In an eight-year study, children diagnosed with asthma or other respiratory symptoms such as dyspnoea or wheezing were significantly more likely to be born to mothers who ate nuts or nut products, such as peanut butter, every day of their pregnancy than women who only ate nuts occasionally.

It is believed children may be more prone to developing asthma if they were exposed to allergens from nuts in utero, claim the papers. But researchers say it is too early to advise women to avoid nuts during pregnancy.

What is the research?
The findings come from a Dutch birth cohort study that involved just under 4,000 pregnant women.

The women completed dietary questionnaires during pregnancy and their children were followed up at three months old and then annually from one to eight years.

A child was defined as having asthma symptoms if the parents reported at least one attack of wheeze, dyspnoea or prescription of inhalation steroids in the previous 12 months.

Complete data from 2,832 mother and child pairs showed that children whose mothers ate nut products every day during pregnancy had a 47 per cent increased risk of developing asthma.

There was also a 42 per cent increased risk of wheezing and a 58 per cent higher risk of dyspnoea in this group of children.

What do the researchers say?
Lead author Saskia Willers, from the University of Utrecht, said: 'The only consistent association between the maternal intake of the investigated food groups during pregnancy and childhood asthma symptoms until eight years of age was with nut products.

'However, it is a bit early to say that women should avoid nut consumption,' she added.

'It is important other studies replicate our findings before giving diet advice.'

What do other researchers say?
Dr John Heffner, former president of the American Thoracic Society, said: 'These findings emphasise the critical importance of additional investigations into the environmental exposures for both mother and child that underlie the pathogenesis of asthma.'

Leanne Male, assistant director of research at Asthma UK, said: 'With one child being admitted to hospital every 16 minutes with their asthma, it is vital for research to consistently identify which foods can help ward off asthma in children so that we can provide dietary advice to pregnant women.

'To do this, we need further studies like this one.'

emma.quigley@haymarket.com

Am J Respir Crit Care Med 2008;178:124-31.

Informing Patients

• Pregnant women eating nuts or nut products every day may increase their child's risk of developing asthma, but more research needs to be done.
• Wheezing and dyspnoea were more likely in children born to mothers who ate nuts or nut products every day during pregnancy.
• Women should continue to eat a healthy, balanced diet during pregnancy.
• Asthma is likely to result from genetic and environmental interactions.

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