RecruitingInterventional

Gut feeling: probiotics with sertraline in primary care depression

This study is investigating if adding a probiotic drink to the antidepressant medication, sertraline, could help people with depression. Depression is very common, and researchers think that the balance of bacteria in our gut might affect our mood. This early-stage study will involve 106 people aged 18-60 with moderate depression over 14 weeks. Half will get the probiotic and sertraline, and the other half will get sertraline and a dummy probiotic. Researchers want to see if this combination is practical for patients and if there are any early signs of improvement in mood, quality of life, and gut health. Your GP will be informed, and you can withdraw at any time.

At a glance

Status

Recruiting

Sponsor

Symprove UK

Enrolment target

106

Start

12 Jan 2026

Estimated completion

12 Jul 2026

Depression

What is this study about?

This study, called "Gut Feeling," is exploring new ways to help people living with depression. Depression is a common mental health condition that affects many people in the UK. Even with current treatments, some people continue to struggle with their symptoms. Recent research has suggested a fascinating link between our gut health – specifically the types of bacteria living in our intestines – and our mood. Probiotics are beneficial bacteria that can help keep our gut healthy.

Researchers want to find out if taking a probiotic alongside a common antidepressant medication, sertraline, could be a helpful approach. This is a "pilot study," which means it's an early step to see if this idea is practical and acceptable for people with moderate depression. They'll also be looking for any early signs that this combination might improve a person's quality of life, their depression symptoms, and their overall gut health, compared to just taking sertraline with a dummy probiotic.

The main goal right now isn't to prove that this combination definitely works, but rather to see if it's a good idea to research further in a larger study. It's about exploring new possibilities to potentially offer better treatment options for depression in the future.

Key takeaways

Exploring if probiotics can help with depression alongside sertraline.
A 14-week study with 5 visits for check-ups and assessments.
Participants will receive either a probiotic or a dummy liquid.
Aims to improve understanding for future, larger studies.
Potential mild side effects from probiotics, like bloating.
Your GP will be informed about your involvement.

Who may be eligible?

This study is looking for volunteers between the ages of 18 and 60 who have been diagnosed with moderate depression. You would also need to have been taking your current dose of antidepressant medication steadily for at least the last three weeks.

There are several reasons why you might not be able to join the study. These include if you are pregnant, have certain ongoing health conditions like autoimmune diseases, inflammatory bowel disease, or severe heart or kidney problems. You also wouldn't be able to participate if you already take probiotic supplements, have certain other mental health conditions like psychosis or an eating disorder, or use specific medications like benzodiazepines or quetiapine regularly. Your doctor will be able to check all these details for you.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 60 years old?
Have you been diagnosed with moderate depression?
Have you been on a stable dose of antidepressant medication for at least 3 weeks?
Are you not currently pregnant or planning to be during the study?
Do you have no diagnosed autoimmune diseases or severe heart/kidney conditions?
Are you not currently taking probiotic supplements?

Answer every question to see your result.

What does participation involve?

If you decide to take part, the study will last for 14 weeks. You'll be randomly assigned by a computer to one of two groups. One group will take sertraline along with a liquid probiotic drink, and the other group will take sertraline with a liquid 'dummy' drink that looks just like the probiotic but has no active ingredients. Neither you nor the study team will know which drink you are receiving – this is to make the study as fair as possible.

During the 14 weeks, you'll have 5 visits to the study clinic. These visits will involve discussions about your progress, answering questionnaires about your mood and quality of life, and having blood samples taken. You will also have your blood pressure and BMI (Body Mass Index) checked. Your GP will be informed about your involvement, and you'll always have the right to leave the study at any time without it affecting your usual medical care. After the study finishes, you'll be able to find out the results.

Potential risks and benefits

Taking part means you'll have regular check-ups on your mental and physical health throughout the study, which could be a benefit. Some people might experience mild side effects from the probiotic, such as bloating or more frequent bowel movements, but these are usually minor. While there's no guarantee that participating will improve your mood or heart health, there is a possibility that you might feel better. The main purpose of this study is to help researchers learn more about depression and potential new treatments, which could lead to better future options for everyone. You can choose to stop participating in the study at any time.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

Denmark Street Surgery
City only
Darlington, United Kingdom

Common questions

What is a probiotic?

Probiotics are beneficial bacteria that live in your gut and can help keep your digestive system healthy. Some research suggests they might also influence mood.

What is sertraline?

Sertraline is a common medication used to treat depression. It's an antidepressant that helps balance certain chemicals in the brain.

Will I know if I'm getting the probiotic or the dummy drink?

No, neither you nor the study team will know if you're receiving the probiotic or the dummy drink. This is a common practice in research to make the results more reliable.

How long will the study last for each participant?

The study for each participant will last for 14 weeks, involving 5 visits to the study clinic.

Can I stop participating in the study at any time?

Yes, you have the right to withdraw from the study at any time without it affecting your medical care.

How to find out more

Paul Conroy

paul.conroy1@nhs.net +44 (0)1325 460731 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.