I used to walk around ruminating, struggling with inner turmoil and nervousness all the time.
It never went away.
It was impossible to shake.
It wore me down and ruined the quality of my life.
There’s no doubt that fear and vigilance are helpful when you’re faced with an actual threat.
But an unnecessarily high state of worry and arousal when there is nothing threatening you?
That’s a nightmare.
It doesn’t have to be that way though.
And probiotics are one way to do that.
Probiotics can improve your mental health by changing the mixture of bacteria in your gut (1-2).
It is estimated that 100 trillion bacteria, and 500 to 1,000 species of bacteria, live in the human gut. These gut bacteria, collectively known as the gut microbiome, help with digestion. But an increasing amount of research suggests that they also communicate with your brain through the microbiome-gut-brain axis, affecting your thoughts, feelings and behaviour (3-4).
A dysfunctional gut microbiome has been linked to a number of psychiatric conditions, including anxiety.
In fact, anxiety and gut health are very tightly linked.
Research shows that people who have digestive disorders are more likely to have anxiety, and those with anxiety have higher rates of gastrointestinal disease (5-7).
And studies show that when digestive disorders improve, anxiety improves as well (8).
But don’t worry!
You can improve your gut health and anxiety at the same time with the use of probiotics.
Studies show that certain probiotic strains can improve anxiety by:
- Stimulating the vagus nerve;
- Producing neurotransmitters, such as GABA and serotonin;
- Reducing stress hormone levels;
- Reducing inflammation, one of the major underlying causes of anxiety and mental illness;
- Increasing BDNF levels;
- Crowding out pathogenic bacteria;
- Increasing nutrient production and absorption (9-10).
- Lactobacillus rhamnosus
Lactobacillus rhamnosus is a bacterium found in the human gut. It is one of the most popular probiotic species found in supplements.
Preliminary research suggests that supplementing with lactobacillus rhamnosus (strain GG) can lower anxiety in humans (11).
GABA is the main inhibitory and relaxing neurotransmitter in the central nervous system, and studies suggest that lactobacillus rhamnosus (strain JB-1) may reduce anxiety by changing the expression of GABA receptors (12-14).
In one study, researchers gave lactobacillus rhamnosus (strain JB-1) to mice, and it reduced their anxiety-like behaviours.
But when researchers removed part of their vagus nerve, lactobacillus rhamnosus did not reduce their anxiety, suggesting that probiotics actually communicate with the brain and improve mental health through the vagus nerve (15-16).
Lactobacillus rhamnosus (strain GG) has also been shown to reduce obsessive-compulsive disorder (OCD)-like behaviour in mice. In fact, researchers found it worked just as well as fluoxetine, an SSRI antidepressant commonly used to treat OCD (20).
So if you struggle with OCD or obsessive-compulsive tendencies, it’s definitely worth trying a probiotic that includes lactobacillus rhamnosus!
Lactobacillus rhamnosus can also be found in some yogurt and dairy products, such as fermented and unpasteurized milk and semi-hard cheese.
But I typically don’t recommend eating these foods because a lot of people cannot tolerate dairy products, and they can actually worsen their anxiety and other mental health problems.
So supplementing with Lactobacillus rhamnosus is likely a better choice.
- Bifidobacterium longum
Bifidobacterium longum is another probiotic present in the human gut, and it’s often added to food because it can help prevent the growth of pathogenic organisms.
This probiotic strain has been proven to help treat depression, but it also can reduce anxiety!
Researchers have found that bifidobacterium longum (strain R0175) can reduce cortisol and alleviate psychological distress in humans (including obsessions, compulsions, paranoia, and anxiety) (21-23).
And lots of animal research shows that bifidobacterium longum (strain 1714) can significantly reduce anxiety-like behaviour (24-27).
One study even found that a chronic infection in mice increased inflammation and caused anxiety-like behaviour, but bifidobacterium longum (strain NCC3001) reduced inflammation, lessened anxiety and normalized behaviour (28-29).
Again, researchers have figured out that it works by acting through the vagus nerve (30).
- Lactobacillus reuteri
Lactobacillus reuteri is a probiotic with anti-inflammatory effects that scientists first discovered in the 1980s.
It is usually found in the human gut.
However, not all humans have it, and some people simply have very low levels of it.
Therefore, you may need to supplement with it to introduce and maintain high levels of it.
Research shows that Lactobacillus reuteri (strain 23272) can reduce anxiety-like behaviours in animals by reducing stress hormone levels and altering the expression of GABA receptors (43-44).
And one study found that the absence of lactobacillus reuteri causes social deficits in animals.
But by adding it back in to the guts of the animals, the researchers were able to reverse some of their behavioural deficits, which were similar to symptoms of social anxiety and autism in humans (45-46).
Therefore, lactobacillus reuteri is definitely the probiotic strain worth trying if you struggle with social anxiety or symptoms of autism.
- Lactobacillus fermentum
Lactobacillus fermentum is another probiotic species that is part of the human microbiome and commonly found in fermented vegetables, including sauerkraut, pickles, brined olives, kimchi.
It hasn’t been studied as much as other lactobacillus probiotic species.
But there still is some evidence that is may be able to help treat anxiety, especially if you have a long history of antibiotic treatment.
Research shows that antibiotics can trigger anxiety in animals by disturbing the microbiome.
But by giving animals lactobacillus fermentum (strain NS9), researchers can reduce the inflammation and reverse the psychological problems brought on by antibiotics, including anxiety-like behaviour (47).
So if you’ve taken a lot of antibiotics over the years, or noticed that your anxiety got worse after taking a course of antibiotics, taking a probiotic supplement with lactobacillus fermentum (strain NS9) may be worth a try.
- Bifidobacterium breve
Last but not least, bifidobacterium breve is a beneficial bacterium found in human breast milk and the human gut. But the amount in your gut declines as you get older (48).
Research shows that bifidobacterium breve (strain 1205) can reduce anxiety-like behaviour in animals (49).
Anxious animals also perform better on cognitive tests after being given it (50).
This makes bifidobacterium breve (strain 1205) a good probiotic option if you’re getting older or if your anxiety impairs your cognition and interferes with your ability to complete tasks.
It can be found naturally in some fermented foods.
The microbiome and probiotics are at the cutting-edge of neuroscience and mental health research and treatment. It hasn’t been that long since researchers first discovered that there is a gut-brain connection.
When I first found out about it several years ago, I started consuming probiotics, and they have definitely helped me recover from chronic anxiety.
But it’s important to point out that probiotics alone were never enough.
Yet for some people, probiotics can be life-changing, especially if you have digestive issues alongside your anxiety and worry.
Overall, I think they are absolutely worth a try!
If you buy a probiotic supplement, take it for at least a month and see how you feel. Stop taking it if you start to feel worse. You may need to be your own guinea pig and test out different probiotic supplements to find the one that reduces your anxiety the most.
I typically recommend people try one probiotic strain at a time to figure out how they respond to each one. This is because some people like myself often have a bad reaction to one strain, but a good reaction to another.
If all else fails, consider simply adding fermented foods into your diet and see how that goes instead.
Fermented foods likely contain many strains of bacteria that have not been documented in the scientific literature.
That said, there is a downside with fermented foods. The bacteria in fermented foods will vary depending on the batch, and there is sometimes the risk of them containing pathogenic bacteria.
Overall, I hope this article helps you, and please share it with anyone you think might benefit from it.