L. Reuteri For Anxiety: A Probiotic That Boosts Oxytocin & Treats Autism?

Could replenishing your gut flora with L. reuteri help combat anxiety?

According to research… yes, it can!

Today we’re going to look at how the lactic acid bacteria Limosilactobacillus reuteri can improve your overall health and well-being, reduce anxiety levels and maybe even reverse autism-like symptoms!


1. L. reuteri is a well-studied, safe probiotic bacteria that is really good for gut health; it reduces intestinal permeability and calms down anxiety (among many other benefits).

2. L. reuteri boosts oxytocin levels and thus is a promising treatment for autism spectrum disorder and similar issues.

What Is Limosilactobacillus Reuteri?

In your gut lives bacteria, yeast, viruses and other creatures, collectively known as the gut microbiome.

Limosilactobacillus reuteri, or L. reuteri, is one such creature!

*For some reason this bacteria recently changed name from Lactobacillus reuteri to Limosilactobacillus reuteri.

L. reuteri is a species of lactic acid bacteria that reside in the intestines and stomach of most humans. It is also found in human breast milk which means our gut gets colonized at an early age with this beneficial bacteria.

Interestingly, in the 1960s L. reuteri was found in 30-40 percent of the population, whereas nowadays it’s only found in 10-20 percent of people.

“So… what’s so interesting about this bacteria?

Well, there’s been tons of research done on the health-promoting effects of L. reuteri, and I’ve also seen many anecdotes of it being therapeutic for a wide range of health issues.

I’ve personally seen great benefits from taking L. reuteri and I believe it can be super useful for fixing a dysfunctional gut microbiome – and replenishing your gut with this probiotic bacteria can help reduce anxiety, improve mood and even reverse ASD-like symptoms.

How Can L. Reuteri Improve Your Health?

Research suggests that L. reuteri is a very beneficial bacteria to have in your gut.


L. reuteri can help rebalance your gut microbiome and kill of pathogens.

It produces its own antibiotic substance called reuterin. Basically it uses reuterin as “chemical warfare” to fight off other competing bacteria.

This is one of the reasons why L. reuteri can be so effective for shifting the gut microbiome in a positive direction (increasing beneficial Lactobacillus species) and inhibiting the growth of more pathogenic bacteria e.g E. coli, yeasts, fungi and protozoa.


L. reuteri has systemic anti-inflammatory effects.

L. reuteri helps your immune system out by reducing the production of “bad” pro-inflammatory cytokines, and promotes the development of “good” T regulatory cells which help reduce inflammation and prevent autoimmunity.


It’s awesome for gut health.

Gut-derived bacterial toxins such as lipopolysaccharides (LPS) are a constant threat to our health.

This study showed that giving mice L. reuteri for 1 week improved intestinal integrity and was highly protective against LPS-induced “leaky gut” and inflammation/oxidative stress.

In other words:

Colonizing your gut with L. reuteri helps improve intestinal barrier function and thus can decrease microbial toxins from translocating across the gut wall into systemic circulation = decreasing systemic inflammation…

…and as we’ll see later this can help reduce anxiousness!

Studies on The Health Benefits of L. Reuteri

As I mentioned before there’s been a progressive decline of L. reuteri in the human microbiome over the last few decades (probably due to our modern lifestyles, the increased use of antibiotics, lifestyle factors such as stress and junk food diets).


If you’ve lost the natural population of L. reuteri bacteria in your intestines, directly supplementing it can be a viable way of re-colonizing your gut flora as it’s been shown to survive the acidic environment of the stomach.

My experience with using L. reuteri is that I definitely felt more sociable; it made it is easier/more natural to connect with other people. Usually I’m more introverted and don’t really seek out social interactions.

This could probably be explained by the boost in oxytocin levels which I’m going to elaborate more on soon.

I’ve also seen reports of people getting back tons of energy, new hair growth, improved gut health, better and faster digestion, more regular bowel movements, getting sick less often, and so on.

These kind of positive changes are not so surprising when you look at some of the studies done on L. reuteri:

All in all, it’s pretty awesome stuff!

Now let’s take a closer look at how L. reuteri can help your brain out, improve mood/sociability and reduce anxiety!

L. Reuteri & The ‘Gut–Microbiota–Brain Axis’

The gut is your “second brain”…

…your thoughts, emotions, and how you’re feeling is largely influenced by your gut.

Researchers like to call this the ‘gut–microbiota–brain axis’ = the 24/7 bidirectional communication between your brain and gut.

We know from recent studies that there are distinct changes in the gut microbiome of depressed/anxious individuals.

And listen to this:

When you take the microbiome from a group of chronically stressed mice and transfer it to healthy mice (i.e you do a fecal microbiota transplantation), these healthy mice also become anxious and depressed!

Crazy stuff.

So, it’s obvious that your gut and gut microbiome can have a massive impact on mental health.

If you have a messed up gut microbiome from previous antibiotic courses, poor diet, etc, then L. reuteri could help shift things in the right direction…

…and as we discussed earlier a healthier gut flora means less nasty bacterial toxins translocating into systemic circulation, reduced blood–brain barrier disruption and less neuroinflammation.

How L. reuteri Can Reduce Autism-Like Symptoms

*Big fat disclaimer: I am NOT claiming that L. reuteri is a cure for autism – I’m only reporting on the findings of studies done on rodents, which may or may not be applicable to humans. With that said, there is actually an ongoing study in Italy using L. reuteri in children with autism spectrum disorder.

Here’s a very interesting study done on mice and the connection between the gut microbiome, reduced oxytoxin and social deficits/autism-like symptoms.

Taken from: https://www.cell.com/cell/fulltext/S0092-8674%2816%2930730-9

To briefly summarize:

In the offspring of mothers eating a “junk food high-fat diet”, L. reuteri was found to be 9x lower. This caused behavioural changes and social/synaptic deficits in the offspring, as well as reduced oxytocin production.

However when these mice were given a probiotic containing L. reuteri = it made them social again and improved brain plasticity!

The mechanism behind this seems to be that L. reuteri can increases oxytocin levels in the brain.

Oxytocin- big ass molecule

Oxytocin – ‘the love hormone’ – is a peptide hormone that enables you to feel a connection and bond with other humans. During social interaction oxytocin is released in the brain which triggers ‘social reward’.

Thus it kind of makes sense that individuals with autism have been found to have lower levels of oxytocin.

L. Reuteri Increases Oxytocin Via The Vagus Nerve

The same group of researchers later did a similar study where they again showed that treatment with L. reuteri restored social deficits in different autism spectrum disorder models.

Taken from: https://pubmed.ncbi.nlm.nih.gov/30522820/

What they discovered was that L. reuteri promotes social behavior not through restoring the gut microbiome…

…but instead via activation of the vagus nerve, the main nerve that connects the gut and the brain. This activation of the vagus nerve stimulated the neurons in the brain that produce oxytocin.

This adds yet another layer of depth to the complexity of how your gut affects your brain!


In these studies done on mice, L. reuteri was able to change the gut microbiome and stimulated vagal signalling, boost oxytocin levels and reverse ASD-like symptoms!

How L. Reuteri Can Help You Fight Anxiety & Depression

I believe we’ve already hammered home the fact that the gut microbiome influences behaviour and mental health.

But just to recapitulate once more:

In this study the researchers injected mice with bacterial endotoxins/LPS at 6 weeks of age (mice puberty) or at 10 weeks of age (adult mice).

Following this treatment the pubertal mice showed significant changes in gut flora composition including depletion of Lactobacillus strains, and in the male mice this caused long-lasting anxious behaviour.

The next experiment was that they also gave the mice L. reuteri throughout puberty…

…what they found was that colonizing the gut with L. reuteri protected against the LPS-induced anxious behaviour and also reduced stress reactivity in adulthood.

(This effect was only seen in the male mice which I’m not 100% sure about why… but according to the authors L. reuteri treatment also reduced anxious behaviour in female mice that didn’t get any injection of inflammatory LPS.)

In another study done on mice, L. reuteri together with B. adolescentis alleviated anxiety and depression by suppressing stress-induced gut dysbiosis and lowering gut inflammation. As a result, the mice had less LPS and pro-inflammatory cytokines floating around in the blood.

And lastly, giving L. reuteri to depressed mice (which was caused by chronic stress) improved the gut microbiota and reduce depressive-like behaviours, compared to the control group!

To Sum Up The Mental Health Benefits of L. Reuteri

  • Endotoxin/LPS leaking out of the gut into systemic circulation is a huge problem, it can cause ‘sickness behaviour’ and chronic anxiety and depression.
  • Supplementing with L. reuteri improves your gut microbiome/gut health and can help prevent “leaky gut” and LPS-induced anxiety… Fun fact is that coffee actually has a similar protective effect on preventing LPS-induced anxiety, which I wrote about in this article.

How To Take Limosilactobacillus Reuteri? And Is it Safe?

It’s not rocket science…

Get some L. reuteri and start eating it!

There have been lots of clinical studies done on L. reuteri and it’s deemed safe for newborn babies, children, adults and pregnant women. No adverse effects have been observed even when taking 10 billion CFU per day.

The first couple of days there may be some uncomfortable symptoms as your gut microbiome adjusts to a new bacterial strain, and likely also from the reuterin killing off other pathogenic bacteria, yeast, fungi, etc.


….what’s the best brand/pill/tablets?

Here’s a pretty good L. reuteri supplement (on Amazon).

The most affordable way to supplement L. reuteri is to buy these pills and then use them make your own yogurt. Besides it being the cheapest option it’s also plausible that you’ll get a better effect by allowing the bacteria to first activate and multiply through fermentation.

A very basic recipe would some kind of milk (plant based milks should work as well) + a couple tablets of L. reuteri in a yogurt maker for 24-48 hours.

If you’re interested here’s a much more detailed recipe on how to make your own L. reuteri yogurt.

Of course you can also just buy higher dosed tablets (10 billion CFU), for instance BioGaia Osfortis, but it’s going to be more expensive versus the yogurt.

*Warning Before Taking Any Probiotic

There’s always a risk involved with taking probiotics IF you’re dealing with symptoms of SIBO (small intestinal bacterial overgrowth).

Basically SIBO means you have too much bacteria in the small intestines, and adding in MORE bacteria via probiotics could aggravate it. Typical symptoms of SIBO are things such as bloating, gas, feeling overly full, nausea shortly after eating.

However, in some cases L. reuteri can actually reduce pathogenic overgrowth of organisms such as M. smithii – a.k.a methane dominant SIBO.

So it will depend on your individual context and what’s going on with your body!


I believe that’s pretty much all for today.

Let me know if you’ve had a chance to try L. reuteri and how you felt!

For the best anti-anxiety effects you’d want to combine L. reuteri with a good diet, sleep, sunshine, mindfulness exercises, maybe some targeted nutritional supplements for addressing deficiencies such as thiamine/vitamin B1, and so on.

Here’s an article on all of those things (and more) if you are interested.


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