Benefits of breastfeeding in preventing asthma cancelled out by fast-food diet

Many studies have shown that breastfeeding appears to reduce the chance of children developing asthma. But a newly published study led by a University of Alberta professor has found that eating fast food more than once or twice a week negated the beneficial effects that breastfeeding has in protecting children from the respiratory disease.

The article appears online in the international journal Clinical and Experimental Allergy based in London, England. A number of different findings led the researchers to their conclusion – showing links between fast food and asthma, breastfeeding and asthma, and all three together.

"Like other studies, we found that fast-food consumption was associated with asthma," said the senior author, Dr Anita Kozyrskyj (pronounced koh-ZUHR-skee), an associate professor in the Department of Pediatrics in the U of A's Faculty of Medicine & Dentistry.

The research confirmed the findings of many other studies about the benefits of breastfeeding in relation to asthma. Kozyrskyj et al. found that breastfeeding for too short a time was linked to a higher risk of asthma, or conversely that children exclusively breastfed 12 weeks or longer as infants had a lower risk.

"But this beneficial effect was only seen in children who did not consume fast food, or only occasionally had fast food," she added.

More than half the children studied ate fast food more than twice a week.

The researchers suggested the prevalence of fast food in today's society may explain why asthma rates keep rising even though more mothers are breastfeeding.

The group did not look at why fast food might cause asthma. But the authors suggest the high fat content, and high salt levels (which can increase twitchy airways and wheezing) may be to blame.

Kozyrskyj, an authority in the area of child health and asthma research, was recruited to the University of Alberta from the University of Manitoba to assume the position of Research Chair, Maternal–Child Health and the Environment.

She conducted the study with Dr Allan Becker while at the University of Manitoba. The team looked at about 700 Manitoba children, about 250 of whom had asthma and 475 who did not. The research was funded by the Canadian Institutes of Health Research and the analyses were conducted by Xiao-Mei Mai, a postdoctoral student at the U of M.

Kozyrskyj noted that nutrition is only one of many factors involved in asthma. "But this is an interesting finding, and we hope it will stimulate other researchers to follow up and investigate this in more depth, perhaps with a cohort study."

She was a co-author in a different study that received widespread publicity last year when the researchers reported children who received antibiotics in the first year of life were at higher risk of developing asthma later on.

(Source: University of Alberta Faculty of Medicine & Dentistry: Clinical and Experimental Allergy: March 2009)