Healthnotes Newswire (January 25, 2007)—Allergic conditions like asthma, eczema, and hay fever (allergic rhinitis) are on the rise. In the United States and the European Union particularly, these types of allergies, known as “atopic” diseases, are seen more and more in children. Environmental and diet changes are among the prime suspects for this rise. In particular, some researchers think that the increased use of margarine and vegetable oils, combined with decreased consumption of oily fish rich in omega-3 fatty acids, may also promote allergies.

“It seems possible that it is mainly prenatal or very early life environmental factors that influence the development of allergic diseases,” wrote Dr. Mauro Calvani of the Department of Pediatrics at Rome’s San Camillo de Lellis Hospital. “The changing lifestyle in Western countries may explain the dramatic increase in the prevalence of atopic disease in recent years.”

Dr. Calvani and colleagues have published a new study that offers preliminary confirmation of these theories. They found that nonallergic pregnant women who ate fish two to three times per week or more were over a third less likely to have children with atopic sensitivities to food than were women who ate less fish. However, this protective effect was not found in the children of women with allergies.

The study reviewed nearly a thousand children who attended outpatient allergy clinics at six different hospitals throughout Rome. About 75% of the children were affected by atopic diseases (such as asthma, rhinitis, or eczema); the other 25% attended the clinics due to other symptoms that resembled those caused by allergies but which were not true allergies. A detailed questionnaire and skin-prick tests were used to determine allergic sensitivity. The diets and allergic status of the mothers were also noted.

Researchers also studied the relationship between fish, margarine, and butter in the mothers’ diets, and whether they had allergies. There were no significant differences in the amount of fish and butter eaten by allergic mothers and nonallergic mothers. However, the researchers found that women with allergies tended to eat more margarine than those with no allergies, a dietary habit that raised their own risk of allergies threefold. The amounts of butter or margarine eaten by mothers were not related to allergies in the children of either group.

The present study has limitations: It was retrospective, meaning that researchers looked back at data from existing questionnaires and medical records, and did not specifically interview or test these patients as part of their study. Larger, “prospective” studies (ones that watch for outcomes, such as the development of a disease, during the study period) are needed to confirm these preliminary observations.

“If the results of our work are confirmed by other well-designed research,” Dr. Calvani concluded, “it could be beneficial to advise mothers to increase fish intake during pregnancy.”

(Pediatr Allergy Immunol 2006;17:94–102)