Scientists fear the high saturated fat levels lower children’s immune systems.

A research project involving more than 50 countries found that teenagers who ate food such as burgers three times a week or more were 39% more likely to get severe asthma. Younger kids were 27% more at risk.

Both were also more prone to the eye condition rhinoconjunctivitis. However, three weekly portions of fruit and vegetables cut the risk by 14% in the younger group and 11% among the teens.

Researchers from New Zealand’s Auckland University looked at the diets of 181,000 children aged 6-7 and 319,000 aged 13-14.

The study also asked if they had allergy symptoms. The study authors said their results do not prove cause and effect.