Researchers in Britain believe that children whose mothers had a low intake of vitamin E during pregnancy are more likely to develop wheezing and asthma by age five.
The researchers from the University of Aberdeen in Scotland carried out a study of 1,253 mothers and children during a five-year period in order to establish if there was a link between vitamin E intake during pregnancy and children developing asthma.
At the start of the pregnancy the women had blood tests and were asked to fill out questionnaires which tracked their food intake at various stages of the pregnancy.
The researchers then looked at how many of their children went on to be diagnosed with asthma.
The women were divided into five groups according to their vitamin E intake and a comparison was then done.
The researchers found that the women with the lowest vitamin E intake, between 3mg and 6mg per day, were five times more likely to have children with asthma than women in the group that had the most vitamin E.
Graham Devereux, M.D., Ph.D., of the Department of Environmental and Occupational Medicine at the University says they knew from animal studies that vitamin E influences respiratory development and they suspected the same was true for humans.
Devereux says the children born to mothers with the lowest intake of vitamin E were over five times more likely to develop asthma than children whose mothers had the highest intake.
He says the research suggest that vitamin E has a dual effect on lung function and airway inflammation and that the effects could change at differing periods of prenatal and early life.
The researchers say that as the airways are fully developed by 16 weeks after conception, vitamin E exposure in early pregnancy may be more likely to influence airway function than exposure later in pregnancy.
Dr. Devereux says that children's own intake of vitamin E at the age of five did not appear to change the situation but he does caution pregnant women not to attempt to boost their vitamin E levels during pregnancy by taking supplements because there are concerns over high intakes of the vitamin.
Major food sources of vitamin E for mothers are vegetable oils such as sunflower, rapeseed and corn, margarine, wheat germ, nuts and sunflower seeds.
The authors believe the relationship shown in the study between mothers' vitamin E intake during pregnancy and the respiratory outcomes of their children were possibly "underestimates" of the true picture and say further investigation is warranted.
The researchers also say that vitamin E supplementation in adults with established asthma has not been shown to be of clinical benefit.
The study appears in the American Journal of Respiratory and Critical Care Medicine published by the American Thoracic Society.