Longer breastfeeding may increase, not decrease, the risk of a common itchy skin condition called atopic dermatitis that develops in about 12 percent of babies, a new study from Taiwan suggests.

Atopic dermatitis is a type of eczema, or skin inflammation, that runs in families and usually shows up before a baby’s first birthday. Although it can last a lifetime, it often clears up by age 5. Beyond the genetic connection, doctors don’t know why some kids develop it and others don’t. Researchers from Taiwan wanted to know if breastfeeding and the timing of first solid foods might make a difference.

It is widely believed that prolonged breastfeeding and delaying the introduction of solid foods have benefits with regard to atopic dermatitis, but clearcut scientific evidence that these feeding practices prevent the skin condition is lacking.

To investigate, Chao-Hua Chuang, and colleagues at Chang Jung Christian University and other institutions in Taiwan, looked at information from a large ongoing study of Taiwanese children.

When the children were 6 and 18 months old, their parents provided relevant information about themselves, their babies, and their home environment. The parents answered questions about smoking habits, allergies, and their level of education. They also indicated whether their child was still breastfeeding, if and when solid foods were introduced, and whether their child had been diagnosed by a doctor with atopic dermatitis.

At 18 months, 2,449 of 20,172 children (about 12 percent) had been diagnosed with atopic dermatitis - a number in line with previous studies.

The researchers excluded a large number of children who were diagnosed before they were 6 months old for fear that their parents might have changed the way their kids were fed after the diagnosis, thus skewing the data. Of the 18,773 children that remained, 1,050 (almost 6 percent) were diagnosed with atopic dermatitis between the ages of 6 and 18 months.

After controlling for possible risk factors for atopic dermatitis - such as parents’ allergies, and pets, mold, and exposure to secondhand smoke in the home - they found that not only did longer breastfeeding not protect against the skin condition as might have been expected, it appeared to increase the risk that a child would have atopic dermatitis at 18 months.

In the journal Pediatric Allergy and Immunology, the researchers acknowledge that their results fly in the face of some previous studies that have suggested that children who are breastfed are less likely to develop eczema.

Chuang and colleagues point out, however, that most previous studies focused on exclusive breastfeeding, something they could not do because few Taiwanese parents exclusively breastfeed their children without adding other liquids or solids. As a result, they say they “cannot totally dismiss the supposed benefits of exclusive breastfeeding with regard to atopic dermatitis.”

In an email to Reuters Health, Chuang emphasized that the evidence from the current study does not warrant a change in breastfeeding practice. “We can not exclude the other potential benefits of breastfeeding,” Chuang wrote.

The timing for introducing solid foods was the other focus of the Taiwan study. Delaying solid foods did not appear to affect atopic dermatitis risk one way or the other, prompting the researchers to suggest that current feeding guidelines that recommend delaying solids to reduce allergies “need to be reconsidered.”

The latest review (2008) of evidence by the American Academy of Pediatrics concluded that infants at high risk of developing allergic diseases (including dermatitis) might benefit from exclusive breastfeeding for 4 months but for infants in general, “after 4 to 6 months of age, there are insufficient data to support a protective effect of any dietary intervention for the development of atopic disease.”

SOURCE: Pediatric Allergy and Immunology, published online June 21, 2010