Children whose mothers had a low intake of vitamin E during pregnancy are more likely to develop wheezing and asthma by age five.
This research appears in the first issue for September 2006 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
Graham Devereux, M.D., Ph.D., of the Department of Environmental and Occupational Medicine at the University of Aberdeen in the United Kingdom, and seven associates assessed maternal nutrient and respiratory status in 1,253 mothers and children during a five-year period.
According to the authors, children born to mothers from the lowest quintile of vitamin E intake were over five times more likely to manifest early persistent asthma than children whose mothers were in the highest quintile.
"Our findings 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," said Dr. Devereux. "Lung function was associated with early vitamin E exposure independent of atopy, whereas allergic airway inflammation was associated with vitamin E exposure in later pregnancy."
However, the researchers also noted that the airways are fully developed by 16 weeks after conception and, consequently, vitamin E exposure in early pregnancy may be more likely to influence airway function than exposure later in pregnancy.
"The present study suggests that children's own nutrient intake at the age of five does not modify the associations between maternal nutrient intake and respiratory outcomes in the children," said Dr. Devereux.
The study cited vegetable oils (sunflower, rapeseed and corn), margarine, wheat germ, nuts and sunflower seeds as major food sources of vitamin E for mothers in the U.K.
In a prior report on this group of children, the researchers found that two-year-olds whose mothers' vitamin E intake during pregnancy had been relatively low were more likely to wheeze even when they had no cold.
For the previous study, the investigators recruited 2,000 pregnant women at 12 months gestation who were attending area antenatal clinics between 1997 and 1999. Plasma antioxidant concentrations were measured in 1,856 mothers at 12 weeks gestation. In addition, symptom questionnaire data was later obtained for 1,253 children. From that group, 478 children were able to provide a lung function test measurement.
In light of the new findings, the authors concluded that the relationship shown between mothers' vitamin E intake during pregnancy and the respiratory outcomes of their children were likely "underestimates of the true association."
"The results of the present study suggest that dietary modification or supplementation during pregnancy to reduce the likelihood of childhood asthma warrants further investigation," said Dr. Devereux.
The researchers added that vitamin E supplementation in adults with established asthma has not been shown to be of clinical benefit.