Asking pregnant and breastfeeding women to avoid foods associated with allergies such as milk, eggs and nuts was not an effective strategy in preventing the development of allergy to those foods in their children, according to new research presented here at the annual meeting of the American Academy of Allergy, Asthma & Immunology.
Asking pregnant and breastfeeding women to avoid foods associated with allergies such as milk, eggs and nuts was not an effective strategy in preventing the development of allergy to those foods in their children, according to new research presented here at the annual meeting of the American Academy of Allergy, Asthma & Immunology. “Partial food avoidance strategies are not effective to preventing sensitization,” lead author Dr. Greg K. Appelt, of the Pediatric Allergy and Clinical Immunology Department at the University of Manitoba, told attendees at the meeting. Previous evidence of avoiding certain foods to prevent allergy have been mixed, he noted, with some studies finding decreases in dermatitis at one year. Other studies have found a decrease in allergy one year, but no difference at age seven. Appelt’s group conducted a study that enrolled mothers from the Canadian Asthma and Allergy Primary Prevention study. The children were considered high risk, defined as having either one first-degree relative with asthma or two first-degree relatives with IgE-mediated allergic disease. The researchers counseled the mothers to avoid peanuts, nuts, fish, and decrease milk and egg consumption in the third trimester and during the first year of breastfeeding. The women were also asked to delay the introduction of solids for six months and only introduce milk after one year, eggs after two years and nuts after three years. The researchers had parents fill out a food questionnaire before birth, and at 2 weeks, and then at 2, 4, 8, 12 and 24 months. At one, two, and seven years old, the child was given a skin test for sensitization to milk, egg, nut, soy and wheat. Data were collected from 545 families–251 randomly assigned to the intervention group and 246 were assigned to the “control” group in which no allergy avoidance measures were taken The researchers found that at one year of age, there was no statistically significant difference between the groups. For example, about 4 percent of children in each group were allergic to milk. As many as 20 percent of the children in the intervention group and 14 percent of the control children were allergic to egg, but the differences were not significant. At two years of age, there was a significant difference between the two groups in allergy to eggs, with 12 percent of the children in the intervention group allergic to eggs but only 6 percent of controls. Four percent in the intervention group were allergic to milk, compared with only 1 percent of the control group. About 9 percent of both groups were allergic to nuts at this age. By age seven, only about 1 percent were sensitive to milk, and 1 percent to 4 percent were sensitive to eggs. At that age, 11 percent of the intervention group and 7 percent of the control group were sensitive to nuts. “Overall, sensitization declined from ages one to seven,” Appelt said. At one year of age, 102 children showed sensitization, while at age seven, only 47 did so. “Children with a strong family history of asthma sensitize to common foods, but this wanes over time (for) milk and eggs,” he saidThe researchers concluded that partial food avoidance strategies in the third trimester and during breastfeeding were not effective in preventing sensitization to food among these high-risk children. On the contrary, the strategies seemed to worsen the outcome, for unknown reasons. “We have concerns that these avoidances may enhance sensitization to foods in high-risk children,” Appelt said. These findings contradict the current recommendation by medical groups for mothers to limit their children’s contact with these foods if their children are at risk for developing allergies, noted Dr. Wesley Burks, a professor of pediatrics at Duke University in Chapel Hill, North Carolina. “To not find that is surprising,” Burks said. However, he added, the data set was relatively small. “It’s a relatively small number of patients to make any conclusions.”(Source: Reuters Health, March 2004)