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Lactobacillus rhamnosus GG: A Probiotic for All Ages

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The benefits of L. rhamnosus GG for gut health and immunity

Today’s probiotic story began in 1983, when Drs. Sherwood Gorbach and Barry Goldin, colleagues at Tufts University, were poring over stool specimens from healthy adults – a task few of us would envy. They managed to isolate “a strain of bacteria of a Lactobacillus species in which the bacteria have avid adherence to intestinal cells, are able to survive at low pH, and produce large amounts of lactic acid.”

The strain was named “Lactobacillus rhamnosus Gorbach-Goldin”, wherein Lactobacillus refers to the bacterial genus, rhamnosus refers to the species, and Gorbach-Goldin refers to the discovers. Now known as Lactobacillus rhamnosus GG, it has become the most extensively-studied probiotic strain of all time.[1],[2],[3] This strain is still benefiting human health, 35 years later, and our understanding of its features and benefits continues to grow.

L. rhamnosus GG has been shown to colonize the gut when it is consumed regularly,[4] and to modulate the functions of epithelial, immune, and nerve cells that reside within the gastrointestinal tract.[5],[6],[7] While it is in residence, L. rhamnosus GG churns out lactic acid, bioactive peptides, proteins, and amino acids. These soluble mediators have been shown to support intestinal function, reduce infections and inflammation, and assist with immunity throughout the body.[8],[9],[10],[11]

Infection-fighting properties of L. rhamnosus GG

Extensive research has shown that L. rhamnosus GG can inhibit the growth of bacterial pathogens.

Extensive research has shown that L. rhamnosus GG can inhibit the growth of bacterial pathogens, thereby reducing the risk of harmful infections in the gastrointestinal tract.[12],[13] It has been shown to inhibit Salmonella, Listeria, Escherichia coli, and other bacteria that cause serious foodborne illnesses.[14],[15],[16],[17]

L. rhamnosus GG also inhibits many opportunistic pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium difficile, and Candida spp., all of which can cause systemic infections.[15],[18],[19],[20],[21],[22] Opportunistic pathogens are a particular problem for individuals who are immunocompromised.

Rotavirus is a very contagious virus that causes diarrhea in infants and children.[23],[24],[25] The consumption of L. rhamnosus GG has been shown to reduce the duration and severity of rotavirus infection, especially at doses greater than 10 billion colony-forming units (CFU) per day.[26],[27] A meta-analysis of 19 clinical trials concluded that high-dose L. rhamnosus GG therapy reduces the duration of diarrhea and the stool number per day, especially if supplementation is started at the early stage of infection.[27]

The antimicrobial properties of L. rhamnosus GG may also help the body fight off respiratory infections. In a placebo-controlled trial, 742 children who were hospitalized, and therefore susceptible to opportunistic infections, were randomly allocated to receive L. rhamnosus GG (1 billion CFU in 100 mL of a fermented milk product daily).[12] As compared to the placebo, L. rhamnosus GG supplementation reduced the risk for hospital-acquired gastrointestinal and respiratory tract infections by 60%.

Another study, done in healthy preschool children, showed that daily supplementation with L. rhamnosus GG for seven months over the winter season reduced the risk of bacterial infections for up to three years after the trial, as indicated by reduced antibiotic use during that period.[13]

Over the long term, L. rhamnosus GG may even combat bacteria that produce cavities in teeth.[28] In one study, 594 children received either regular milk or milk containing L. rhamnosus GG for five days per week.[29] After seven months, children in the probiotic group had fewer cavities and a lower number of potentially harmful bacteria in the mouth than children in the milk-only group.

L. rhamnosus GG helps alleviate leaky gut

Clinical studies have shown that L. rhamnosus GG supplementation may ameliorate symptoms of irritable bowel.

Leaky gut can occur as a result of environmental exposures, infections, medications, and many other factors.[30],[31],[32] This condition allows troublesome bacteria, toxins, incompletely digested food, and metabolic waste products to pass from the digestive tract into the body, triggering systemic inflammation.

L. rhamnosus GG has been shown to improve the survival of gut epithelial cells exposed to damaging agents, thereby reducing leaky gut.[33],[34] It exerts this function by secreting bioactive proteins with cell-protective effects.[10],[17],[35],[36],[37],[38] In animal models, L. rhamnosus GG has been shown to alleviate leaky gut resulting from gastrointestinal infections,[17],[24],[34],[39] alcohol use,[40],[41],[42] gluten toxicity,[43] and radiation treatments.[44]

Leaky gut is an important factor in the pathology of irritable bowel syndrome (IBS).[45],[46] Scientists have shown that the medium (solution from its culture) collected from L. rhamnosus GG cultures can prevent the increase in leaky gut associated with this condition and can alleviate visceral pain hypersensitivity in animal models.[38],[47]

Consistent with these findings, clinical studies have shown that L. rhamnosus GG supplementation may ameliorate symptoms of IBS in children and adults.[48],[49],[50] In children aged 4 to18 who were diagnosed with IBS, a reduction in pain scores was seen after four week’s supplementation with L. rhamnosus GG at a dose of approximately 20 billion CFU/day.[51] A significant reduction in symptoms also was observed in adults with IBS (especially the diarrhea-predominant type) who were supplemented with L. rhamnosus GG (12 billion CFU daily for six weeks).[50]

L. rhamnosus GG can reduce the risk of allergies

L. rhamnosus GG supplementation was shown to relieve gastrointestinal symptoms in children with cow’s milk allergy.

Food allergy affects nearly 8% of children and 5% of adults.[52],[53] The risk of allergies is influenced by many factors, including heredity (allergy in one or both parents), duration of pregnancy, mode of birth (vaginal or cesarean), and breastfeeding or formula feeding.[54],[55],[56],[57]

Studies have shown that the risk of developing childhood allergies is influenced by the gut microbiota in infancy.[58],[59],[60] Recent studies have shown that a relative absence of lactobacilli species (L. casei, L. paracasei, and L. rhamnosus) in infant fecal samples collected between one week and two months of age was associated with the development of allergy,[60] and that colonization with these species seems to decrease the risk for allergy at five years of age, regardless of allergic heredity.[61] Supplementation with L. rhamnosus GG may help restore more normal levels of lactobacilli and other friendly bacteria.[13],[62],[63]

For infants and children with cow’s milk allergy (CMA), the use of a hypoallergenic formula (extensively hydrolyzed casein formula; EHCF), supplemented with L. rhamnosus GG, has been shown to accelerate the acquisition of immune tolerance in infants compared to EHCF alone.[63],[64],[65],[66] After 12 months of continuous supplementation, the proportion of children acquiring immune tolerance to cow’s milk was significantly higher in the group receiving the probiotic formula (79%), compared to EHCF alone (44%); soy formula (24%); and the amino acid-based formula (18%).[63]

In long-term studies, supplementation with EHCF containing L. rhamnosus GG was confirmed to reduce the incidence of CMA and eczema (an allergic skin condition).[67] L. rhamnosus GG supplementation was also shown to relieve gastrointestinal symptoms in children with CMA.[68] Studies in animal models further suggest that L. rhamnosus GG may protect against allergic airway inflammation.[69],[70]

L. rhamnosus and vaccine responses

L. rhamnosus GG promotes Th1-type immune responses, which are associated with protection against infections and with improved vaccine efficacy.[71],[72],[73],[74] In a placebo-controlled study of influenza vaccination, 84% of those who consumed L. rhamnosus GG developed a protective titer for the H3N2 strain versus only 55% of those in the placebo group.[75] The L. rhamnosus GG was consumed at a dose of 20 billion CFU daily for 28 days, beginning on the day of vaccination.

In another placebo-controlled trial, supplementation with L. rhamnosus GG (10 billion CFU/day) for five weeks (one week prior to vaccination, and four weeks afterwards) greatly increased the response to poliovirus vaccine.[76] The maximum increase after immunization in the probiotic group was about 2-fold or 4-fold higher, respectively, for poliovirus-neutralizing antibody titers and immunoglobulin G (IgG) levels in volunteers consuming probiotics instead of placebo.

Can L. rhamnosus GG influence brain aging?

As time goes on, we continue to learn more and more about the systemwide effects of L. rhamnosus GG, which clearly extend beyond the gut. For example, the gut microbiota may be an important contributor to cognitive aging,[77] and probiotics can influence this process.[78] In a double-blind, placebo-controlled, randomized clinical trial of 145 adults aged 52 to 75, supplementation with L. rhamnosus GG (20 billion CFU/day for 90 days) was shown to improve cognitive performance in individuals with cognitive impairment.[79] The authors of this intriguing study conclude that supplementation with this probiotic may be a novel method for protecting cognitive health with increasing age.


In sum, L. rhamnosus GG is one of the most versatile probiotics known to humankind. It is often used in combination with other probiotic species, but it has many positive health effects on its own. It can help reduce the risk of opportunistic and foodborne infections (and the diarrhea that results); ameliorate leaky gut and IBS; promote the development of tolerance to allergens in children; and improve immunity and vaccine responses in adults. It’s worth considering as a probiotic that is suitable for all ages.

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