Exploring the impact of prebiotics and probiotics on mood and cognition 

Click here to participate


The University of Melbourne is conducting an 8-week clinical trial investigating the effects of dietary prebiotic foods and probiotic supplements on adult mental health and cognition

 Investigators: Prof Jerome Sarris, Ms Tanya Freijy, Prof Felice Jacka, Dr Jason Hawrelak, Prof Julia Rucklidge, Dr Rachelle Opie, Ms Georgina Oliver, Dr Jenifer Murphy, Ms Rosemary Arnold, Prof Chee Ng

What are probiotics and prebiotics?


 PROBIOTICS are live bacteria that provide health benefits when ingested in adequate amounts. They help to balance 'bad' bacteria in the gut environment, protect you from disease, and produce vitamins and other beneficial compounds. Probiotics are found naturally in fermented foods such as yoghurt and sauerkraut. In this study, a multi-strain probiotic supplement will be used to maintain control over type and amount of probiotics administered. Fermented foods high in probiotic bacteria will be excluded from the diet. A PREBIOTIC is a non-digestible type of dietary fibre that feeds the gut bacteria, thereby beneficially influencing the composition and/or activity of the gut microbial population. GUT FEELINGS will be the first randomised controlled trial examining the effects of food-based prebiotics on mental health.    

What does the study involve?


 If you are eligible to participate, you will be randomly allocated to take probiotic OR placebo capsules. You will be given capsules to take each morning and evening for the 8-week study period. In addition, you will be randomly allocated to follow a high-prebiotic diet OR make no changes to your diet.  ​ Over the 8-weeks, you will be required to attend 3 appointments at The Melbourne Clinic, Richmond, VIC. You will meet with one of the researchers and complete questionnaires and assessments regarding your mental health symptoms and physical health. At home, you will need to complete brief online assessments related to diet and mental health symptoms every fortnight during the study. Please note that participants are not paid for their involvement in the study. 

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Study Participation


 Do you live in Melbourne, Australia and want to participate in our 8-week research study?
We are looking to recruit adults aged 18-65 years who are generally healthy but experience low mood, anxiety, or stress, plus have scope for improvement in their diet
​Unfortunately, your are ineligible for participation if you: 

  • Currently take medication for a mental health condition, e.g. antidepressants 
  • Regularly take antibiotics or anti-inflammatory medication 
  • Have a BMI over 35
  • Are currently pregnant 
  • Have Irritable Bowel Syndrome, Inflammatory Bowel Disease, or chronic constipation 
  • Follow, or are required to follow a low-FODMAP diet.  

Please note that other exclusions may apply
Click the button below, or visit to complete our pre-screener survey to see if you are eligible for study participation 


Take me to the Online Pre-screener

Contact Us

Gut Feelings Trial

The Melbourne Clinic Professorial Unit, 2 Salisbury Street, Richmond, Victoria 3121, Australia

03 9487 4748

Our Research Teams