Lactobacillus reuteri

Lactobacillus reuteri is a species of bacteria that belongs to one of the major lactic-acid producing genera of bacteria. It can be found in the human intestinal tract, though not always and often in relatively low numbers. Lactobacillus reuteri is also found in the gut of other mammals and birds.

Initially, Lactobacillus reuteri was used to treat necrotizing colitis, a gastrointestinal disease characterized by infection and inflammation that is particularly dangerous for infants, particularly those born prematurely. Lactobacillus reuteri was used due to its anti-inflammatory effects. The research on Lactobacillus reuteri and necrotizing colitis used the Lactobacillus reuteri strains ATCC 55730 and its daughter strain DSM 17938, both of which can survive oral supplementation.

Interest in Lactobacillus reuteri grew after research confirmed that changing aspects of the digestive system can influence the immune system. A strain of Lactobacillus reuteri called ATCC PTA 6475 has been found to improve levels of testosterone and oxytocin, as well as skin quality in animal studies. Research on animals has also found potential benefits for hair quality, bone mass and preventing weight gain from obesity-causing diets.

One of the ways Lactobacillus reuteri may work involves a kind of T cell called a Treg cell (a T cell that down-REGulates the immune system in part by producing a cytokine called IL-10). Lactobacillus reuteri increases the amount of Treg cells in the body, which suppresses the actions of another kind of T cell called a Th17 cell (which secretes IL-17). Preserving or reversing this process (either by increasing IL-10 or by blocking IL-17) appears to provide therapeutic benefits.

Lactobacillus reuteri increases the number of Treg cells in the intestines, which can then be absorbed back into the blood to benefit the rest of the body.

Certain strains of Lactobacillus reuteri are more appropriate for supplementation than others. Lactobacillus reuteri ATCC 55730, DSM 17938, and ATCC 6475 are all known to survive oral supplementation, even without an enteric capsule.

Research doses of Lactobacillus reuteri are in the range of 1x10^{9 to 1x10}11 (one billion to one hundred billion) colony-forming units (CFU) taken over the course of a day. Both single doses and multiple split doses per day have been found to be effective, though further research is needed to determine whether one is more effective than the other.

At least one study suggests that supplementing Lactobacillus reuteri every other day is just as effective as daily dosing.

Lactobacillus reuteri can be taken with food. Don’t take Lactobacillus reuteri with a hot beverage to allow for the survival of the bacteria.

Once supplementation is stopped, intestinal colonization will start to revert to normal. Further research is needed to establish the exact time frame, but it has been observed to occur between half a week to one month after supplementation is stopped. The actual time may depend on whether supplementation took place over the long term or the short term.

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects lactobacillus reuteri has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Infantile Colic	Minor	Very High See all 7 studies	Supplementation of 108 CFU of DSM 17938 (no other strain tested) has been associated with greatly reducing infantile colic within a week and increasing potency for one month, but the available evidence appears to be potentially biased and the lone independent study failed to find a protective effect of supplementation.
	Bilirubin	-	- See all 3 studies
	HDL-C	-	- See all 3 studies
	LDL-C	-	- See all 4 studies
	Liver Enzymes	-	- See all 3 studies
	Total Cholesterol	-	- See all 3 studies
	Triglycerides	-	- See all 3 studies
	Weight	-	- See all 3 studies
	Apolipoprotein A	-	- See study
	Apolipoprotein B	-	- See 2 studies
	B-Cell Count	-	- See study
	Blood Glucose	-	- See study
	Blood Pressure	-	- See 2 studies
	C-Reactive Protein	-	- See study
	Constipation	-	- See 2 studies
	Diarrhea	-	- See study
	Fecal Bile Acids	-	- See study
	Fecal Moisture	-	- See study
	Fibrinogen	-	- See study
	Heart Rate	-	- See 2 studies
	Helicobacter Pylori Infection	-	- See 2 studies
	Hematocrit	-	- See study
	Hemoglobin	-	- See study
	Immunity	-	- See study
	Immunoglobulin A	-	- See study
	Interleukin 1-beta	-	- See study
	Interleukin 10	-	- See study
	Interleukin 6	-	- See study
	Interleukin 8	-	- See 2 studies
	Kidney Function	-	- See 2 studies
	Lipid Absorption	-	- See study
	Lymphocyte Count	-	- See 2 studies
	Monocyte Count	-	- See 2 studies
	Neutrophil Count	-	- See study
	Plasma Vitamin D	-	- See study
	Plasma Vitamin E	-	- See study
	Plasma β-carotene	-	- See study
	Pulmonary Function	-	- See 2 studies
	Red Blood Cell Count	-	- See 2 studies
	Risk of Allergic Diseases	-	- See study
	Serum Platelets	-	- See 2 studies
	Symptoms of Cystic Fibrosis	-	- See 2 studies
	TNF-Alpha	-	- See 2 studies
	Upper Respiratory Tract Infection Risk	-	- See study
	White Blood Cell Count	-	- See 2 studies

Studies Excluded from Consideration

Note: The above table includes data on all strains of L. reuteri whether by capsule or via food product, but will exclude studies that use combinations of species (ie. L. reuteri with L. rhamnosus)

• Confounded with lactobacillus rhamnosus^[1][2][3]