Preventing a food allergy

Is there anything that can prevent the onset of food allergies in adulthood? Not that anyone knows of. A number of studies do suggest that fibre-rich diets have a positive effect on the immune system – and while that's a long way off saying that lentils and oats will ward off food allergy, there are so many other benefits of fibre – like less heart disease, less diabetes, better weight management and possibly less bowel cancer, why wouldn't you ditch refined foods in favour of more legumes, whole grains, nuts, fruit and veg?

However, when it comes to helping prevent a food allergy in children there are some promising clues. Katie Allen calls them the "5 Ds".

1. Diet

There's no evidence that avoiding potentially allergenic foods like nuts or soy in pregnancy lowers the risk of children developing an allergy, according to Australia's peak allergy body, the Australasian Society of Clinical Immunology and Allergy (ASCIA) – and recent research from Murdoch Children's Research Institute found that high consumption of peanuts or tree nuts in pregnancy by non-allergic mothers reduced the risk of their babies having a nut allergy. The advice for feeding babies used to be to delay giving potentially allergenic foods like egg and peanut butter but some studies suggest that earlier exposure may be protective – researchers from King's College in London reported recently that children at high risk of peanut allergy were less likely to develop this allergy if peanut was introduced as soon as they began eating solids. ASCIA now recommends starting solids at four to six months while continuing to breastfeed.

2. Dry skin

Babies with eczema have a higher risk of food allergy but keeping skin moisturised may help. Moisturiser helps prevent the breakdown of the skin's protective barrier which in babies with eczema may trigger an immune response which may lead to food allergies.

3. Vitamin D

Despite living in a sunburnt country, many of us are low in vitamin D because of factors like sun protection – important for preventing melanoma – and more time spent indoors. Mothers who are low in vitamin D are more likely to have babies who are low in the vitamin too, says Allen, whose 2013 study found that babies with low levels of vitamin D at 12 months were three times more likely to have food allergy than those with normal vitamin D levels.

4. Dogs

Snuggling up to the family labrador is no guarantee of preventing food allergy – but some studies link having a dog or a cat in the house to less allergy.

5. Dirt

Our instincts might be to keep dirt and babies as far apart as possible, but there's a case for not being too squeaky clean. "This is often called the 'hygiene hypothesis' and is probably related to microbial diversity rather than from being 'too clean'. It's okay OK for babies to get down and dirty – just make sure hands are washed before handling food," says Allen, adding that one study found that when babies used pacifiers that had been dropped on the ground their risk of allergy was lower. "Having siblings also seems to be protective, possibly because siblings are sharing bugs. It's also thought that the high rate of antibiotic use has changed the microbial environment we live in."