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Vaccines and Immunotherapies (VIT)


Probiotic supplements for gut immune health (PROOV IT II)

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About the study

The purpose of this pilot study is to determine if taking a probiotic in combination with antiretroviral therapy (ART) can help reduce inflammation and harmful immune activation in those who don’t respond completely to ART.

Probiotic products are live bacteria that may provide health benefits and are often referred to as “beneficial” bacteria. The specific probiotic used in this study, Visbiome, has been approved by Health Canada as a Natural Health Product. However, its use in this research study is experimental.

About the disease/condition

Approximately 25% of HIV-infected individuals who start taking ART have a sub-optimal response meaning that their immune system (CD4 count) doesn’t improve as expected, even though the virus is suppressed by their medications. These individuals are sometimes known as immune non-responders (INRs). These individuals are at increased risk of AIDS-related deaths and non-AIDS related health problems that may be associated with increased immune activation and leaking of bacteria from the gut into the bloodstream.

Consistent use of ART to manage HIV is known to extend life expectancy by many years. However, many people living with HIV have more inflammation and immune activationrelated health conditions (like heart and brain diseases) compared to uninfected people, even after taking ART for a long period of time. This is a result of bacteria entering the bloodstream through a person’s gut lining that has been damaged by HIV. Although ART has drastically improved HIV care, it can take years of continuous ART to repair HIV-related damage to the immune cells in the gut.

This study will investigate whether fixing the damage to gut tissue by taking probiotics will improve the response to ART in INRs. There is considerable evidence that a change in the balance of beneficial and harmful bacteria influences gut immune health. For example, beneficial bacteria have been shown to enhance the ability of immune cells to fight harmful bacteria. Probiotics may improve the function and number of healthy immune cells in the gut to prevent the leakage into the bloodstream and ultimately reduce HIV-related health complications in INRs.

Study Approach

The duration of the study is 48 weeks. The study is double-blinded meaning that neither the participants or their doctor will know which treatment group they are in.

  1. Probiotic treatment group: Probiotic Visbiome (two sachets daily) + standard ART
  2. Control treatment group: Placebo (two sachets daily) + standard ART. A placebo has no active ingredient but looks the same as Visbiome.

Bloodwork and questionnaire material will be collected periodically throughout the course of the study. This information will be used to compare immune function, inflammation, and gut health between the two study groups.

Eligibility criteria

Inclusion Criteria:

  • Documented HIV-1 infection
  • Male and 18 years or older
  • Currently on ART (more than 2 years)
  • Undetectable HIV-1 viral load <50 copies/ml for the past 2 years
  • CD4 count must be <350 cells/ul at least 70% over the past 2 years
  • Ability to provide informed consent

Exclusion Criteria:

  • Current alcohol or substance use judged by the Investigator to potentially interfere with the participant’s study compliance
  • Taking pharmaceutical grade probiotics
  • Laboratory results in screening deemed abnormal for the purposes of this study
  • Significant underlying disease (non-HIV-1) that might impact disease progression or death

For full eligibility criteria please visit

Participating sites

Maple Leaf Medical Clinic
Toronto, Ontario, Canada, M5G 1K2
Contact: Colin Kovacs, MD

Toronto General Hospital, UHN
Toronto, Ontario, Canada, M5G 2N2
Contact: Sharon Walmsley, MD

Additional Information

If you would like more information on this clinical study, please refer to the participating site.

Principal Investigator:

Dr. Rupert Kaul, MD, PhD
University of Toronto
(416) 978-8607


Kim CJ, Walmsley SL, Raboud JM, Kovacs C, Coburn B, Rousseau R, Reinhard R, Rosenes R, Kaul R. Can Probiotics Reduce Inflammation and Enhance Gut Immune Health in People Living with HIV: Study Designs for the Probiotic Visbiome for Inflammation and Translocation (PROOV IT) Pilot Trials. HIV Clin Trials. 2016;17(4):147-157.

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