The findings suggest poor eating habits, and the dearth of vitamins that result, may help explain the rising number of children diagnosed with asthma since the 1980s, researchers said. About 20 million Americans have the chronic lung condition that inflames airways, making breathing difficult, according to the U.S. Centers for Disease Control and Prevention.
Women getting the least vitamin E were 5 times more likely to have children with persistent asthma at age five compared with women getting the highest levels, the study found. Children whose mothers got little of the antioxidant vitamin were also three times more likely to suffer from wheezing, a hallmark symptom of the potentially fatal breathing disorder.
``We're eating fewer vegetables than we used to,'' said lead researcher Graham Devereux, a pulmonologist from the University of Aberdeen in the UK. ``The decreasing intake of vitamin E during the past 50 years may account for some of the increase in asthma and may offer a way of trying to prevent asthma in the future,'' he said.
Results of the study, involving more than 1,200 women and their children, appear in the September edition of the American Journal of Respiratory and Critical Care Medicine. The researchers also found zinc consumption during pregnancy reduced active asthma, while the children's diet had no impact.
The findings aren't definitive and don't mean pregnant women should start taking vitamin E supplements, Devereux said in a telephone interview yesterday. Instead, they should be eating a healthy, balanced diet, he said.
Vitamin E is found at high levels in corn, nuts, leafy green vegetables, asparagus, vegetable oils and margarine. It is an antioxidant, thought to protect the body from harmful byproducts that develop during the metabolism of oxygen. The byproducts, known as free radicals, damage DNA and are thought to play a role in everything from aging to cancer.
Recent studies have yielded mixed results about the benefits of vitamin E supplements, however. High amounts of it can be harmful, and several studies failed to show it prevents cancer and heart disease. Other work suggests it may help ease symptoms of Alzheimer's disease.
Timing may be the key to vitamin E's benefit for children, Devereux said. The airways are fully developed by the time the fetus is 16 weeks old, and early intake of the vitamin may boost lung function, he said. The study found later consumption of the vitamin was linked to less allergic inflammation in the airways, he said.