Can Exclusive Breastfeeding Protect Certain Children From Food Allergy?

By Anne Harding

NEW YORK (Reuters Health) - Babies who are exclusively breastfed for at least four months may be at lower risk of developing food allergies at six years of age, according to a new report.

"Our results would at least support the benefits of exclusive breastfeeding, especially for four months," said lead author Dr. Stefano Luccioli of the Office of Food Additive Safety at the Food and Drug Administration in College Park, Maryland.

"There's certainly other benefits that have been reported, and there may also be a reduction in food allergies as well," he told Reuters Health.

Some past research has found that children exclusively breastfed for at least four months are at lower risk of developing allergic disease, but questions remain about the role of complementary food introduction and allergy risk.

To investigate, Dr. Luccioli and his colleagues surveyed women beginning in pregnancy and through their infant's first year of life, and surveyed them again when their child was six years old. The follow-up analysis included 1,363 children.

At six years of age, 97 children (6%) had physician-diagnosed food allergy, based on parent report. Seventy-eight of the children diagnosed at age six did not have reported food allergies at one year of age.

Dr. Luccioli and his team classified 823 of the children in the study as "high risk," based on whether they had a family history of food allergy or other allergy, or a history of eczema reported by age one. These children were nearly twice as likely to have probable food allergy at age six (adjusted odds ratio, 1.86), the researchers report in the September issue of Pediatrics.

Children whose mothers were more highly educated or came from higher income families were also more likely to have probable food allergy compared to their peers with a family income below 185 percent of the poverty level (aOR, 1.70).

Children who had been diagnosed with asthma before they were 12 months old had an aOR of 3.69 for total or newly diagnosed probable food allergy. Among the high-risk group, higher family income was the strongest predictor of food allergy risk (aOR 3.19).

Among the children who did not have reported food allergies at age one, those who were exclusively breastfed for at least four months had an aOR of 0.51 (p=0.07) for developing food allergies, but this effect was not seen in the high-risk group.

Past studies have also found that children from wealthier, more-educated families are more likely to have food allergy, Dr. Luccioli noted. The mechanism behind the link isn't clear, he added, although one factor could be that these children have better access to health care and are thus more likely to receive a diagnosis of food allergy.

The researchers found no association between when complementary foods were introduced, or which foods children were given, and their food allergy risk; Dr. Luccioli pointed out that the number of children given potentially allergenic foods before six months of age was very low.

Some studies have found benefit of exclusive breastfeeding in reducing allergy risk, he and his colleagues note, although these benefits were limited to atopic children with specific food allergies and lasted only up to a few years of age.

"Our results instead seem to show a breastfeeding benefit for nonatopic children and are consistent with the Tasmanian Asthma Study, which, adjusting for familial risk factors of maternal, paternal or sibling atopy, found reduced odds of reported physician-diagnosed food allergies in 7-year-old children who were exclusively breastfed for at least three months," they write.

"This potential benefit was not observed among the high-risk atopic children (in the current study), which suggests the need to separate children according to atopic risk when studying preventive benefits of exclusive breastfeeding on food allergy," the researchers conclude.

Dr. Kate Grimshaw, a senior research fellow at the University of Southampton, UK, who studies infant feeding practices and food allergy risk, had several concerns about the new findings.

For one, she pointed out, the current study included only 52% of the original cohort. "The likelihood of skewing in the data is therefore very high but at no point is there any comparison to the baseline data of the original cohort, which is needed to make an accurate analysis as to how selective this data may be," Dr. Grimshaw told Reuters Health by email. "Consequently the stated prevalence of probable food allergy at 6.34% is unlikely to be representative of the general population."

The outcome measure of "probable" food allergy as determined by reported physician diagnosis is also a potential source of error, she added, while the feeding data could be subject to recall bias given that it was reported retrospectively.

Another issue, according to Dr. Grimshaw, was that the authors reported breastfeeding to be exclusive even if infants had been given formula whilst in the hospital.

"It may be this point alone that is the cause of the authors finding no protective association between exclusive breastfeeding and allergy outcome, not that it doesn't exist," she added. "Indeed there has been previous research to show that early formula use in the first days and weeks of life is strongly associated with the later development of food allergy."

Dr. Grimshaw concluded: "Whilst interesting, I do not believe this study to be robust enough to be putting into question the current American Academy of Pediatrics (AAP) allergy prevention recommendations and the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) recommendations to not introduce solids before 4-6 months of age. It also is not robust enough to put into question the AAP breastfeeding recommendation that breastfeeding should continue whilst solids are introduced into the diet."

SOURCE: http://bit.ly/1r7Xwdl

Pediatrics 2014;134:S21-S28.

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