Children who eat fast food three or more times a week have a higher chance of developing asthma, eczema, or hay fever, a New Zealand-led study has found.
Eating fresh fruit, in contrast, can act as a protective factor against these allergy-based conditions.
The study, published today in journal Thorax, surveyed more than 400,000 children from 51 countries. Over 26,000 of them were New Zealanders.
It found that teenagers who ate fast food three or more times a week had a 39 per cent increased risk of severe asthma, while primary school-aged children had a 27 per cent higher risk.
However, eating three or more servings of fruit a week could cut the chance of severe asthma, eczema, and hay fever by between 11 and 14 per cent across the age groups.
The University of Auckland's Professor Innes Asher, who led the study, said parents should sit up and take notice of the results.
"These results are quite concerning, because fast food outlets are on the rise," Prof Asher said.
"The bottom line is that people should be careful about the amount of fast food they eat."
Though the exact reason why consumption of fast food is linked to these conditions is unknown, Prof Asher cites factors such as high levels of trans- and saturated- fatty acids as possible contenders.
These fats are known to affect immunity, which could in turn lead to allergy-related conditions.
Eating fresh fruit provides protection against these conditions because they contain beneficial antioxidants, she said.
The study indicates an association between the factors, rather than establishing a causal link.
The research team is currently looking for funding for a future study, which would establish whether this link is present.
If causality is established, then "the findings have major public health significance owing to the rising consumption of fast foods globally," Prof Asher said.By Victoria Cotterell