LRGG – Lacticaseibacillus Rhamnosus GG. 

Lactobacillus rhamnosus GG (ATCC 53103) is one of the world’s most thoroughly studied bacterial strains, featured in over 250 human clinical trials, many of these are Randomised Double Blind Placebo-Controlled Trials (RCT’s), the gold standard in clinical testing used by most modern pharmaceuticals and medical research bodies.

First discovered in 1983 by Dr Sherwood Gorbach and Dr Barry Goldin (hence the “GG”), this strain has been researched across digestive, immune, and developmental areas to name but a few. Having been studied so broadly and in so many contexts it has rapidly become a global benchmark in microbial science. It was originally found in a human gut sample, which means it’s a naturally occurring human strain, not developed in a lab.

In April of 2020 Lactobacillus Rhamnosus GG was officially reclassified as Lacticaseibacillus Rhamnosus GG as part of a taxonomic revision of the genus Lactobacillus, but most people just call it LGG or LRGG.

At BetterGuts, we use L. rhamnosus GG for its incomparable depth of research, its proven survivability through stomach acid, and its record of safe use across ages.

Scientific Background

For more than 30 years LRGG has been carefully studied by many different research bodies across the world, in many different contexts and alongside many different health conditions, and the result is a body of research that almost can’t be matched by any other bacteria used in supplements today.

Studies have indicated that LGG can:

-       Support a balanced gut environment, especially when the gut is under stress, for example, after antibiotic use or during bouts of other gastrointestinal issues such as IBS.

-       Survive exposure to stomach acid and bile salts

-       Temporarily adhere to intestinal cells

-       Coexist with other beneficial species

LRGG has become the centrepiece of global microbiome research, and has so much evidence behind it now that it is often used as the main reference point for studies into other bacteria! At BetterGuts we love the science, and we could talk all day about all the amazing areas of research this bacterium has been studied in, so let us take you on a little journey to examine just a few those areas and the amazing results they found.

Use alongside Antibiotics and AAD.

Overview

When antibiotics are prescribed, they don’t just act on the bacteria that cause infection, they also affect the community of friendly bacteria that live in your gut. This can sometimes lead to temporary digestive changes such as loose stools, bloating, or discomfort, with serious cases experiencing diarrhoea. Antibiotics have become very common medications in the world today, and as their use has grown, so has the research into pairing them with a good probiotic to help rebuild.

That’s where Lactobacillus rhamnosus GG (LGG) comes in. It’s one of the few bacterial strains that has been extensively studied for how it behaves in the gut during antibiotic use, and the results across several clinical trials have been remarkably consistent.

What the research shows

In a number of high-quality human studies, groups taking LGG alongside antibiotics experienced a dramatic reduction in the number of people who developed diarrhoea compared with those taking a placebo.

-       In one major trial with 167 children, only around 5 % of those taking LGG experienced antibiotic-related diarrhoea, compared with 16 % in the placebo group, a difference of roughly 70 % fewer cases.

-       Another study with over 200 children saw a similar pattern: 8 % vs 26 %, confirming that far fewer participants experienced disruption when LGG was part of their routine.

-       A large meta-analysis reviewing data from more than 1500 participants found the same trend; those taking LGG had about two-thirds lower risk of antibiotic-associated diarrhoea overall.

Not only were episodes less common, but when they did occur, they were also shorter-lived, typically lasting one to two days instead of four or more.

Why it matters to you

The research suggests that LGG helps to stabilise the natural bacterial balance in the gut while it’s under stress. By keeping this environment more balanced, participants reported fewer bouts of loose stools, and less bloating, flatulence, and general digestive upset during antibiotic therapy. In one adult trial, people taking LGG alongside a common antibiotic course described a calmer, more comfortable digestion, and many found it easier to complete their medication without side-effects getting in the way.

If you’re taking antibiotics, your gut is working harder than usual to rebalance itself as the antibiotics can target beneficial bacteria as well as harmful ones. This is where LGG can step in to calm the situation and reduce the impact.

The science has promising results, and across multiple studies, people taking LGG consistently experienced:

-       Fewer interruptions to their normal routine

-       Shorter and milder bouts of digestive discomfort

-       A smoother, calmer gut experience overall during antibiotic use

In short: Lactobacillus rhamnosus GG has been one of the most widely researched strains in the world for its interaction with the gut during times of stress, especially during antibiotic treatment. Antibiotics are lifesaving medications, but they can cause disruption, and the results of studies into LGG’s effect on the gut during this period speak for themselves.

Acute Gastroenteritis and Diarrhoea

Overview

When the digestive system is unsettled, for example during bouts of acute gastroenteritis, the body works hard to restore balance. Symptoms like loose stools, discomfort, and dehydration can occur quickly, particularly in young children, and can be very unpleasant.

That’s why Lactobacillus rhamnosus GG (LGG) has been studied so extensively in this area: to understand how certain bacterial strains might help the gut recover its balance more efficiently. The bulk of the studies into this area come in the form of RCT’s, ensuring that the results are fair, and that high standards are maintained throughout.

What the research found

Across multiple clinical trials in children, researchers consistently found that those who received LGG alongside rehydration therapy recovered significantly faster than those who received a placebo.

-       In one landmark study, children taking LGG recovered in about 3 days, compared with nearly 6 days for those not taking it; that’s around twice as fast.

-       Another large European study with 287 children found that those given LGG recovered in 2 - 3 days on average compared to 3 – 4 days in the placebo group, and also spent less time in hospital recovering.

-       A high-dose trial in India with 200 children showed a similar trend: LGG users recovered 18 hours faster when compared to the placebo group, and had fewer stools per day as their digestion settled.

-       Other studies have also shown that LGG can reduce the amount of virus detected in the gut during illness, with one study specifically finding reduced rotavirus presence, indicating a quicker return to normal balance.

When viewed together, these studies demonstrate a consistent pattern: children receiving LGG experienced 25–50 % shorter illness durations, fewer daily symptoms, and a smoother return to normal digestion, all without any increase in side effects. Promising results indeed!

Why this matters to you

A faster recovery isn’t just about getting back to normal sooner, it’s also about feeling more comfortable along the way. Participants who took LGG described fewer loose stools, less bloating, and an overall calmer digestive experience during their recovery, and scientific research suggests that Lactobacillus rhamnosus GG can help the digestive system recover its natural rhythm more quickly when it’s been disrupted by illness.

Gastroenteritis can be a very uncomfortable condition for those who suffer from it, and whilst there are many pharmaceutical approaches to treating this condition in both adults and children, the ever growing body of high quality research behind LGG in this context, and the consistently positive results these studies have shown, demonstrates that it most certainly merits real attention in this area.

The Immune System

Your immune system and your gut are deeply connected, around 70% of your body’s immune cells live in or around the intestinal wall. That means a calm, balanced gut and digestive environment can play a key role in supporting overall immune stability.

Lactobacillus rhamnosus GG (LGG) has been one of the most intensively studied bacterial strains in this area, with numerous RCT’s conducted to find out if LGG can interact with, and even help, the immune system. With landmark studies involving large groups of people and powerful findings, this is a very promising area of research into this remarkable bacterium.

What the studies show

Over the past three decades, scientists have explored how LGG interacts with the gut lining and the immune system in both children and adults, and the findings have been consistently encouraging. Here are just a few of the studies undertaken and the results they found.

Fewer infections and fewer missed days

In a landmark study involving 571 children attending day-care centres, those who drank milk containing LGG every day for seven months had 15% fewer sick days than children who received ordinary milk.

They also needed fewer antibiotics overall, 44% in the LGG group compared to 54% in the placebo group.

Another large trial of 742 children turned up similar results: the trial found that giving LGG to hospitalised children reduced their chance of picking up hospital-acquired GI and respiratory infections, and when infections did occur, they were less frequent and less prolonged.

In both studies, children taking LGG were not only ill less often, but when they did get sick, their symptoms were milder and their recoveries faster.

Immune balance, not overstimulation

In adults, researchers have focused on how LGG might help keep the immune system in balance, not by pushing it harder, but by helping it respond more calmly and efficiently.

In one controlled trial, adults taking LGG for just three weeks had significantly higher activity in their natural killer (NK) cells; the immune cells that patrol and respond to early threats; compared with those taking a placebo.

Another RCT found that LGG increased levels of interleukin-10 (IL-10), a molecule that helps regulate inflammation and maintain tolerance to everyday triggers.

These studies consistently found that LGG helped to boost immune markers in those taking it. Coupled with the studies that found a reduction in sick days and faster recovery, this makes a strong case for LGG’s effects on the immune system!  

The Wall of the Gut

The interaction between LGG and the immune system seems to start right where they meet: in the gut lining.

In one double-blind study, healthy adults taking LGG showed a measurable increase in IgA, a natural antibody found in the mucous membranes that line the intestines, nose, and mouth. IgA acts like a first line of defence, helping the body distinguish between friendly and unfriendly visitors.

This subtle but powerful response suggests that LGG can help reinforce the gut’s natural barrier, keeping the immune system balanced, alert, and at ease.

What this means for you

Taken together, these studies show that LGG doesn’t overstimulate the immune system, but rather it shows great potential to help keep it in balance. In real-world terms that means it could help to ensure fewer seasonal illnesses, with milder symptoms when they do occur, and a more settled, resilient feeling overall.

It’s demonstrated ability in studies to boost the levels of IL-10 are especially promising. This molecule is known to suppress a variety of inflammatory cytokines, such as IL-6 and TNF Alpha, helping to keep the immune system balanced, calm and precise.

Of course, many of these studies are RCT’s, keeping up LGG’s track record of scientific research held to only the highest standards in clinical testing.

Pregnancy and Early Life – Eczema

The first months of life are a crucial time for the gut and the immune system. A baby’s microbiome, the community of bacteria that line the gut, develops rapidly, helping to shape everything from nutrient absorption to immune balance.

Lactobacillus rhamnosus GG (LGG) has been one of the most extensively studied bacterial strains in infants and young children, particularly in how it supports healthy immune and gut development from the very beginning. A particularly interesting area of this research is into how this bacterium can impact the likelihood of eczema in infants, both in supplementation to the pregnant mother pre-birth, and to the infant directly.

What the studies show

Over more than two decades of research, LGG has been given to expectant mothers, newborns, and infants in carefully controlled studies, and the outcomes have been remarkably consistent, not to mention very promising.

A lasting difference in early-life balance

In one landmark study published in The Lancet, researchers followed 132 families from pregnancy through the early years of childhood.

Half the mothers took LGG daily during the last weeks of pregnancy and continued giving it to their infants after birth.

By age two, only 23% of children in the LGG group had developed early-life skin sensitivity compared with 46% in the placebo group, an amazing 50% reduction in risk.

Even more impressively, when scientists checked back at age four, that difference had persisted: 26% vs 46%, suggesting that the benefits lasted long after supplementation stopped.

Across multiple studies, the pattern holds.

Other research teams across Europe confirmed the same trend.

-       In a Finnish trial of 62 mother–infant pairs, only 15% of infants whose mothers took LGG during pregnancy and breastfeeding developed eczema by age two, compared with 47% in the placebo group

-       A meta-analysis combining results from 14 high-quality trials found that, overall, LGG use (among other probiotic bacteria) in pregnancy and infancy was linked to a 34% reduction in risk of early-life eczema.

Both the trial in the Lancet and the Finnish trial were randomised, double-blind, and placebo-controlled, meaning that neither participants nor researchers knew who was receiving LGG until the study ended, ensuring that the results were unbiased and scientifically sound. What’s more, these studies were conducted by different research organisations, giving us a wide body of evidence for the effects of LGG in early life.

How it may work

There has been some debate around how the LGG actually manages to have the impact that it has in these studies, but the leading opinions from the research teams and medical scientists are these.

In the studies in which Mothers were supplemented the LGG during pregnancy, the leading opinion here is that the positive effect in the baby was due to a positive effect to the breast milk of the Mother, that was then subsequently passed on to the baby. Scientists found heightened levels of TGF-β2 in the breastmilk, this is an anti-inflammatory cytokine, in simple terms this helps to keep the immune system calm and prevents it from overreacting, something often associated with Eczema and Allergies. It has been heavily studied, and long believed, that breast milk is a natural pathway for a Mother to pass on her immunity to the baby, and so it’s very possible that LGG can influence this pathway to help pass on a strong immune system!

In the studies in which the infants were given LGG directly, a few theories emerge. Some believe that the LGG can calm the immune system, a theory supported by the evidence that LGG can help to boost levels of IgA, as well as it’s ability to shift the immune system away from TH2 dominance, and toward a more calm and regulated state of being. But the overriding opinion here is that LGG has a great ability to adhere to the gut lining. This enables it to strengthen the gut barrier, and subsequently prevent any unwanted chemicals or molecules from getting through. In other words, LGG has shown real promise in strengthening the gut’s natural defences!  

What this means for you

For parents and parents-to-be, it’s reassuring to know that the strain being used has been through decades of clinical testing, with consistent, measurable results.

In trial after trial, children who received LGG, either through their mothers or directly, showed:

-       30–50% lower rates of early-life skin sensitivity

-       More stable immune responses

-       No increase in side effects, even with long-term use

And the benefits often persisted years after the studies ended, suggesting that early microbial balance can make a meaningful difference that lasts.

In short

Lactobacillus rhamnosus GG is one of the few bacterial strains shown in gold-standard human trials to have measurable effects during the earliest stages of life.

Across multiple countries and thousands of participants, the results have been consistent: a healthier balance in early immune development, and a lower likelihood of early skin sensitivities.

It’s science-backed, rigorously tested, and forms part of the foundation for BetterGuts’ commitment to providing precision-formulated, research-driven bacterial supplements.

Skin & Allergy Research in Adults

When it comes to skin and allergy research, Lactobacillus rhamnosus GG (LGG) is one of the most studied bacterial strains in the world — and while much of the early work focused on infants and early-life development, a growing number of studies have also explored how LGG behaves in adults, particularly in relation to seasonal allergies, immune balance, and skin reactivity.

As usual, most of these studies were RCT’s, and you’d expect nothing less from a bacterium with as much clinical research behind it as LGG.

What the science found

Seasonal Allergies and Immune Balance

In a recent RCT published in Microbiology Spectrum (2025), researchers studied adults with seasonal allergic rhinitis, more commonly known as hay fever.

Participants took a slow-release chewable containing LGG throughout the pollen season, while a control group received an identical placebo. Hay fever can be debilitating for many, and even dangerous to some, with even the mildest cases constituting a real inconvenience.

The results were striking:

LGG was shown to successfully reach the upper airways, where pollen reactions begin, and was detected in 77% of participants’ throats and 41% of nasal passages. This is important as it shows the bacteria is capable of surviving in the impacted areas of the airway.

Those taking LGG also showed lower levels of key inflammation-related immune markers, including IL-4 and IL-13, compared with the placebo group.

This suggests LGG may help the body maintain a calmer, more balanced immune response when exposed to common seasonal triggers, an emerging theme in research into LGG across various medical contexts.

Importantly, the study confirmed that the bacteria remained active and viable where it matters most, demonstrating LGG’s ability to interact directly with immune cells along the respiratory tract.

Pollen Sensitivity and Mucosal Immunity

Another randomised, double-blind trial explored how LGG might influence the body’s natural defences in adults with birch-pollen allergy and oral allergy syndrome, a condition where certain foods can trigger mild reactions in pollen-sensitive individuals.

Over a period of five and a half months, adults who took LGG daily showed increased levels of allergen-specific IgA antibodies in their saliva compared with those on placebo. IgA antibodies are part of the body’s first line of immune defence, helping to stabilise mucosal surfaces such as the mouth, nose, and throat.

This finding indicates that LGG has the potential to modulate local immune activity in a beneficial direction, supporting the body’s natural tolerance processes through it’s effects on immune markers.

What this means for you

Across the adult studies, a consistent picture emerges:

-       LGG has been shown in gold-standard clinical trials to interact with the immune system in measurable ways.

-       It has demonstrated local effects in the mouth, throat, and nasal passages, helping to maintain calm immune communication in response to allergens.

-       Some participants experienced improved immune balance during high-pollen seasons, with no reported side effects.

While more research is still ongoing, these studies demonstrate a promising trend in LGG research suggesting that it is capable of supporting the immune system’s balance, and through that, helping to prevent the immune overreactions that we have come to know as allergies.

In short

Lactobacillus rhamnosus GG is one of the few bacterial strains studied across all life stages, from infancy to adulthood.

In adults, it has shown promising results in helping the body maintain immune stability and mucosal balance in the face of common allergens, with studies using rigorous gold-standard testing methods and showing measurable biological changes compared with placebo.

The Gut–Brain Axis: How the Gut Talks to the Mind – Studies into Cognitive function and Wellbeing.

In recent years, scientists have discovered that the gut and the brain are deeply connected, a communication pathway known as the gut–brain axis. Through this network, bacteria in the digestive tract can influence how we feel, think, and respond to stress.

One of the most exciting areas of new research focuses on LGG and its ability to impact this axis. This bacterial strain that has been studied for decades for its role in gut and immune balance, is now, increasingly, studied for its potential role in supporting cognitive and emotional wellbeing. Most of the research into its effects on cognition have been conducted in just the last six years, but have maintained the high standards of the past, as most of these studies are RCTs.

A New Frontier of Research

The connection between gut bacteria and the brain is one of the fastest-growing areas in human health science, and LGG has been at the centre of many of the most interesting discoveries.

Across several studies adults taking LGG daily were found to experience improvements in cognitive impairment, along with measurable changes in their gut microbiome and immune markers, not to mention a decrease in inflammatory markers.

This promising new area of research suggests that perhaps LGG has a very real role to play in the management of the gut-brain axis and could constitute a beneficial option in natural approaches to boosting cognition.

Memory and Cognitive Function

In a recent double blind control study, adults with objective “cognitive impairment” who took LGG showed a larger improvement in total cognition score than the impaired placebo group, with higher scoring in learning and memory tests. 

Researchers found that participants taking LGG also had lower levels of inflammatory markers in their blood, as well as a greater abundance in certain species of microbe in the gut. Both of these criteria have been linked to cognitive performance in the past, suggesting that LGG may have a role to play in benefiting cognition.

In one such study, scientists measured participants’ gut bacteria before and after the trial and found that LGG increased bacterial populations of other bacteria, leading to greater abundance in the digestive tract. This suggests that by encouraging abundance and diversity in the gut microbiome, LGG can have the capability to help keep the gut’s microbial community balanced.

Gut–Brain Communication in Action

While researchers are still uncovering the exact mechanisms, the emerging picture is that LGG interacts with the body in several ways that may help maintain a healthy gut–brain connection:

-       Supporting a balanced gut microbiome, which in turn influences mood and cognition

-       Reducing systemic inflammation, which can interfere with brain signalling

-       Improving gut barrier function, which helps maintain stable communication between the gut and the nervous system

These findings are especially promising because they come from multiple independent trials, all conducted under the rigorous, high clinical standards we’ve come to expect from this microbe.

LGG and ADHD - An Emerging Science

One new and interesting area of research is the effects that LGG have on ADHD (Attention Deficit/Hyperactivity Disorder). A recent double blind RCT has explored the effects that LGG supplementation may have on the symptoms and severity of ADHD in children, specifically children aged between 4 – 17 years old.

These children were asked to rate their quality of life after 3 months of taking either LGG or a placebo, using the Paediatric Quality of Life Inventory measuring system. This is a self-report system that measures physical, social, emotional, and school functioning, and is widely respected in the world of paediatric psychology as a benchmark in quality-of-life measurement.

The results this study turned up were striking: the participants in the study showed a significant improvement in Quality of Life, an improvement that was not reported by observers, but by the participants themselves. 

These are early results, with this being a pilot study, and the study revolved around the participants themselves reporting how they felt their quality of life had been changed in the context of their ADHD. However, the use of a respected metric in quality of life, as well as a clear improvement in the LGG group, suggests that this may be a very promising area of research! The authors of the study themselves recommended a longer follow up trial with a larger group to help us explore these exciting findings, demonstrating that whilst it may be too early to draw a clear conclusion on the benefits LGG has on ADHD, it is certainly a promising area of research worth of further study.

Why this means for you

Although the gut–brain axis field is still relatively new, the quality and consistency of the research on LGG have made it one of the most closely followed bacterial strains in this area.

In just the last few years, studies have shown measurable improvements in:

-       Memory and attention.

-       Cognitive impairment

-       Markers of inflammation and neurotransmitter balance.

-       Possible quality of life improvement in ADHD children

All without any increase in side effects or safety concerns!

In summary

The research into how LGG can impact the Gut-Brain axis is an exciting new chapter in the ever growing body of scientific research surrounding this fascinating microbe.

While this area of science is still emerging, the results from recent human studies are consistently positive, showing that LGG can help the body maintain a healthy, communicative link between the gut and the mind.

It’s a field that’s evolving rapidly, with new research and studies conducted all the time, and if the research of the last 30 years is anything to go by, the future will bring more encouraging insight into the amazing things this microbe can really do.  

Digestive Comfort and Irritable Bowel Syndrome

For many people, maintaining digestive comfort can be an ongoing challenge. Bloating, irregular bowel movements, and occasional cramping are all signs that the gut may be struggling to stay balanced.

Lactobacillus rhamnosus GG (LGG) has been one of the most widely studied bacterial strains for supporting gut balance and digestive stability. Over the years, scientists have explored its potential to help maintain comfort in people with sensitive digestive systems, including those diagnosed with irritable bowel syndrome (IBS), to better understand how LGG might modulate symptoms. As ever, most of these studies are high quality RCT’s, we’d expect nothing less.

What the studies have shown

Early insights

One of the earliest investigations into LGG’s role in digestive balance came from researchers in Europe in the early 1990s.

In this trial, adults with mild IBS-like symptoms took LGG daily for six weeks. The participants who received LGG reported fewer episodes of loose stools and cramping, while stool cultures confirmed that LGG survived its journey through the digestive tract, an important sign that the bacteria can reach and survive the full digestive system.

Modern clinical trials

More recent studies have explored LGG both alone and in combination with other well-studied bacterial species, focusing specifically on adults diagnosed with IBS.

In a 2018 double-blind, placebo-controlled trial involving 123 adults, those who took LGG daily for 12 weeks experienced a significant reduction in abdominal pain scores and more regular bowel movements compared with the placebo group.

It’s important to note that this study was conducted with participants taking supplements of both LGG and BB12 (Bifidobacterium Animalis subps. Lactis BB12), another well researched and promising microbe that we’re passionate about.

Blood tests in another similar study also showed lower levels of gut inflammation markers, demonstrating a reduction in IL-6 and TNF Alpha (inflammatory cytokines), suggesting a calmer, more stable intestinal environment. This is consistent with a lot of the research conducted into LGG’s effects on the immune environment and levels of IgA as well as reduction of inflammatory markers.    

Another clinical study published in 2011 found that people taking a supplement containing LGG among other bacteria for six weeks experienced less bloating and overall digestive discomfort than those taking placebo, supporting the idea that LGG can help maintain a steadier digestive rhythm in sensitive individuals.

Across all of these studies, participants tolerated LGG extremely well, with no increase in side effects compared with placebo, and subsequently no safety concerns.

The science behind it

Researchers believe that LGG works by helping the gut maintain a balanced community of bacteria and supporting the natural lining of the intestines and the mucosal barrier.

In people with IBS, this delicate balance can be easily disrupted, leading to irregular movements, bloating, and discomfort, and occasionally far more severe symptoms.

By promoting a more stable environment, LGG may help the gut stay calm by limiting inflammatory markers as one study has found, and function more smoothly.

Several trials have also measured immune markers and found that participants taking LGG showed lower levels of certain inflammatory signals related to immunity in their bloodstream, another strong sign of a more settled digestive system.

What this means for you

Over three decades of research, including multiple gold-standard human trials, suggest that Lactobacillus rhamnosus GG may play a valuable role in maintaining digestive comfort and supporting gut balance.

In adults with sensitive digestion or IBS, daily use of LGG at doses around 10 billion CFU per day has been associated with:

-       More regular bowel movements

-       Less bloating and cramping

-       Calmer, more stable digestion

-       Reduced intestinal inflammation markers

All achieved with excellent safety and tolerability, with no reported side effects!

Digestive Health While Travelling

For many people, travelling abroad can sometimes bring unwanted surprises; unfamiliar foods, new environments, and changes in local water can all affect digestive balance. Maintaining a settled gut while away from home is an important part of enjoying the journey.

Lactobacillus rhamnosus GG (LGG) has been studied extensively for its role in supporting digestive stability during travel, helping to maintain a balanced gut environment when exposed to new bacteria or dietary changes, and calming the symptoms when people have experienced them. As with the vast majority of research into LGG, health while travelling has been researched to the highest standards, with RCTs abound.

What the studies have shown

Fewer episodes of traveller’s digestive upset.

In one landmark clinical trial involving 756 Finnish travellers to southern Turkey, those who took LGG daily throughout their trip were found to have experienced serious digestive upset at a lower rate. The LGG group experienced diarrhoea at a rate of 41%, compared to 46.5% in the placebo group, indicating a trend that LGG may have a positive effect on preventing traveller’s diarrhoea.

Consistent findings in other parts of the world

It wasn’t just a Finnish study that had these results, similar results were seen in other clinical studies around the world.

In one large American study, 245 travellers visiting Mexico took LGG or a placebo for two weeks. Those who took LGG experienced traveller’s diarrhoea at a rate of 3.9% compared to the 7.4% of the placebo group. When taken in comparison, these results show that those on LGG were far less likely to suffer traveller’s diarrhoea. These results reinforce what the Finnish study had found, that LGG demonstrates the potential the help reduce the likelihood of digestive upset whilst travelling. 

Another study followed Danish travellers to Egypt, and supplemented them with a mixture of lactobacilli, including LGG. It found that only 43% of the probiotic group suffered TD, whilst 71% of the control group experienced it. Whilst a mix of lactobacilli, and not exclusively LGG was used, this does demonstrate this microbial family’s powerful ability to support the gut, and of course amongst lactobacilli, LGG can boast a breadth of scientific research that is hard to beat!  

The big picture – A meta-analysis

A meta-analysis was conducted in 2007 to pool the results of probiotic (including LGG) trials into traveller’s diarrhoea, helping to step away from any one study and look at the big picture, and the results were encouraging to say the least. The results found that across studies the risk of traveller’s diarrhoea was reduced by some 15% in those taking the probiotics.

Whilst this applies to other microbes as well as LGG, it does demonstrate the potential that these microbes can have to help keep the digestive system regulated and calm when abroad.

The science behind it

Researchers believe LGG helps the gut stay stable by supporting the natural balance of bacteria that line the intestines.

When travelling, the digestive system is suddenly exposed to new microbial environments and foods, which can disrupt that balance, introduce new bacteria, or encourage existing bacteria to grow faster than they usually would.

LGG appears to strengthen the gut’s natural defences and help maintain microbial stability during these periods of change, making the digestive system more resilient to sudden changes, and helping to reduce their impact.

In studies where stool samples were collected, LGG was shown to survive its journey through the stomach and temporarily colonise the gut, providing a supportive presence anywhere in the digestive system as opposed to only the earliest sections. This is important as it shows that LGG, once in your gut, can survive all the way through, ensuring that it can reach wherever it is needed most.

What this means for you

Across multiple gold-standard human trials, Lactobacillus rhamnosus GG has been shown to help maintain a stable and balanced digestive system during travel, reducing the likelihood of digestive upset and shortening its duration when it does occur.

Key findings from these studies include:

-       Consistent results that show LGG reduced incidence of TD

-       An ability to survive the full digestive process

-       No safety concerns or adverse effects

In short

Whether you’re travelling for business, adventure, or relaxation, Lactobacillus rhamnosus GG has been scientifically studied in multiple studies in the context of travel-related digestive challenges. Travelling can be an amazing experience, empowering us to explore new places, cultures, foods and experiences, and through all of this LGG has shown great potential to keep the digestive system balanced and in tune.

Other Areas of Study

There are many other areas and contexts in which LGG has been studied, and so many in which it has shown interesting and often positive results. We could talk all day about the fascinating results of these scientific papers, but here’s just a couple worth mentioning.

H.Pylori Treatment

LGG has been the subject of a few studies into its effects in treatments for H. Pylori infection. H. Pylori is a bacterium commonly found in the stomach that can overgrow, causing digestive problems and often more severe symptoms, and requiring treatment with antibiotics.

A few studies have researched LGG’s effects alongside antibiotics in treating H. Pylori with promising results. One study found that those who took the LGG experienced far fewer side effects than those who didn’t, with bloating, diarrhoea and taste disturbance all reduced.

This promising result helps to highlight LGG’s ability to calm the digestive system and bring balance, and suggests that pairing it with antibiotics can make for a very effective team.

Early Dental Health

An interesting RCT study, with a large group of 594 children, was conducted into the use of LGG in the prevention of dental caries in early life. Two groups of children drank milk every day, one with LGG, one without, for a period of 7 months, and the results were striking.

The LGG cohort of children were found to have considerably lower incidence of dental caries, as well as a reduction in Mutans Streptococci, a bacterium often associated with dental health problems.

This encouraging research suggests that LGG can help not only in the gut, but in the earlier stages of the digestive system as well!

Liver Health

A final study worth mentioning is one in which the benefits of LGG supplementation were explored in patients diagnosed with Cirrhosis, a condition of long-term scarring on the liver, and MHE (minimal hepatic encephalopathy). Patients in this group were either given LGG or a placebo, and the results were very interesting indeed.

The LGG cohort had a significant reduction in endotoxemia, as well as reduced count of TNF Alpha, an inflammatory cytokine. Not only this, but they also demonstrated a more balanced gut microbiome, with numbers of overgrown bacteria dropping and numbers of healthy but underrepresented bacteria growing. On top of this the LGG did not have any negative side effects whatsoever.

Whilst this study looks at one very specific group of people, it helps to underline the point, that this powerful little microbe shows potential to help us when our bodies need it the most.

Safe and Studied – A Powerful Microbe in Review.

Lactobacillus rhamnosus GG (LGG) has been researched for over three decades and is recognised globally for its excellent safety profile. It is a non-pathogenic, non-toxic, and well-characterised bacterial strain that has been studied in hundreds of human clinical trials, involving participants of all ages, ranging from newborns to older adults.

LGG has been officially recognised as safe for human consumption by multiple leading health authorities around the world, including the FDA in the United States, the EFSA in Europe, Health Canada and the WHO (World Health Organisation).

Not only this, but in fact some of the most respected health and dietetic organisations around the world have recommended it’s use in a variety of contexts. This includes the British Dietetic Association, The Royal Australian College of General Practitioners, The ESPGHAN (European Society for Paediatric Gastroenterology, Hepatology and Nutrition), and the BSPGHAN (British version). With such a strong body of high standard research behind it, it’s no wonder that medical institutions and organisations such as these are taking note! The recommendations these bodies make varies from general guidance through to recommended use alongside antibiotics.

Across decades of research, LGG has consistently demonstrated no pathogenicity, no toxin production, and no antibiotic resistance concerns, cementing its reputation as not only very promising in its effectiveness, but completely safe as well.

It is used worldwide in both dietary supplements and functional foods, and its safety has been reaffirmed repeatedly through long-term clinical use and official scientific evaluation.

It is for all of these reasons, and all of the evidence in this article, that we are so proud to count LGG as a microbe we have the privilege to work with. Even though it covers a lot of areas, this article only scratches the surface of the vast body of research behind this microbe, and it’s for that reason that we’re so excited about the good it can do!

The majority of these studies used fairly high concentrations, with the most common dose being 10BN CFU (Colony Forming Units) per day. It’s for that reason we chose to make our LGG supplement 12BN CFU, ensuring that on a full daily serving, the person taking it will get the same if not a higher count of bacteria as the participants in the studies that have shown such great potential for this microbe.

We’re not just encouraged, but greatly enthusiastic about the promising body of scientific literature surrounding LGG, and we for one can’t wait to see amazing new insights future studies will bring!

Disclaimer – An Important Note

All information provided on this page is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. The studies referenced in this article were conducted independently by a wide variety of individuals and organisations around the world, and are not affiliated with, conducted by, funded by, or conducted for, BetterGuts or Strain Supplements Ltd.

Always consult a qualified healthcare professional before starting any new supplement, especially if starting it alongside existing medication.

References – The Science Itself.

1. Digestive & Antibiotic-Associated Diarrhoea

1. Guandalini, S., Pensabene, L., Zikri, M.A., et al. (2000) Lactobacillus GG administered in oral rehydration solution to children with acute diarrhea: a multicenter European trial. Journal of Pediatric Gastroenterology and Nutrition, 30(1), 54–60. https://pubmed.ncbi.nlm.nih.gov/10630441
2. Szajewska, H. & Kolodziej, M. (2015) Systematic review with meta-analysis: Lactobacillus rhamnosus GG in the prevention of antibiotic-associated diarrhoea in children and adults. Alimentary Pharmacology & Therapeutics, 42(10), 1149–1157. https://pubmed.ncbi.nlm.nih.gov/26365388
3. Vanderhoof, J.A., Whitney, D.B., Antonson, D.L., et al. (1999) Lactobacillus GG in the prevention of antibiotic-associated diarrhoea in children. Journal of Pediatrics, 135(5), 564–568. https://pubmed.ncbi.nlm.nih.gov/10547242
4. Arvola, T., Laiho, K., Torkkeli, S., et al. (1999) Prophylactic Lactobacillus GG reduces antibiotic-associated diarrhoea in children with respiratory infections: a randomized study. Pediatrics, 104(5), e64. https://pubmed.ncbi.nlm.nih.gov/10545585

2. Acute Gastroenteritis

5. Szajewska, H., Skórka, A. & Dylag, M. (2001) Meta-analysis: Lactobacillus rhamnosus GG for treating acute gastroenteritis in children. Journal of Pediatric Gastroenterology and Nutrition, 33(1), 38–43. https://pubmed.ncbi.nlm.nih.gov/11479404
6. Aggarwal, S., Upadhyay, A., Shah, D., Teotia, N., Agarwal, A. and Jaiswal, V. (2014) ‘Lactobacillus GG for treatment of acute childhood diarrhoea: an open labelled, randomized controlled trial’, Indian Journal of Medical Research, 139(3), pp. 379–385. Available at: https://pubmed.ncbi.nlm.nih.gov/24820831/

7.     Guarino, A., Canani, R.B., Spagnuolo, M.I., Albano, F. and Di Benedetto, L. (1997) ‘Oral bacterial therapy reduces the duration of symptoms and of viral excretion in children with mild diarrhea’, Journal of Pediatric Gastroenterology and Nutrition, 25(5), pp. 516–519. Available at: https://pubmed.ncbi.nlm.nih.gov/9360205/ 

8. Rautanen, T., Isolauri, E. & Salo, E. (1998) Lactobacillus casei strain GG in the treatment of acute rotavirus diarrhoea in children. Scandinavian Journal of Infectious Diseases, 30(5), 489–493. https://pubmed.ncbi.nlm.nih.gov/9814501
9. Huang, J.S., Bousvaros, A., Lee, J.W., et al. (2002) Efficacy of probiotic Lactobacillus GG in treatment of acute watery diarrhoea: a meta-analysis. Journal of Pediatrics, 140(4), 528–532. https://pubmed.ncbi.nlm.nih.gov/12006958

3. Immune Interaction & Infection

10.  Kumpu, M., Kekkonen, R.A., Korpela, R., et al. (2012) Effect of Lactobacillus rhamnosus GG on respiratory tract infections in children: a randomized trial. European Journal of Clinical Nutrition, 66(9), 1021–1026. https://pubmed.ncbi.nlm.nih.gov/22824830

11.  Hatakka, K., Savilahti, E., Pönkä, A., Meurman, J.H., Poussa, T., Näse, L., Saxelin, M. and Korpela, R. (2001) ‘Effect of long term consumption of probiotic milk on infections in children attending day care centres: double blind, randomised trial’, BMJ, 322(7298), p. 1327. Available at: https://pubmed.ncbi.nlm.nih.gov/11387176/

12. Hojsak, I., Abdović, S., Szajewska, H., et al. (2010) Lactobacillus GG in the prevention of nosocomial gastrointestinal and respiratory tract infections. Clinical Nutrition, 29(4), 483–488. https://pubmed.ncbi.nlm.nih.gov/20074854
13. Kumpu, M., Kekkonen, R.A., Järvenpää, S., et al. (2013) Lactobacillus rhamnosus GG modulates immune responses in healthy adults: a randomized, placebo-controlled trial.* British Journal of Nutrition, 110(5), 858–866. https://pubmed.ncbi.nlm.nih.gov/23388074

14.  Segers ME, Lebeer S. Towards a better understanding of Lactobacillus rhamnosus GG--host interactions. Microb Cell Fact. 2014 Aug 29;13 Suppl 1(Suppl 1):S7. doi: 10.1186/1475-2859-13-S1-S7. Epub 2014 Aug 29. PMID: 25186587; PMCID: PMC4155824. https://pmc.ncbi.nlm.nih.gov/articles/PMC4155824/

4. Infant & Early-Life Development

15.  Kalliomäki, M., Salminen, S., Arvilommi, H., et al. (2001) Probiotics in primary prevention of atopic disease: a randomized placebo-controlled trial. The Lancet, 357(9262), 1076–1079. https://pubmed.ncbi.nlm.nih.gov/11297958

16. Kalliomäki, M., Salminen, S., Poussa, T., et al. (2003) Sustained effect of probiotic on atopic disease: follow-up at four years. The Lancet, 361(9372), 1869–1871. https://pubmed.ncbi.nlm.nih.gov/12788576
17. Wickens, K., Black, P.N., Stanley, T.V., et al. (2008) Probiotic Lactobacillus rhamnosus HN001 and allergic disease in infants: a randomized trial. Clinical & Experimental Allergy, 38(9), 1391–1399. https://pubmed.ncbi.nlm.nih.gov/18513380

18.  Rautava, S., Kalliomäki, M. and Isolauri, E. (2002) ‘Probiotics during pregnancy and breast-feeding might confer immunomodulatory protection against atopic disease in the infant’, Journal of Allergy and Clinical Immunology, 109(1), pp. 119–121. Available at: https://pubmed.ncbi.nlm.nih.gov/11799376

5. Skin & Allergy Research (Adults)

14. Laursen, R.P., Larnkjær, A., Ritz, C., et al. (2021) Probiotic effects on allergic disease: systematic review. Clinical & Translational Allergy, 11(7), e12071. https://pubmed.ncbi.nlm.nih.gov/34385933
15. Kalliomäki, M., Antoine, J.M., Herz, U., et al. (2010) Guidelines for the evaluation of probiotics in food. FAO/WHO Expert Consultation Report. https://www.fao.org/3/a0512e/a0512e.pdf

16.  De Boeck, I., Spacova, I., Cauwenberghs, E., et al. (2025) ‘Lacticaseibacillus rhamnosus GG in a chewable colonizes the nose and facilitates local immune benefits in allergic rhinoconjunctivitis patients’, Microbiology Spectrum, 13(10), e00773-25. doi: 10.1128/spectrum.00773-25. Available at: https://pubmed.ncbi.nlm.nih.gov/40891819/ 

17.  Piirainen, L., Haahtela, S., Helin, T., Korpela, R., Haahtela, T. and Vaarala, O. (2008) ‘Effect of Lactobacillus rhamnosus GG on rBet v1 and rMal d1 specific IgA in the saliva of patients with birch pollen allergy’, Annals of Allergy, Asthma & Immunology, 100(4), pp. 338–342. doi: 10.1016/S1081-1206(10)60596-0. Available at: https://pubmed.ncbi.nlm.nih.gov/18450119/  

6. Gut–Brain Axis

17. Sanborn, V., Azcarate-Peril, M.A. & Gunstad, J. (2020) Randomized clinical trial examining the effects of Lactobacillus rhamnosus GG on cognitive functioning in older adults. Neuropsychiatric Disease and Treatment, 16, 2765–2777. https://pmc.ncbi.nlm.nih.gov/articles/PMC7671471
18. Aljumaah, M.R., et al. (2022) The gut microbiome, mild cognitive impairment, and probiotics: a randomized controlled trial. Clinical Nutrition, 41(12), 2690–2700. https://pubmed.ncbi.nlm.nih.gov/36228569

19.  Bajaj, J.S., Heuman, D.M., Hylemon, P.B., et al. (2014) ‘Randomized clinical trial: Lactobacillus GG modulates gut microbiome, metabolome and endotoxemia in patients with cirrhosis’, Alimentary Pharmacology & Therapeutics, 39(10), pp. 1113–1125. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3989370/

20. Lew, L.C., Hor, Y.Y., Yusoff, N.A.A., et al. (2019) Probiotic supplementation improves cognitive and psychological performance in healthy elderly subjects. Frontiers in Aging Neuroscience, 11, 129. Available at: https://doi.org/10.3389/fnagi.2019.00129

21.  Kumperscak, H.G., Gricar, A., Ülen, I. & Micetic-Turk, D. (2020) ‘A pilot randomized control trial with the probiotic strain Lactobacillus rhamnosus GG (LGG) in ADHD: Children and adolescents report better health-related quality of life’, Frontiers in Psychiatry, 11:181. Available at: https://www.frontiersin.org/articles/10.3389/fpsyt.2020.00181/full

7. Irritable Bowel Syndrome (IBS)

22. Goldin, B.R., Gorbach, S.L., Saxelin, M., et al. (1992) Survival of Lactobacillus rhamnosus GG in human gastrointestinal tract. European Journal of Clinical Nutrition, 46(Suppl 4), S93–S99. https://pubmed.ncbi.nlm.nih.gov/1425482
23. Zeng, J., Li, Y.Q., Zeng, Y.S., et al. (2018) Clinical trial of probiotics containing Lactobacillus rhamnosus GG and Bifidobacterium lactis BB-12 in irritable bowel syndrome. Beneficial Microbes, 9(4), 575–584. https://pubmed.ncbi.nlm.nih.gov/29745792
24. Guglielmetti, S., Mora, D., Gschwender, M., et al. (2011) Randomized clinical trial: probiotics and irritable bowel syndrome symptoms. World Journal of Gastroenterology, 17(34), 5115–5121. https://pubmed.ncbi.nlm.nih.gov/21987628

25.  O’Mahony, L., McCarthy, J., Kelly, P., Hurley, G., Luo, F., Chen, K., O’Sullivan, G.C., Kiely, B., Collins, J.K., Shanahan, F. and Quigley, E.M.M. (2005) ‘Lactobacillus and Bifidobacterium in irritable bowel syndrome: symptom responses and relationship to cytokine profiles’, Gastroenterology, 128(3), pp. 541–551. Available at: https://pubmed.ncbi.nlm.nih.gov/15765388/

26.  O’Mahony, L., O’Mahony, S., Quigley, E.M.M., Shanahan, F. and Collins, J.K. (2008) ‘Immune modulation by probiotic bacteria in the management of irritable bowel syndrome’, British Journal of Nutrition, 99(2), pp. 273–281. Available at: https://pubmed.ncbi.nlm.nih.gov/17697415/

8. Traveller’s Digestive Health

25. Oksanen, P., Salminen, S., Saxelin, M., et al. (1990) *Prevention of traveller’s diarrhoea by Lactobacillus GG. Annals of Medicine, 22(1), 53–56. https://pubmed.ncbi.nlm.nih.gov/2180910
26. Hilton, E., Kolakowski, P., Singer, C., et al. (1992) Lactobacillus GG and traveller’s diarrhoea: a randomized double-blind study. Journal of Travel Medicine, 1(4), 206–209. https://pubmed.ncbi.nlm.nih.gov/9818863
27. Black, F.T., Andersen, P.L., Orskov, J., et al. (1989) Prophylactic efficacy of Lactobacillus GG on traveller’s diarrhoea. Digestive Diseases and Sciences, 34(9), 1397–1400. https://pubmed.ncbi.nlm.nih.gov/2672223
28. McFarland, L.V. (2007) ‘Meta-analysis of probiotics for the prevention of traveller’s diarrhoea’, Travel Medicine and Infectious Disease, 5(2), pp. 97–105. doi:10.1016/j.tmaid.2005.10.003. Available at: https://pubmed.ncbi.nlm.nih.gov/17298915/

9. Other Areas of Study

29.Armuzzi, A. et al. (2001) ‘Effect of Lactobacillus GG supplementation on antibiotic-associated gastrointestinal side effects during Helicobacter pylori eradication therapy: a pilot study’, Digestion, 63(1), pp. 1–7. Available at: https://pubmed.ncbi.nlm.nih.gov/11173893/ 

30.  Näse, L., Hatakka, K., Savilahti, E., Saxelin, M., Pönkä, A., Poussa, T., Korpela, R. and Meurman, J.H. (2001) ‘Effect of long-term consumption of a probiotic bacterium, Lactobacillus rhamnosus GG, in milk on dental caries and caries risk in children’, Caries Research, 35(6), pp. 412–420. doi:10.1159/000047484. Available at: https://pubmed.ncbi.nlm.nih.gov/11799281/ 

31.  Bajaj, J.S., Heuman, D.M., Hylemon, P.B., et al. (2014) ‘Randomised clinical trial: Lactobacillus GG modulates gut microbiome, metabolome and endotoxemia in patients with cirrhosis’, Alimentary Pharmacology & Therapeutics, 39(10), pp. 1113–1125. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3989370/

10. Safety and Regulatory Recognition

31. U.S. Food and Drug Administration (FDA) (2020) Generally Recognized as Safe (GRAS) Notice Inventory: Lactobacillus rhamnosus GG (GRN No. 000240). https://www.fda.gov/food/generally-recognized-safe-gras/gras-notice-inventory
32. European Food Safety Authority (EFSA) (2023) Qualified Presumption of Safety (QPS) list of microorganisms with safety status. EFSA Journal, 21(5): 7809. https://www.efsa.europa.eu/en/topics/topic/qualified-presumption-safety-qps
33. Health Canada (2011) Natural Health Products Ingredients Database: Lactobacillus rhamnosus GG. https://health-products.canada.ca/nhpid-bdipsn
34. FAO/WHO (2002) Guidelines for the Evaluation of Probiotics in Food. Joint FAO/WHO Expert Consultation Report, London, Ontario. https://www.fao.org/3/a0512e/a0512e.pdf