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SupplementModerate evidenceImmunity

Lactobacillus reuteri DSM 17938

Strain-specific probiotic with meta-analysis support for reducing infant colic crying time.

Why

Lactobacillus reuteri DSM 17938 (a derivative of the original L. reuteri ATCC 55730, with the resistance plasmids removed) is the probiotic strain with the strongest evidence in infantile colic. The Sung 2018 meta-analysis of breastfed infants reported approximately 25 minutes/day reduction in crying time and increased treatment success at 21 days. Effect in formula-fed infants is less consistent, strain-specific and population-specific.

How it works

Produces reuterin, a broad-spectrum antimicrobial, with activity against gas-producing infant gut bacteria (E. coli, Klebsiella). Modulates substance P signalling in enteric neurons, possibly underlying the analgesic-on-colic effect.

Expected onset · Colic crying-time reduction often by day 7–14; effect window is the first 3 months

How to take

Dosage

Infants: 1 × 10⁸ CFU (5 drops) once daily. Adult use in functional dyspepsia or H. pylori adjunct trials uses higher doses; consult product label.

Timing

Once daily; for breastfed infants, often before a feed

On the label

Specifically 'L. reuteri DSM 17938' (BioGaia is the principal commercial source). Other L. reuteri strains are not equivalent.

Ideal for

Breastfed infants with colic (under paediatric guidance); adults exploring strain-specific probiotic options for functional GI symptoms.

Safety

Coordinate paediatric use with the GP or paediatrician. Generally very well tolerated. Some products contain sunflower oil as carrier. Note for sunflower-allergic infants.

Evidence

At a glance

Sung 2018 Pediatrics individual-participant-data meta-analysis (4 RCTs, n=345 colicky infants): L. reuteri DSM 17938 reduced crying duration by ~25 min/day and doubled treatment success rate in breastfed infants vs placebo at 21 days. Effect smaller and less consistent in formula-fed infants, strain plus population both matter.

Where to get it

Shop Lactobacillus reuteri DSM 17938 on Amazon

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