MONDAY, May 21, 2007 (HealthDay News) -- Filling up on apples and fish during pregnancy might protect your child from developing asthma and allergic diseases, a new study shows.
Researchers from the Netherlands and Scotland have found that eating apples throughout pregnancy may protect against wheezing and asthma in 5-year-old children, while fish consumption may lower the risk of eczema, an allergic skin condition. The findings were to be presented Sunday at the American Thoracic Society's International Conference in San Francisco.
"To our knowledge, we are one of the first studies evaluating the influence of maternal consumption of so many different foods and food groups during pregnancy on childhood asthma and allergic disease," said study author Saskia Willers, a doctoral student at Utrecht University in the Netherlands.
Previous studies in the same group of children, part of the SEATON birth cohort conducted at the University of Aberdeen in Scotland, found that maternal intake of vitamins E and D, and zinc during pregnancy may also lower the risk of asthma, wheezing and eczema. For this study, the researchers looked at how eating different foods, rather than individual nutrients, during pregnancy impacted these children.
The researchers studied 1,212 children born to women who had filled out food questionnaires 32 weeks into their pregnancy. When the children were 5, the mothers filled out another questionnaire about their child's respiratory symptoms and allergies, as well as a survey about their child's food consumption. The children were also given lung function and allergy tests.
The study found that children of women who ate more apples and fish during their pregnancy were less likely to develop asthma or allergic disease. Specifically, children of women who ate fish once or more a week were 43 percent less likely to have had eczema at age 5 than children of mothers who never ate fish. Those whose mothers ate more than four apples a week during pregnancy were 37 percent less likely to have ever wheezed, 46 percent less likely to have had asthma symptoms, and 53 percent less likely to have had doctor-confirmed asthma compared to children of mothers who ate one or no apples a week.
"We were quite surprised to see a protective effect of apples, because, to our knowledge, no other study had seen that before," said Willers. "For fish, there is an earlier study that found a protective effect of maternal fish intake during pregnancy on childhood asthma."
No protective effect was found against asthma or allergic diseases from many other foods, including vegetables, fruit juice, citrus or kiwi fruit, whole grain products, fat from dairy products or margarine or other low-fat spreads.
The study speculated that apples may be beneficial because they contain flavonoids, which have been associated with a reduced risk of asthma in other studies, while fish's protective effect may be due to their omega-3 fatty acids.
"The authors' explanations are plausible," said Dr. Carlos Camargo, an associate professor of medicine and epidemiology at Harvard Medical School. "It's curious, however, why only apples would be protective, since flavonoids are present in other foods. This will require further work. The first step, however, is to see if other investigators find the same associations in other birth cohorts."
Dr. Augusto A. Litonjua, an assistant professor at Harvard Medical School, said this study adds to the growing literature that prenatal factors, specifically maternal diet during pregnancy, can affect the development of wheezing illnesses, asthma and allergies in young children.
It's too early, though, to recommend how much fish and apples pregnant women should eat, Willers said. Rather, it's important for them to follow a healthy, balanced diet.
Connie Diekman, director of university nutrition at Washington University in St. Louis, added that pregnant women should be careful about not eating too much fish because of the potential mercury and other pollutants in fish.
"The study supports the health benefits of increased fruits, vegetables and fish, but pregnant women need to exercise caution with king mackerel, tilefish, shark and swordfish, and should limit albacore tuna to 6 ounces per week," she said.
Litonjua added that in addition to a healthy diet, pregnant women should also take prenatal vitamins with folic acid and abstain from smoking and drinking to maximize the health of their growing fetus, and subsequently their young child.
For more on allergies and asthma, visit the Asthma and Allergy Foundation of America.