Do probiotics help anxiety?
Psychobiotics are probiotics aimed at mood. For anxiety, they may help a little, but not reliably. Four big reviews disagree. And the NHS warns that trial probiotics can differ hugely from shop ones.
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Do probiotics help anxiety?
Psychobiotics are probiotics tested for mood and anxiety. Do they help? Maybe a little.
Across 14 trials in 1,527 people, probiotics did not clearly ease anxiety. A review of 34 trials found a small effect.
A 2025 Oxford review looked only at people with a diagnosed mental health condition. In 9 trials, probiotics gave a moderate drop in anxiety. But results varied a lot from trial to trial.
| Review | Who was in the trials | What it found for anxiety |
|---|---|---|
| Reis 2018, 14 trials | Healthy people and patients | No clear drop. |
| Liu 2019, 34 trials | Mixed groups | A small drop. |
| Zhang 2025, 49 trials | People with anxiety or low mood symptoms | A drop, but trial quality was limited. |
| Asad 2025, 9 trials | People with a diagnosed mental health condition | A moderate drop. Results varied a lot. |
Sources: Reis 2018; Liu 2019; Zhang 2025; Asad 2025
Why the mix? The trials used different strains, lengths and people. The newest review says more large, high-quality trials are needed.
So treat a probiotic as an extra, not your plan. If worry is hard to control and affects your daily life, see a GP first.
What are psychobiotics?
A psychobiotic is a live organism, such as a bacterium, that helps people with a mental illness when taken in large enough amounts. Put simply, it’s a probiotic aimed at mood.
The idea comes from the way your gut and brain send signals both ways. Our gut-brain axis guide explains how.
Most of the early promise came from rats and mice. The scientists who named psychobiotics said that in rodents, some seemed to ease anxiety or low mood.
Animal results don’t always carry over to people. A 2018 review found that for anxiety they hadn’t yet.
Psychobiotics have also been tested for low mood. In 7 trials of people with depression, probiotics helped only alongside antidepressants, not on their own. Some of those reviewers had funding from a probiotic maker.
On an antidepressant? Never stop or change a prescribed medicine without your prescriber.
Which probiotics have been tested for anxiety?
There’s no proven best strain. A strain is one exact type of bacterium, named by a code on good labels.
| What was tested | Who took it | What happened |
|---|---|---|
| L. helveticus R0052 with B. longum R0175 | Healthy adults, for 30 days | Less overall distress. The anxiety score just missed the usual cut-off for a clear result. |
| L. rhamnosus | Rats and mice | The only type that eased anxious behaviour. Too few studies to be sure. |
| Prebiotics (fibre that feeds gut bacteria) | 34 trials, mixed groups | No better than a dummy pill. |
Sources: Messaoudi 2011; Reis 2018; Liu 2019
The NHS says a probiotic that helps one problem may not help others. So a strain sold for bloating tells you little about anxiety.
If you try one, pick a label with the full strain code. Then you can check it against the trials. For gut problems, see do probiotics work?
Will a shop probiotic work like the trial ones?
Not always. The NHS says there’s likely to be a huge difference between trial probiotics and the yoghurts and supplements in shops.
Probiotics are classed as food, not medicine. So the NHS says we can’t always be sure what’s inside. A product may lack the bacteria on the label, hold too few to work, or not survive to reach your gut.
The good news: for most people, probiotics appear to be safe. With a healthy immune system, they shouldn’t cause unpleasant side effects.
If you want to try a probiotic for anxiety
- Keep seeing your GP or therapist, and keep any treatment they give you.
- Never stop or change a prescribed medicine, such as an SSRI, without your prescriber.
- Have a health condition or a weak immune system? Talk to a doctor before any probiotic supplement.
- Pick a label that names the full strain code, so you can check it against the trials.
- Set a stop date, such as 8 weeks. In people with a diagnosed condition, the Oxford review found benefit from up to 8 weeks of use.
- Score your worry from 0 to 10 each week, so you can see if anything changes.
Sources: NHS: probiotics; NHS: anxiety; Asad 2025
No change by your stop date? Stop buying it. For food sources, see fermented foods.
What does the NHS suggest for anxiety?
Over 18? You can refer yourself to NHS talking therapies without seeing a GP.
What a GP may offer for generalised anxiety
- 1
Talking therapy
Usually CBT, where a therapist helps you change how you think and act. Often tried first.
- 2
Medicine
Usually an SSRI, a type of antidepressant.
- 3
Specialist team
A community mental health team, if needed.
Sources: NHS: generalised anxiety disorder; NHS: CBT
The NHS also lists things to try yourself. Exercise, such as running, walking, swimming or yoga, can reduce anxiety and stress.
Try calming breathing, enough sleep and regular meals. Cut back on coffee, tea, cola and energy drinks. Don’t use alcohol, cigarettes, gambling or drugs to cope.
For other options, see natural remedies for anxiety and supplements for stress and anxiety.
When to speak to a GP
Most people feel anxious sometimes. Book an appointment if:
- You think you might have generalised anxiety: worry that is hard to control and affects your daily life.
- You’ve been diagnosed with anxiety and treatments are not helping.
- You have a health condition or a weak immune system and want to try a probiotic.
- You need urgent help for your mental health. Call 111 and choose the mental health option, or ask for an urgent GP appointment.
- Someone’s life is at risk, or you don’t feel you can keep yourself or someone else safe. Call 999 or go to A&E.
Need to talk now? Call Samaritans free on 116 123.