Transient lactose intolerance has been identified as a possible causative f
actor in infant colic. A double-blind randomised placebo-controlled crossov
er study to investigate this has been undertaken in 53 babies with symptoms
of colic. Pre-incubation of the feed with lactase resulted in breath hydro
gen levels and total crying time which were both at least 45% lower than fi
gures with placebo treatment, in 26% of the full trial group (95% confidenc
e interval 12.9% to 44.4%), and in 38% of compliers (95% confidence interva
l 18.8% to 59.4%). The remainder did not respond to the same extent. These
findings suggest that infant colic may have a multiple aetiology, and that
in a significant number of cases the immediate cause is transient lactose i
ntolerance, in which cases pretreatment of feeds with lactase can result in
considerable symptomatic benefits.