One in 10 Australian one-year-olds have a food allergy, but scientists still aren't sure why.
We all get told to prepare our homes for the arrival of our newborns, and that usually means a good spring-clean. But are we doing more harm than good by being too heavy-handed with disinfectants and not allowing our children to be exposed to any bacteria whatsoever?
Allergies are on the increase, and the most popular explanation for this is the "hygiene hypothesis" - that we're too clean.
The good news is that about half of children with allergies to foods such as milk and egg normally outgrow them by the ages of four to six
The scientific jury is still out, but I think there might be some truth to this. While I didn't want my children eating mud when they were younger, I'd rather they got a bit dirty than only being exposed to the disinfectant chemicals that are sometimes used so liberally around our homes.
An allergic reaction occurs when the immune system - wrongly perceiving a harmless substance, such as a particular food, as a threat - is triggered, producing a large amount of antibodies in the blood. This can cause or contribute to various conditions, such as eczema, hay fever and asthma. It's distinct from a food intolerance, where the body is temporarily incapable of digesting certain foods.
There's a close relationship between eczema and food allergies. Studies have shown that babies with severe eczema that started before six months of age are at particular risk of suffering a food allergy.
Last year, Melbourne's Murdoch Childrens Research Institute did a study of more than 5000 one-year-olds, finding that 10 per cent had a food allergy. The HealthNuts study found 9 per cent were allergic to egg, 3 per cent to peanut and 1 per cent to sesame.
The most common age for food allergies is under 18 months. But there's such a wide range of symptoms that it's often hard to be sure that food is to blame.
Reactions may occur immediately after eating a specific food, or can be delayed for hours or even days. I've seen first-hand how quickly symptoms can occur. While doing a live cooking demonstration on TV with young children, the presenter fed a child a fruit kebab I'd made. Within seconds, the child was violently ill. It was only afterwards that I found out about her allergy to kiwi fruit.
So is there anything parents can do to reduce the risk of a food allergy? Breastfeeding for at least four to six months seems to offer some protection, although high-risk foods, also known as allergens, may be transmitted through breast milk.
There's also some evidence that "sensitising" - that is, introducing a food to the child from an early age in order to avoid allergies - can be beneficial. In Israel, where most young children are given a peanut snack called Bamba, the instance of peanut allergies is extremely low. A 2008 study of 10,000 Jewish children in London and Tel Aviv, published in the Journal of Allergy and Clinical Immunology, found that the UK kids were almost 10 times as likely to have a peanut allergy as their peers in Israel.
The HealthNuts study in Melbourne also found it was safe to introduce cooked egg into an infant's diet from around four to six months of age (some guidelines had previously recommended that they not be given egg until after 10 months of age), and that introducing egg at this earlier age may even protect infants from egg allergy. More studies are being done to test this.
For babies with a family history of allergy, however, more caution is needed. New foods should be introduced one at a time for two to three days so any adverse reactions can be traced to the "trigger" food.
The good news is that about half of children with allergies to foods such as milk and egg normally outgrow them by the ages of four to six. However, allergies to nuts, fish and shellfish can be life-long; in such cases, the only way to remain healthy is to avoid the problem foods altogether.
I'm often asked about food substitutes for common allergens. For dairy products, I would try soya milk, rice milk, coconut milk and non-dairy ice-cream, which can be made with soya or tofu. For those with a gluten allergy, use wheat-free or gluten-free flour instead of plain flour.
For eggs, use commercial egg replacers or xanthan gum to bind foods together, or try tofu to create an "eggy" texture. It can be harder to bake cakes without eggs, but there are many delicious flapjack recipes that don't contain eggs and satisfy sweet cravings.
Annabel Karmel's egg-free sunflower seed and raisin cookies
75g brown sugar
1 tsp vanilla essence
40g sunflower seeds
50g plain flour
75g porridge oats
¼ tsp bicarbonate of soda
1/2 tsp salt
Preheat oven to 180°C. Cream butter and sugar until light and fluffy. Stir in all remaining ingredients until combined. Shape into walnut-sized balls and flatten slightly by pressing down with your hand. Place in oven for 15 minutes or until golden. Makes 14 biscuits.
From New Complete Baby and Toddler Meal Planner by Annabel Karmel; go to annabelkarmel.com for more.
This article first appeared in Sunday Life.