Can’t eat, won’t eat?

How does having an aversion to a food differ from an allergy?

If something you eat makes you sick, you shrink from eating it again. Omnivorous animals like us show this avoidance reaction strongly. It evolves from two pressures: it’s good to try small amounts of new stuff when regular foods are in short supply, but if they harbour toxins, a second dose is a bad idea. Some people with a particular aversion can convince themselves they are allergic to this food and will vomit if given it. This reaction is psychological.

A true allergy is a reaction of the immune system. A strong allergic reaction, known as anaphylaxis, can involve a dangerous drop in blood pressure and difficulty breathing.

Food allergies develop in 6–8 per cent of children and appear to have increased in number in recent decades. They can be quite short-lived. Severe food allergies and deaths, however, are rare and have remained constant. There are around ten deaths from food allergies in England and Wales each year.

Some food allergies can be controlled by gradual exposure to small amounts of the offending food. In a carefully monitored study, researchers in Cambridge showed that sensitivity to peanuts could be reduced by feeding children increasing daily doses of peanut flour mixed into yoghurt. Following a three-year trial, the study had positive results, with the amount of peanut that could be tolerated by the children and teenagers on the trial increasing 1,000-fold. Subsequent studies have confirmed that this technique – called oral immunotherapy – is both a safe and effective way of treating peanut sensitivity in children, working in about 80 per cent of cases. 

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About this resource

This resource was first published in ‘Food and Diet’ in June 2011 and reviewed and updated in August 2016.

Microbiology, Psychology, Immunology, Health, infection and disease
Food and Diet
Education levels:
16–19, Continuing professional development