With the alarming rise in diagnosed allergies, there is a growing interest in the subject and most people either have or know someone who has a food allergy. So why are allergies increasing? Dietitian Angela Phillips explains.
With new research, there are a few theories around why allergies are on the rise. It could be due to the changes in the bacteria we have in our gut, a result of reduced vitamin D (which is the vitamin we mostly obtain through sunlight exposure), our increased hygiene practices, or it could be related to delayed introduction of solids. Most probably, it is due to a combination of all these and other factors. Hopefully over time, further research in this area will provide us with answers. Whilst children who have a family history of allergies are at an increased risk of developing an allergy, anybody, at any age can develop an allergy.
A food allergy is an abnormal immune response to ingested food. Allergies are often confused with food intolerance, so it is important to work with health professionals to distinguish between the two.
An allergy may cause symptoms such as:
- Breathing problems
- Gastrointestinal symptoms
- Eczema or rash
For some, these symptoms are mild and easily managed; but for others, it is hugely stressful and can result in many hospital admissions, sleepless nights, significant costs and, for some adults, the inability to continue to work.
Any foods can cause a reaction, but 90% of food allergies are caused by:
- Tree nuts
- Cows milk
Allergies are related to our immune system, with many sufferers being genetically predisposed to allergy. The question most frequently asked of a dietitian by the sufferer is “What can we do to help reduce the chance of developing an allergy?”
Previously, it was recommended that the risk of food allergy could be reduced by avoiding common foods that may trigger allergic reactions (known as allergens) such as nuts, egg, milk, soy, fish and wheat. However, based on more recent research, this does not appear to be the case. In fact, some studies show this may even increase the risk of developing food allergies.
A recently published article in the New England Journal of Medicine followed 600 children who were high-risk for peanut allergy, comparing children who consumed peanuts from an early age with children who were not introduced until age 5. Results showed that 17% of those who avoided peanuts to age 5 developed allergies versus 3% in the group who regularly consumed the peanuts.
Previously, it had been recommended that common foods which trigger allergic reactions such as nuts, egg, milk, soy, fish and wheat should be avoided during pregnancy to reduce the risk of the infant developing an allergy. Research is now showing this is not the case and if the mother does not personally have allergies, they should eat these foods during pregnancy. It is not yet confirmed if this will lower the risk of the baby developing a food allergy, but the latest evidence does not support avoidance.
Probiotics are helpful bacteria found in foods such as yoghurt or fermented foods. There is growing evidence that consumption of probiotics during pregnancy, breastfeeding and early infant life may help reduce the risk of eczema.
A New Zealand study published by the Clinical and Experimental Allergy journal reported that use of a maternal probiotic during pregnancy, breastfeeding and an infant probiotic for the first 2 years of life, halved the cumulative prevalence of eczema by age 2.
Women who are breastfeeding should continue to eat all foods, unless their baby has been diagnosed with an allergy. If a baby is diagnosed with a food allergy or has a suspected food allergy, under the guidance of her doctor, it is recommended the mother exclude this food from her diet for a period of time. Most women will be able to reintroduce the food back into their diet with no ill effect, as only small amounts of the allergen will transfer into their breast milk and this will often not be enough to trigger an allergic reaction. There is extensive evidence to show that breastfeeding, while introducing solids, will reduce the risk of children developing allergies. If the baby requires supplementary feeding, it is still beneficial to continue some breastfeeding alongside this. Therefore, if it is possible to continue breastfeeding, then it is ideal to do so.
Until recently, the recommendation for those with a family history of allergies was to delay introducing high-risk food allergens until at least 1 year of age. Based on the latest research, the recommendation now is to introduce these no earlier than 4 months, and preferably between 4-6 months, provided your baby is showing developmental signs that they are ready for solids. Foods should be added in any order, with a 2-3 day delay between the new foods to allow time to observe any effects. Once a food has been successfully introduced, regular consumption is ideal. A food allergy should be confirmed with support from your doctor, and if there is a confirmed allergy, then this food needs to be avoided. As most children will grow out of their food allergies, at some point in time your doctor or immunologist will support you with the re-trialling of that allergen to test the reaction.
As always, more research needs to be done in this very important area, and recommendations will continue to evolve. So, to reiterate, based on current evidence, delayed introduction of foods is not recommended. Introducing solids at around 4-6 months is recommended, ideally combined with breastfeeding.
The information outlined is based on the recommendations from the Australasian Society of Clinical Immunology and Allergy (ASCIA) who provide guidelines based on the latest research: www.allergy.org.au
did you know?
When a food is heated to high temperatures, it can reduce the risk of it triggering an allergic reaction, e.g. UHT milk vs fresh milk, commercially cooked egg vs raw egg. Exposure to heat-treated foods on a regular basis may even help improve tolerance in those with a food allergy. If your child has been diagnosed with an allergy, it is important to discuss the option of trialling heat treated foods with your doctor before undergoing the trial.
*Angela Phillips is a Dietitian specialising in paediatrics, food intolerances and weight management. Her practice, FoodSavvy, is based in Wellington and Nelson.