Lactobacillus rhamnosus is a species of bacteria commonly found on and in the human body. It often resides in the gut microbiome – the trillions of microbes that live in your intestines.
Its name actually changed to Lacticaseibacillus rhamnosus a few years ago. In any case, this microbe is widely known by the shortened name L. rhamnosus.
Manufacturers sometimes add L. rhamnosus to probiotics, and it also lives in many fermented foods, like yoghurt, sauerkraut, kimchi, kombucha, kefir, sourdough bread and some cheeses.
Because L. rhamnosus is generally associated with health benefits, experts consider it to be a species of beneficial bacteria. These rod-shaped microbes often link up to create chains.
In this article, we’ll explain the potential health benefits of L. rhamnosus and cover any side effects or warnings to be aware of. But first, a little history.
L. rhamnosus explained
L. rhamnosus is a widely studied species of probiotic bacteria.
There are many strains of L. rhamnosus, and the most well-known is called L. rhamnosus GG. It gets the double G from the two scientists who first described it in the 1980s: Sherwood Gorbach and Barry Goldin.
These scientists found that L. rhamnosus GG could survive in the stomach – a fiercely acidic environment – for longer than most bacteria.
This endurance, and its ability to stick to the cells that line your intestines, make it a promising probiotic. Since its discovery, L. rhamnosus has been investigated in several hundred clinical trials, making it one of the most-studied probiotic bacteria.
Health benefits of L. rhamnosus
Below, we’ll explain some of the health benefits linked to this species of bacteria.
Diarrhoea associated with antibiotics
A common side effect of antibiotic treatment is diarrhoea. This can be unpleasant, and because it involves rapidly expelling water, diarrhoea can be dangerous for children and for adults with certain illnesses.
A 2015 review and meta-analysis that included data from 1,499 participants in 12 studies concluded that treatment with L. rhamnosus roughly halved the risk of diarrhoea after taking antibiotics.
Although the effect was most pronounced for children, overall, the authors conclude that L. rhamnosus ‘is effective in preventing antibiotic-associated diarrhoea in children and adults treated with antibiotics for any reason.’
L. rhamnosus may also be effective at reducing diarrhoea associated with cancer treatments, like chemotherapy.
IBS
Irritable bowel syndrome (IBS) is a common gut condition characterised by symptoms such as bloating, stomach cramps, constipation and diarrhoea. These symptoms tend to come and go over time.
Scientists have investigated probiotics, including L. rhamnosus, as a way to help manage the condition.
A number of studies have looked at multi-strain probiotics that include L. rhamnosus and found benefits for people with IBS.
One study compared a low-FODMAP diet – a common treatment for IBS – with L. rhamnosus. They found that both improved symptoms and the quality of life for people with IBS, compared with no treatment.
Protection from ‘bad’ gut bacteria
L. rhamnosus appears to help fend off ‘bad’ bacteria in a number of ways.
As we mentioned earlier, L. rhamnosus can adhere to the lining of your intestines. Experts believe that this ability may help these bacteria outcompete ‘bad’ bacteria as they try to get a foothold in your gut lining.
Similarly, there’s some evidence that L. rhamnosus can stick to the mucus in your intestines, preventing other microbes from setting up shop there, too.
Also, L. rhamnosus produces lactic acid, which makes the environment around these bacteria slightly more acidic. In general, ‘bad’ bacteria don’t survive well in these conditions.
Oral health
L. rhamnosus lozenges and tablets may help reduce the risk of tooth decay and other oral health problems – though how this works isn’t entirely clear.
Meanwhile, one review which looked at milk containing L. rhamnosus concluded that it was the most ‘promising’ probiotic strain for reducing the risk of tooth decay.
It seems that L. rhamnosus may outcompete ‘bad’ oral bacteria by sticking to teeth and preventing other species from attaching, as in the lining of the gut.
L. rhamnosus might also produce certain chemicals that kill competing microbes.
Weight loss
Some evidence suggests that L. rhamnosus might aid weight loss. According to the authors of one review, this effect may be most pronounced when a person follows a low-calorie diet.
The authors of another review suggest that probiotics containing L. rhamnosus might achieve this in a number of ways.
They suggest that these bacteria can influence certain metabolic processes associated with weight gain, including:
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the production of fat tissue
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the amount of heat produced in the body
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inflammation
Gastroenteritis
Gastroenteritis, sometimes called stomach flu, is inflammation of the gut most commonly caused by bacteria. Symptoms are unpleasant and generally include nausea and vomiting, stomach pain and diarrhoea.
There is moderate evidence that L. rhamnosus can help relieve symptoms for children with this type of infection.
Because this probiotic is safe, the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommend it for treating acute gastroenteritis in otherwise healthy infants and children.
Possible side effects
Probiotics and foods containing L. rhamnosus have been widely consumed for decades without serious side effects. As such, experts consider them safe.
However, if you have a chronic health condition that means you're immunocompromised, speak to your doctor before trying a new probiotic supplement.
Side effects are rare, but like other probiotics, L. rhamnosus might cause excess wind and bloating when you first start taking it in supplements. Generally, these symptoms improve after you’ve taken the supplements for a while.
Frequently asked questions
Below, we answer some common questions about this probiotic.
How can you get Lactobacillus rhamnosus naturally?
L. rhamnosus naturally occurs in certain fermented foods, including yoghurt, sauerkraut, kimchi, kombucha, kefir, sourdough bread and some cheeses.
What disease does Lactobacillus rhamnosus cause?
L. rhamnosus doesn’t cause a disease. Very rarely, it might cause an infection. However, overall, experts consider this probiotic to be very safe.
Summary
L. rhamnosus is one of the most well-studied probiotic bacteria. It’s generally considered to be a ‘good’ microbe.
Evidence suggests that L. rhamnosus may help reduce antibiotic-related diarrhoea, support gut health, lower the risk of tooth decay, reduce symptoms of IBS and aid weight loss for some people.
This bacteria occurs in fermented dairy products and a wide range of probiotic supplements and drinks.
Side effects are likely to be minimal, and L. rhamnosus is safe for most people.
To learn more about other gut health topics, visit Symprove’s Gut Hub.
Sources
A randomized, double-blind, placebo-controlled trial: The efficacy of multispecies probiotic supplementation in alleviating symptoms of irritable bowel syndrome associated with constipation. BioMed Research International. (2016). Link.
Effect of Lactobacillus on body weight and body fat in overweight subjects: A systematic review of randomized controlled clinical trials. International Journal of Obesity. (2017). Link.
Effect of probiotics Lactobacillus rhamnosus and Lactobacillus plantarum on caries and periodontal diseases: A systematic review. Dentistry Journal. (2024). Link.
Ehealth: Low FODMAP diet vs Lactobacillus rhamnosus GG in irritable bowel syndrome. World Journal of Gastroenterology. (2014). Link.
Lacticaseibacillus rhamnosus: A suitable candidate for the construction of novel bioengineered probiotic strains for targeted pathogen control. Foods. (2020). Link.
Lacticaseibacillus rhamnosus HA-114 improves eating behaviors and mood-related factors in adults with overweight during weight loss: A randomized controlled trial. Nutritional Neuroscience. (2022). Link.
Lactobacillus bacteremia during a rapid increase in probiotic use of Lactobacillus rhamnosus GG in Finland. Clinical Infectious Diseases. (2002). Link.
Lactobacillus rhamnosus GG: An overview to explore the rationale of its use in cancer. Frontiers in Pharmacology. (2017). Link.
Lactobacillus rhamnosus GG genomic and phenotypic stability in an industrial production process. Applied and Environmental Microbiology. (2020). Link.
New names for important probiotic Lactobacillus species. (2020). Link.
Probiotic, postbiotic, and paraprobiotic effects of Lactobacillus rhamnosus as a modulator of obesity-associated factors. Foods. (2024). Link.
Probiotic research priorities for the healthy adult population: A review on the health benefits of Lactobacillus rhamnosus GG and Bifidobacterium animalis subspecies lactis BB-12. Cogent Food and Agriculture. (2018). Link.
Probiotics for the prevention of antibiotic-associated diarrhea in adults. A meta-analysis of randomized placebo-controlled trials. Journal of Clinical Gastroenterology. (2021). Link.
Randomised clinical trial: A liquid multi-strain probiotic vs. placebo in the irritable bowel syndrome – a 12 week double-blind study. Alimentary Pharmacology and Therapeutics. (2014). Link.
Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Alimentary Pharmacology and Therapeutics. (2015). Link.
Thirty years of Lactobacillus rhamnosus GG: A review. Journal of Clinical Gastroenterology. (2019). Link.
Unlocking the potential of probiotic administration in caries management: A systematic review. BMC Oral Health. (2024). Link.
Use of probiotics for management of acute gastroenteritis. Journal of Pediatric Gastroenterology and Nutrition. (2014). Link.
