Benefits
Infant digestive comfort: less crying in breastfed babies (DSM 17938)
A pooled analysis of individual data from four double-blind trials (345 infants with colic) found that infants given DSM 17938 cried and fussed about 25 minutes less per day than with placebo at day 21 and were about 1.7 times as likely to reach treatment success. The effect was large in breastfed infants and not significant in formula-fed infants. Discuss any infant probiotic with a pediatrician.
LDL cholesterol support (NCIMB 30242 capsules)
In a 9-week double-blind trial in which 127 adults with high cholesterol completed the study, NCIMB 30242 capsules lowered LDL cholesterol by 11.6 percent, total cholesterol by 9.1 percent and apolipoprotein B-100 by 8.4 percent versus placebo, while HDL cholesterol and triglycerides did not change. These are blood lipid markers from one trial, not heart outcome data.
Gum health support in a pregnancy lozenge trial
In a randomized placebo-controlled trial in 45 pregnant women with gum inflammation, lozenges with L. reuteri ATCC PTA 5289 and DSM 17938, taken twice daily for about 7 weeks until birth, led to lower gingival index and plaque index scores than placebo. It was one small trial, used alongside normal oral hygiene.
Mechanism of action
Reuterin production
L. reuteri can make reuterin (3-hydroxypropionaldehyde) when it ferments glycerol, and reuterin is active against a range of microbes in laboratory tests. Whether this contributes to the effects seen in human trials has not been shown.
Bile salt hydrolase activity
NCIMB 30242 has bile salt hydrolase activity, which breaks apart bile acids in the gut. In the 9-week capsule trial, blood deconjugated bile acids rose and plant sterols such as campesterol and sitosterol fell by about 34 to 42 percent, which the authors read as reduced sterol absorption.
Proposed effects on gut motility and pain signaling
Researchers have proposed that DSM 17938 eases infant crying through effects on gut motility, pain signaling and local inflammation. These ideas come mainly from laboratory and animal work and were not measured in the cited infant trials.
Vitamin B12 and folate production
Some L. reuteri strains can make vitamin B12 (cobalamin) and folate in laboratory culture. How much reaches the person taking the probiotic is unclear, so it should not be relied on as a vitamin source.
Clinical trials
Individual participant data meta-analysis of 4 double-blind randomized placebo-controlled trials of DSM 17938 given orally to infants with colic, with crying and fussing time and treatment success at 21 days. (Sung et al. 2018, Pediatrics)
345 infants with colic (174 probiotic, 171 placebo).
The probiotic group cried and fussed less than placebo at all time points, with an adjusted difference of 25.4 minutes per day at day 21, and was about 1.7 times as likely to reach treatment success. The effect was large in breastfed infants (number needed to treat 2.6) and not significant in formula-fed infants, where the authors found too little data to draw conclusions.
Randomized, double-blind, placebo-controlled, parallel-arm multicenter trial of NCIMB 30242 capsules or placebo capsules for 9 weeks; the primary outcome was LDL cholesterol versus placebo. (Jones et al. 2012, Eur J Clin Nutr)
127 adults with high cholesterol completed the study.
Versus placebo, LDL cholesterol fell 11.64 percent, total cholesterol 9.14 percent, non-HDL cholesterol 11.30 percent and apolipoprotein B-100 8.41 percent. HDL cholesterol and triglycerides did not change. hs-CRP fell by 1.05 mg/L, blood deconjugated bile acids rose and plant sterol levels fell, suggesting reduced sterol absorption.
Randomized placebo-controlled trial of lozenges with at least 10^8 CFU each of ATCC PTA 5289 and DSM 17938, or placebo lozenges, taken twice daily from the third trimester until birth (about 7 weeks). (Schlagenhauf et al. 2016, J Clin Periodontol)
45 healthy pregnant women with pregnancy gingivitis (24 probiotic, 21 placebo).
Gingival index and plaque index did not differ at baseline. After birth, both were significantly lower in the probiotic group than with placebo (p < 0.0001). Blood TNF-alpha was lower in the probiotic group at baseline and no longer differed at the end. The authors described the lozenges as a possible adjunct for gum care in pregnancy.