Some infants between 1 week and 4 months of age cry a lot without an apparent reason, a phenomenon traditionally called “infant colic.” The word “colic,” derived from the Greek word for the intestine, implies that the crying is caused by gastrointestinal disorder and pain. This inference remains controversial.1,2 For research purposes, 1- to 4-month-old infants who cry ≥3 hours per 24 hours across a specified number of days are said to have colic.1,3
In 2007, Savino et al3 identified promising support for a gastrointestinal explanation of the crying. In their randomized controlled trial, they found that the probiotic Lactobacillus reuteri reduced the crying duration of infants with colic, compared with a placebo.3 Other researchers identified gut microbiota differences between infants with colic and controls.4,5 Double-blind randomized controlled trials followed and led to the meta-analysis by Sung et al6 examined here.
In many ways, this meta-analysis6 is an exemplary piece of 21st-century science. Supported by an international scientific association, researchers from different institutes and countries conducted a systematic literature review and combined and analyzed the resulting data from studies in 4 countries (Italy, Poland, Australia, and Canada). The strengths of their meta-analysis include the use of an individual …
Address correspondence to Ian St James-Roberts, PhD, Thomas Coram Research Unit, 27-28 Woburn Square, London WC1H 0AA, UK. E-mail: