Lactobacillus rhamnosus

Written by: Kari Raman, PharmD, RPh
Published March 20, 2023

Lactobacillus rhamnosus is a type of bacteria that naturally lives in the human body, predominantly in the gut. It is a popular probiotic supplement often recommended for various health benefits. As a pharmacist, I frequently receive questions about L. rhamnosus and its potential health benefits from patients looking to learn more about probiotics. (For more information on probiotic naming conventions, visit our probiotic species page, but it’s also called L. rhamnosus in the medical community.)

It’s in the genus Lactobacillus, which is a type of bacteria that has a lot of uses in probiotics, several species of which live in healthy human guts, and if in a lot of fermented foods. 

Luckily, there is an abundance of clinical studies on Lactobacillus rhamnosus, so I’ve got lots to talk about!

Antibiotics and L. rhamnosus

There is some pretty great research around L. rhamnosus and antibiotics. A very common question I get at the pharmacy is when patients are picking up an antibiotic prescription – sometimes antibiotics can cause diarrhea. Since they are a medicine that kills bacteria, the bacteria in your gut also can … well, killed too. So this can cause an imbalance in the microbiome, and can lead to digestive issues. L. rhamnosus has some promising research that it might help fight this off. Read my article on how to take probiotics with antibiotics here.

What does Lactobacillus rhamnosus do?

Clinical trials and research studies reveal evidence supporting the potential benefits of Lactobacillus rhamnosus as a probiotic. These benefits may include enhancing immune function, promoting gut health, reducing IBS symptoms, preventing and treating diarrhea, and more. In my reviews of the medical research, L. rhamnosus is one of the probiotics that appears, in my opinion, to be able to actually help reduce the length of a bout of diarrhea.

As always, I want to remind everyone that it’s important to note that results can vary due to factors such as strain, dosage, and individuals may have different responses based on a whole host of factors, many of which, to be totally honest, medicine doesn’t really understand quite yet. 

While studies may show that L. rhamnosus is effective for certain conditions, it may not necessarily benefit every individual. Always consult your primary care physician if you experience any serious health issues, including recurring diarrhea.

Clinical trial summary

  1. Promoting gut health: L. rhamnosus can contribute to a healthy balance of gut bacteria by competing with and inhibiting the growth of harmful bacteria. It produces substances such as lactic acid that create an unfavorable environment for pathogenic bacteria, promoting a healthier gut microbiome. Since healthy human digestive systems already/typically have this bacteria living in them, it makes sense that it would be a popular probiotic.
  2. Enhancing immune function: It’s crazy to think that your gut can impact your immune system, but some studies indicate that L. rhamnosus may stimulate the immune system by interacting with immune cells and enhancing their activity. This can help the body better respond to infections and other challenges. The most impressive study I referenced showed that it might boost immune function in the respiratory system! Pretty cool, when you think about it.
  3. Reducing anxiety: There is emerging evidence that L. rhamnosus may have potential benefits for mental health, particularly in reducing anxiety. Some studies have shown that this probiotic may help modulate the stress response and improve anxiety symptoms, and there are a number of studies in rodents showing that they can help. I wouldn’t call this definitive research though, and so if you are experiencing any mental health issues you should definitely see your doctor. 
  4. Alleviating diarrhea: L. rhamnosus has been shown to help reduce the duration and severity of diarrhea, especially in cases of antibiotic-associated diarrhea and traveler’s diarrhea. I feel like this is an area where it’s been well studied and seems to have some legitimate health benefits.
  5. Improving brain function: I’ve even seen a well designed clinical trial that suggests that it can help older adults have higher cognitive function. I haven’t actually seen that many studies on the impacts of probiotics on brain function, so this is a pretty interesting study. But, it only had ~150 people in it, so I’d need to see more studies on a greater number of folks to really feel comfortable. This was a double blind, placebo controlled study, so that is the gold standard in medical research. Interesting stuff, and it’s super interesting to think about how your gut impacts your brain. 

Specific conditions

Some people are very excited about what probiotics can do, and talk about different ones helping with conditions where I haven’t seen as much medical evidence (at least yet).

This bacteria is no exception. I’m not sure I’m totally sold on it helping with a few issues that others seem to be very excited about.

Lactobacillus rhamnosus and eczema

While some websites are suggesting that L. rhamnosus may help improve eczema symptoms, it’s important to approach these findings with a degree of skepticism. The evidence supporting its effectiveness for eczema is not as strong as for other health benefits, and the results have been inconsistent across various studies. Some research has shown little to no improvement in eczema symptoms when using L. rhamnosus as a probiotic supplement. Additionally, the mechanisms through which L. rhamnosus might influence eczema are not yet fully understood, and further research is needed to establish a clear connection. As with any probiotic, individual responses can vary widely, and it’s crucial to consider the overall body of evidence before drawing conclusions about the efficacy of L. rhamnosus for treating eczema. So I’m not fully bought into it helping with eczema, although I’d be excited to review research that suggests otherwise.

Does L. rhamnosus help with lactose intolerance

It makes sense that a bacteria that digests lactose would help reduce the symptoms of lactose intolerance. However, clinical trials on L. rhamnosus and lactose intolerance are mixed. To quote a meta-study’s conclusion, “We found that LGG may have moderate-quality evidence to promote oral tolerance in children with CMA and may facilitate recovery from intestinal symptoms. However, this finding must be treated with caution, and more powerful RCTs are needed to evaluate the most effective dose and treatment time for children with CMA.”

So, more studies are necessary to prove a direct connection. Like with any probiotic, people’s reactions can differ a lot, and it’s important to think about all the available evidence before deciding if L. rhamnosus works well for treating lactose intolerance. You should always talk to a doctor before trying any probiotic supplement for a particular health issue. And I’d rather recommend a lactase enzyme for people suffering from lactose intolerance. 

Can you take Lactobacillus rhamnosus daily?

Most healthy individuals can generally take Lactobacillus rhamnosus daily as a probiotic supplement (or through consuming fermented foods containing live cultures, which is a GREAT way to get probiotics). Taking L. rhamnosus daily may help maintain a healthy balance of gut bacteria, support digestion, and potentially provide other health benefits. One quality manufacturer of this bacteria is Culturelle, who I review in my comparison of Florastor vs Culturelle.

However, certain individuals should be cautious when taking a supplement. And while I always recommend talking to your doctor, these people should really 100% consult their primary care physician before beginning any probiotic supplementation, including L. rhamnosus. These groups include:

  1. People with weakened immune systems, such as those undergoing cancer treatment, HIV/AIDS patients, or those who have had organ transplants.
  2. Individuals with underlying health conditions or taking medications that may interact with probiotics.
  3. Infants and young children, as their immune systems are still developing and may be more susceptible to infections.
  4. Pregnant or breastfeeding women, as there is limited information about the safety of certain probiotics during pregnancy and lactation.

What foods might contain Lactobacillus rhamnosus?

Some foods contain L. rhamnosus, although it’s often hard to figure out which specific bacteria any particular product has. But, here are some of the foods that might have this species of probiotic:

  1. Yogurt. Look for ones with “live and active cultures” to ensure the presence of probiotics. Some brands may list specific bacterial strains, while others may not. Read my article on how much probiotics are in yogurt.
  2. Cheese: Certain types of cheese, such as aged cheddar, gouda, and mozzarella, may contain L. rhamnosus and other beneficial bacteria. The presence of probiotics in cheese can vary depending on the production process and specific bacterial strains used. I don’t really know how you can know which probiotics are in any particular cheese.
  3. Probiotic-fortified products: Some food manufacturers add L. rhamnosus and other probiotics to their products to increase their health benefits. I’ll do my best to find some examples, but I think there are a few snack bars that may have probiotics in them.
  4. Sauerkraut: While traditionally made sauerkraut primarily contains Lactobacillus plantarum, some varieties may also contain L. rhamnosus. Sauerkraut is fermented cabbage and can be a source of various beneficial bacteria.
  5. Kimchi: spicy Korean fermented cabbage, which is surprisingly tasty.

It’s important to note that the presence of L. rhamnosus and other probiotics in these foods can vary depending on the fermentation process, storage conditions, and product freshness. Eating probiotic-rich foods is a great way to try to help with gut health.

Overall, is L. rhamnosus a good probiotic?

Lactobacillus rhamnosus is a widely used probiotic bacteria with potential health benefits. You are likely to see it listed in many (or most) of the multi-strain probiotics on the market, and healthy people shouldn’t be afraid of using it as a probiotic. It may help improve gut health, reduce anxiety and stress, alleviate allergies, and support weight management. However, the evidence for its effects on eczema and lactose intolerance is relatively weak and requires further research. One supplement that you can get it – in a blend with several other strains – is Good Girl Probiotics, which is designed for women’s health.

Most healthy individuals can take L. rhamnosus daily through probiotic supplements or by consuming fermented foods such as yogurt, kefir, certain cheeses, sauerkraut, kimchi, and tempeh. However, those with weakened immune systems, underlying health conditions, infants, young children, and pregnant or breastfeeding women should consult their doctor  before starting any probiotic supplementation. And anyone experiencing any serious health issues – see your doctor, don’t just try a probiotic!

Pharmacist Kari Raman

I’m Kari Raman PharmD, RPh, and I am a licensed, practicing pharmacist. I hold a Doctorate in Pharmacy from The University of the Pacific, and I’ve served patients in retail, compounding and hospital pharmacies.

Probiotics are confusing!

One of the most common questions I get asked by patients is about probiotics. And the truth is, probiotics are not as well understood by the healthcare community as they should be.

So I’ve been reading a lot of probiotic clinical trials, and sharing what I’m learning here.

I hope Pharmacist Probiotics helps you find out if there is a type of probiotic that works for you!