Lactobacillus reuteri for Infant Colic: The Science Behind Baby Calm™

Lactobacillus reuteri is one of the few probiotics with clinical evidence in infant colic. Almost all of that evidence comes from a single strain, L. reuteri DSM 17938, tested in breastfed babies. Baby Calm™, ELMED Life Sciences' L. reuteri drop, belongs to this category of colic support products.

Quick Answer

Randomized trials show that L. reuteri DSM 17938 can shorten daily crying time in breastfed infants with colic. ESPGHAN (the European Society for Paediatric Gastroenterology, Hepatology and Nutrition) supports doctors considering the strain for this group. In formula-fed infants the data are too thin to recommend for or against it.

What Counts as Infant Colic?

Doctors use the Rome IV criteria. A baby has colic if they are under 5 months old, have long spells of crying or fussing with no obvious cause, and are otherwise well. That means no fever, no illness and normal growth. You may still hear the older "rule of threes", meaning more than 3 hours of crying a day, on more than 3 days a week, for at least 3 weeks.

The crying usually builds through the first month, peaks around six weeks and eases by three to four months. Knowing that colic follows this pattern helps parents more than most people expect.

The cause is still debated. Gut immaturity, extra-sensitive gut nerves and an altered gut microbiome all have some research behind them. The microbiome theory is the reason probiotics came into the picture.

How Could L. reuteri Reduce Colic Symptoms?

Stool studies have found that colicky babies tend to carry fewer lactobacilli and more gas-producing bacteria than calmer babies. Giving L. reuteri appears to shift that balance in some infants.

Animal research suggests a second effect on the gut itself. The strain seems to settle irregular intestinal contractions and lower how strongly gut nerves respond to stretching. Whether this happens in human babies is still uncertain. What has been measured reliably in people is the outcome parents care about, which is minutes of crying.

What Does the Research Actually Show?

The best summary comes from a 2018 individual participant data meta-analysis in The BMJ, which re-analysed the raw data from four randomized trials. Breastfed babies given DSM 17938 cried less than babies given a placebo, and the gap widened over three weeks of treatment.

Formula-fed babies did not show the same benefit. This explains why one of the larger individual trials, which enrolled both breastfed and formula-fed infants, found no improvement overall.

In most of these studies, babies received a daily dose of around 100 million CFU for 21 to 28 days. CFU stands for colony-forming units, a count of live bacteria.

Why Does the Strain Name on the Label Matter?

DSM 17938 was developed from an older strain, ATCC 55730, after scientists removed genes that carried antibiotic resistance. The colic evidence belongs to DSM 17938 specifically.

Another L. reuteri strain may behave quite differently. When you compare products, look for the full strain name and the CFU per dose. If the label gives only the species, the product cannot fairly be matched to the published research.

Where Does Baby Calm™ Fit?

Baby Calm™ provides L. reuteri as oral drops, the format used in the colic trials. Drops are easy to give to a young infant. You can place them on a spoon or nipple, or mix them into a little cooled breast milk.

Baby Calm™ Plus adds vitamin D3 to the same drop. This makes sense for breastfed babies, who generally need daily vitamin D anyway. If your baby already takes a separate vitamin D supplement, check with your pediatrician first.

When Is Crying Not Colic?

A probiotic should never delay a medical review. Your baby needs to be seen promptly if crying comes with any of the following:

• Fever, especially under 3 months of age
• Repeated or green vomiting
• Blood in the stool
• Poor feeding or poor weight gain
• Unusual drowsiness, floppiness or a high-pitched cry

Premature babies and infants who are seriously ill or have a weak immune system should start probiotics only under medical supervision.

Key Takeaways

• DSM 17938 is the most studied L. reuteri strain for colic.
• The benefit is mainly seen in breastfed infants.
• Expect gradual improvement over three to four weeks.
• Check the strain and CFU, not just the species.
• Baby Calm™ delivers L. reuteri in an infant-friendly drop.

Final Thoughts

Colic passes, but those first few months can feel long. For a breastfed baby with true colic, L. reuteri DSM 17938 is one of the few options with solid trial data behind it. Used alongside soothing, a check on feeding and regular pediatric follow-up, it can make that stretch a little easier.