Public Defence: Christopher Storm Ligaard Christopher Storm T. Ligaard at Institute of Clinical Medicine will be defending the thesis “Clinical interventions of the human gut microbiota” for the degree of PhD (Philosophiae Doctor).

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Photo: Øystein Horgmo.

An electronic copy of the thesis may be ordered from the faculty up to 2 days prior to the public defence. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

Trial Lecture – time and place

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Adjudication committee

  • First opponent: Professor Max Nieuwdorp, Amsterdam University Medical Centers
  • Second opponent: Researcher Randi J Bertelsen, University of Bergen
  • Third member and chair of the evaluation committee: Professor II Mathias Toft, University of Oslo

Chair of the Defence

Professor Ketil Størdal, Faculty of Medicine, University of Oslo

Principal Supervisor

Professor II Johannes E. R. Hov, Institute of Clinical Medicine, University of Oslo


Growing evidence suggests that bacteria residing in the intestines have a significant impact on factors related to human health and disease. An increasing number of reports have demonstrated associations between gut microbiota and human diseases; however, most studies have yet to demonstrate causality. Knowledge on how we could induce alterations of gut microbiota through targeted interventions would increase our understanding of the complex interplay within this intricate ecosystem. This thesis includes three clinical trials aiming to induce perturbations in the gut microbial composition of individuals with an altered gut microbiota compared to healthy individuals. Longitudinal research efforts permit the exploration of the dynamics of gut microbiota and increase the functional understanding of its relationship with human health factors.

First, the gut microbiota of people infected with HIV was targeted using a probiotic milk supplement. Second, the effects on the gut microbiota of a common disease-modifying drug used for multiple sclerosis were evaluated with emphasis on the relationship with drug-associated gastrointestinal symptoms. Last, the effect of omega-3 fatty acids on the gut microbiota and blood lipids was tested in a population with familial hypercholesterolemia.

The treatments modulated the gut microbiota to a varying degree, and in this thesis, the author discusses factors related to the observed effects and the clinical relevance of these perturbations. A critical review of the methodology used is provided, with emphasis on the limitations that may have caused clinically relevant effects to be overlooked. Lastly, the author presents the experiences the research team has had after targeting the gut microbiota in three different clinical trials and concerns that should be considered when designing a clinical trial to target the gut microbiota.

Additional information

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Published Aug. 12, 2022 12:50 PM - Last modified Aug. 24, 2022 12:52 PM