Rk. Woods et al., DO DAIRY-PRODUCTS INDUCE BRONCHOCONSTRICTION IN ADULTS WITH ASTHMA, Journal of allergy and clinical immunology, 101(1), 1998, pp. 45-50
Background: Dairy products have often been implicated as a cause of ex
acerbation of asthma, but there is little scientific evidence to suppo
rt this hypothesis. Objective: We sought to determine whether dairy pr
oducts induce bronchoconstriction in a group of adults with asthma. Me
thods: Twenty subjects with asthma (13 women and 7 men) were recruited
from respondents who had previously completed a food and asthma quest
ionnaire. Ten subjects perceived that their asthma became worse with i
ngestion of dairy products (positive perceivers), whereas ten were neg
ative perceivers. None of the subjects had positive skin prick test re
sults with cow's milk The study was a randomized, cross-over, double-b
lind, placebo-controlled trial. Subjects complied with a dairy-free di
et throughout the study. The active challenge was a single-dose drink
equivalent to 300 ml of cow's milk. A positive reaction was defined as
a 15% reduction in both FEV1 and peak expiratory dow (PEF) on the act
ive challenge day compared with results obtained at the same time on t
he placebo day. Results: For both FEV1 and PEF there were no statistic
ally significantly differences in group means between active challenge
and placebo challenge, between sequence of administration, or between
perceptions. Nine subjects showed FEV1 or PEF changes that were great
er than 15% of baseline values: four patients shelved changes after bo
th active and placebo treatment; two after treatment with placebo only
; and three after active treatment alone. Of the latter group, two sub
jects showed changes only in PEF, and when one of these subjects under
went a further detailed study, no asthmatic reaction could be demonstr
ated. Conclusion: It is unlikely that dairy products have a specific b
ronchoconstrictor effect in most patients with asthma, regardless of t
heir perception.