Fast food negates breastfeeding's protective effect on asthma, report Canadian researchers in the April issue of Clinical and Experimental Allergy. They found that infants exclusively breastfed 12 weeks or longer had low rates of asthma in childhood, unless they ate fast food more than twice weekly. In that case their asthma risk doubled, as compared with children who'd been similarly breastfed as infants and who ate fast food less often than twice weekly. Moreover, asthmatic children eight to 10 years of age are nearly twice as likely to eat fast food as nonasthmatic children are. The researchers speculate that fast food, which is high in sodium, affects bronchial hyperresponsiveness and wheezing.