91Èȱ¬

Scientists are to begin clinical trials to determine if eating more foods rich in vitamin E during pregnancy prevents childhood asthma.

Women will eat soups naturally high in the vitamin, which it is believed may promote lung growth in the developing foetus.

Children born with good lung function are less likely to develop asthma.

Details of the trial were outlined at the British Science Festival being held in Aberdeen.

Asthma is highly prevalent - in the UK, 10-15% of children and 5-10% of adults have been diagnosed with the disease.

The majority of children with asthma will carry the illness into adulthood.

The disease is managed by preventing and relieving the major symptoms - breathlessness, wheezing and coughing - using inhalers and, in extreme cases, with steroid tablets.

There has been a recent increase in the prevalence of asthma in children.

To try to understand why, a team of researchers from the University of Aberdeen established a cohort of approximately 2,000 women and measured the impact of diet on the incidence of asthma in children up to the age of five.

Prof Graham Deveraux, who led the study, said: "We were able to show, for the first time, that children born to mums with a lower vitamin E intake during pregnancy were more likely to develop asthma by the age of five and have poor lung function."

These early findings were then confirmed in studies carried out in Japan and the US.

The next challenge for the researchers was to show that altering nutrition during pregnancy could positively impact on a child's susceptibility to asthma.

Prof Deveraux considered that a trial using vitamin supplements lacked credibility - trials of vitamins to treat various conditions had so-often failed.

He said the key may be intake in food.

"People have never actually eaten vitamin E tablets; normally most people get their vitamin E from food.

"I wondered whether it might be the other nutrients that go with vitamin E in food that may be responsible for the effect. There may be interactions between vitamin E and the other nutrients.

"So, I was very keen to do a dietary intervention rather than a pill or a potion."

With the help of a team of dietitians, he performed a small study on pregnant women to see if he could manipulate their diet to increase their vitamin E intake up to the recommended levels and, he says, "it worked a treat".

But vitamin E was not the only thing that altered, as Prof Deveraux observed: "Lots of other things changed, like the fatty acids changed, the zinc changed, the selenium, the vitamin D - and all these are nutrients which we know have been associated during pregnancy with childhood asthma."

Whilst the results vindicated their overall approach, the dietary interventions were too complex and would not be readily accessible to a wide range of society. Also it was difficult to standardise and control.

To overcome these problems, the team approached a commercial soup manufacturer to develop a range of enhanced soups. Each one is naturally rich in vitamin E - and other potentially important minerals - and for each there is a similarly tasting "normal" soup that could be used for the control group of pregnant women.

By judicious tweaking of ingredients - for example, substituting normal tomatoes found in cream of tomato soup with their super-nutritious sun-dried counterparts - they were able to develop three new varieties of "super-soups".

The team now plan to test the soups in a small pilot study involving 50 women. They will be enrolled during early pregnancy and asked to eat either enriched or normal soup three times a week.

The study will show whether the new dietary intervention is well tolerated by the women and - by carrying out blood measurements - if it has the desired effect on vitamin intake.

They might also get an early indication that the approach could prevent asthma. "If we're really lucky we might show that the children [born to women] receiving vitamin E enhancement may actually have better lung function," Prof Deveraux commented.

The overall approach has support from both nutritionists and asthma experts.

Prof Maijaliisa Erkkola, from the University of Helsinki, told 91Èȱ¬ News: "Appropriate food-based strategies that could contribute to reducing low maternal intakes of vitamin E to prevent asthma in offspring and to improve health of children are welcome."

Whilst Prof Ian Hall, from the University of Nottingham and an expert on asthma, told us: "In general these studies [using diet supplement tablets] have been disappointing in that they have failed to show reductions in the risk of developing asthma in the treated subjects.

"The current study adopts a novel approach by using natural supplementation in soup rather than a tablet based approach: it will be interesting to see if this proves more successful".

If the pilot study is successful in its primary aim - increasing vitamin intake - then Prof Deveraux and his team plan to carry out a much larger trial in over 1,000 women.