Children who don't eat their greens could be three time as likely to suffer from asthma, says a new report.

Doctors studied asthmatic and non-asthmatic children in Saudi Arabia where different communities can have very different diets.

The research, reported in the medical journal Thorax, found that children whose diets were relatively low in vegetables and vitamin E were around three times as likely to suffer a wheeze.

Family history of asthma and allergic tendencies were also linked with asthmatic children. Their diets were also found to be low in milk and certain minerals.

But family size, numbers of infections, level of affluence, and parental smoking, all of which are widely considered to be risk factors for asthma, were not associated with wheeze, the research showed.

As prosperity has increased in Saudi Arabia over the past 30 years, so has the tendency towards a Western diet, say the authors, led by Professor Anthony Seaton, of the University of Aberdeen.

Poor diet is likely to be an important risk factor for asthma and allergies and a change in diet may therefore largely explain the increase in prevalence of these conditions in developed countries, they conclude.