Colic Is More Than Just Crying
Colic, defined as inconsolable crying for more than three hours per day, more than three days per week, for more than three weeks (the Wessel criteria), affects approximately 10 to 25% of infants in the first few months of life. For decades, colic was dismissed as a normal phase with no identifiable cause. Parents were told their babies would "grow out of it" and offered little meaningful support.
Modern microbiome research has transformed this understanding. A growing body of evidence now demonstrates that colicky infants have distinctly different gut microbiome compositions compared to non-colicky infants, and that these differences likely contribute to the excessive crying through gut inflammation, gas production, and altered gut-brain signalling.
What Research Reveals About Colic and the Microbiome
Microbial Differences in Colicky Infants
Multiple studies have found consistent patterns in the gut bacteria of colicky babies. A landmark study in Pediatrics showed that colicky infants had significantly higher levels of Proteobacteria (a phylum that includes many gas-producing species) and lower levels of Bifidobacterium and Lactobacillus compared to healthy controls.
Specifically, colicky infants showed elevated populations of Escherichia coli, Klebsiella, and other gram-negative bacteria that produce lipopolysaccharides (LPS), a potent inflammatory compound. This microbial profile promotes intestinal inflammation, excessive gas production, and visceral hypersensitivity, all of which can cause significant discomfort and crying.
Gut Inflammation and Pain Signalling
Colicky infants show elevated levels of faecal calprotectin, a marker of intestinal inflammation, compared to non-colicky infants. This inflammation sensitises the pain receptors in the infant gut, meaning that normal gut processes such as peristalsis and gas movement that a healthy infant would barely notice become painful stimuli for a colicky baby. This is analogous to the visceral hypersensitivity seen in adults with irritable bowel syndrome.
Risk Factors for Colic-Associated Dysbiosis
- Caesarean delivery: infants born by C-section are colonised by skin and environmental bacteria rather than maternal vaginal and faecal bacteria, leading to delayed Bifidobacterium establishment
- Perinatal antibiotic exposure: antibiotics given to the mother during labour (such as for Group B Streptococcus prophylaxis) significantly alter the infant's initial microbiome colonisation
- Formula feeding: breast milk contains human milk oligosaccharides (HMOs) that specifically nourish Bifidobacterium species. Formula lacks these prebiotic components
- Maternal stress during pregnancy: elevated maternal cortisol alters the vaginal and gut microbiome that the infant will inherit at birth
Evidence-Based Approaches for Colicky Babies
Probiotic Supplementation
The most studied probiotic for infant colic is Lactobacillus reuteri DSM 17938. A meta-analysis of seven randomised controlled trials found that this specific strain reduced daily crying time by an average of 50 minutes per day in breastfed infants with colic. The effect is believed to work through reducing gas-producing bacteria, decreasing gut inflammation, and improving gut motility.
It is important to note that the evidence is strongest for breastfed infants. Results in formula-fed infants have been less consistent, possibly because the absence of HMOs limits the probiotic's ability to establish itself in the gut.
Maternal Diet Modifications (for Breastfeeding Mothers)
If you are breastfeeding a colicky baby, eliminating cow's milk protein from your diet for a two-week trial period may help. Research suggests that up to 25% of colic cases in breastfed infants improve when maternal dairy is removed, likely due to cow's milk proteins passing into breast milk and triggering gut inflammation in sensitive infants.
Supporting Natural Microbiome Development
- Continue breastfeeding if possible, as breast milk provides the prebiotics that support beneficial bacterial growth
- Ensure adequate skin-to-skin contact to support microbial transfer
- Avoid unnecessary antibiotic use for both mother and infant
- Discuss probiotic options with your paediatrician, particularly L. reuteri DSM 17938
How GutIQ Helps Parents Understand Gut Health
While GutIQ is designed for adults, a parent's gut health directly influences the microbial environment they pass to their children. By identifying and addressing your own gut imbalances, you can improve the microbiome your infant inherits through breast milk, skin contact, and shared environment. GutIQ gives parents the knowledge to make informed decisions about gut health for the whole family.