute the food to ensure your child grows and thrives. 

Helpful resources:

⚬  If your baby reacts to a food, see your GP and/or a specialist for advice on what to do.

⚬  Allergy NZ has good guidelines on food allergy management on their website allergy.org.nz.

Jennifer Douglas is a registered dietitian who specialises in nutrition and food allergy and intolerances. She has more than 14 years’ experience working with families whom she sees in her Dunedin clinic or via Skype. She also holds baby and family feeding seminars in Dunedin or via virtual link to parenting groups. Find her at jumpstartnutrition.co.nz.