OPTIMISM study

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What is the OPTIMISM trial?

OPTIMISM is a four-week study that aims to compare the effects of two dietary patterns on depressive symptoms and other outcomes including anxiety, microbiome composition, gut permeability, and inflammation among adults with and without depression. All meals and snacks will be provided to participants for the duration of the trial.

How are we doing this trial?

We are recruiting 44 adults with depression, and 22 adults without depression, from the Geelong and Melbourne regions. Participants will be randomly allocated to one of two dietary patterns and must only consume the meals and snacks provided to them for four weeks. We will measure changes in depressive symptoms, and other symptoms such as anxiety and gut symptoms, over this period. We will also collect blood and stool samples, which will provide information about how the different dietary patterns may impact participants.

What does the trial involve?

As part of the trial, you will be asked to:

  • Follow a specific dietary pattern for four weeks.
  • Consume only the meals and snacks provided.
  • Attend two in-person study appointments.
  • Provide a blood and stool sample at these two visits.
  • Complete a range of questionnaires.
  • Check-in weekly with a member of the research team via zoom.

In return you will:

  • Be provided with all meals and snacks for four weeks.
  • Be reimbursed upon study completion for parking or public transportation costs.

Who is eligible to participate?

For those with depression, you may be eligible to participate if you meet the following criteria:

  • Aged 18-65 years.
  • Have received a diagnosis of depression.
  • Live in Melbourne or Geelong.
  • Do not have a diagnosed food allergy, severe food intolerance or dietary restriction.
  • Are not pregnant or breastfeeding.

For those without depression, you may be eligible to participate if you are:

  • Aged 18-65 years.
  • Live in Melbourne or Geelong.
  • Do not have a diagnosed food allergy, severe food intolerance or dietary restriction.
  • Are not pregnant or breastfeeding.

What do we hope to find?

This trial aims to improve understanding of how food can influence depressive symptoms.

Further information

  • 'Ethics Committee Project ID: 44424 (Monash); 96875 (Barwon Health)
  • Recruitment end date: December 2025
  • The study approval organisation: Monash University
  • Study has advertising approval

Interested in participating?

If you would like to know more about this study please contact optimismscreen@monash.edu or call 0404 434 345.

If you are interested in participating please complete this pre-screening questionnaire.