Nut a problem

Exposing children to allergenic food at a very early age may help them avoid developing dietary intolerances that can be a lifetime scourge.

- Nicky Pellegrino

Food allergies have been on the rise in developed countries over the past few decades and rates of hospitalisation for food-related anaphylaxis have risen steeply to match. The root cause is believed to be improved hygiene practices, which have restricted our exposure to microbes in our environment. Those exposures, particularly in gestation and early life, are key to establishing the intestinal microbiota – the trillions of tiny organisms in our gut – and consequently programming the immune response and influencing our risk of developing an allergy.

“Obviously we needed to improve sanitation to stop diseases such as cholera and typhoid, but doing so has come with a drawback,” says Professor Mimi Tang, an expert in allergic and immune responses from Melbourne’s Murdoch Children’s Research Institute. “That drawback is the breadth of bacteria and other micro-organisms that we’re exposed to has shrunk.”

Changing diets probably play a part, too, with processed foods replacing microbiome-friendly fresh fruit, vegetables and fish oils. And there may be a relationship with UV exposure – the closer you live to the equator, the lower your likelihood of allergy problems.

In the 1990s, most guidelines recommended not feeding highly allergenic foods, such as peanuts, to children aged under three to protect them from developing an allergy. “The thinking was that the gut barrier is less mature in infants than adults,” explains Tang. “So, by not exposing young children to these allergenic foods we would avoid a negative response.”