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NCT Number: NCT06463769

Impact of Diet on the Microbiome-Immune-Brain Axis in Parkinson's Disease

Habitual adherence to a predominantly plant-based diet, rich in low-processed food (LPF) has been associated with a reduced risk for development and slower progression of Parkinson's Disease (PD). This could be due to neuroprotective effects by modulation of the gut microbiota and decreased neuronal and metabolic inflammation. So far, the effect of a predominantly plant-based LPF-diet on the microbiome-immune-brain axis in patients with PD remains unknown. In addition, the influence of dietetic measures on the gut microbiome is variable and may depend on (long-term) adherence as well as on PD-specific factors and lifestyle.

The investigators hypothesize that compared to an average German diet, the predominantly plant-based New Nordic LPF-diet, as a culturally adapted diet, which is rich in fermentable fiber and phytochemicals, will have beneficial effects on the gut microbiome of patients with PD by increasing the abundance of short-chain fatty acid (SCFA)-producing bacteria (primary outcome) and will improve gut motility, metabolic resilience, and inflammation (secondary outcomes). Furthermore, the investigators postulate that a patient-centered dietary intervention program, including a multifaceted patient education and supported by a web-application, will lead to high adherence as a key determinant of long-term changes in the gut microbiome. This dietary intervention will be accepted by patients as a low-threshold treatment that balances personal benefits, therapeutic barriers and ethical concerns of early risk disclosure in PD.

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Key information

Conditions

Parkinson Disease Basal Ganglia Diseases Brain Diseases Central Nervous System Diseases Movement Disorders Nervous System Diseases Neurodegenerative Diseases Parkinsonian Disorders Synucleinopathies

Age range

50 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Institute of Human Nutrition, Kiel, Germany

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About this study

In a pilot-intervention study, our project will:

  • develop a practical, low-threshold diet intervention for patients with prodromal and clinical PD. Adherence will be promoted (i) by a patient-oriented approach, (ii) by implementation of the predominantly plant-based New Nordic LPF-diet that is scientifically-based, culturally adapted, sustainable and culinary and (iii) by an innovative web-application.
  • investigate the acute effects of the predominantly plant-based New Nordic LPF -diet on the microbiome (abundance of SCFA-producing bacteria), gastrointestinal motility, inflammation as well as metabolic and Parkinson-specific clinical outcomes in individuals with prodromal and clinical PD.
  • investigate potential determinants of long-term changes in the gut microbiome (e.g. dietary adherence, gastrointestinal motility, meal timing and frequency), and factors associated with a high adherence (e.g. acceptance of diet as therapeutic intervention in the prodromal phase, health-related quality of life).

The patient-centered intervention program will be tailored to individual needs and preferences of individuals with prodromal and clinical PD. It will be designed to impart knowledge (e.g. on sustainability and health effects) and food literacy (e.g. food merchandize and culinary skills) in group meetings and culinary medicine workshops. Recipe suggestions and shopping guides will consider individual abilities and needs and a web-application is used for information, increasing self-efficacy, motivation, and monitoring. To ensure an easy integration of the diet into everyday life, partners will be included in the program, if applicable. Moreover, cultural preferences as well as financial resources will be considered. Regular feedback using statistics on nutrient intake and overall progress will be implemented to encourage adherence.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • patients with probable prodromal PD (according to predefined criteria)
  • patients with clinical PD with slight to moderate disease severity (Hoehn & Yahr 1-2.5)
  • habitual Western Diet (≥30% of energy intake from ultra-processed food)

Exclusion criteria

  • current adherence to a plant-based diet
  • food allergies or intolerances
  • significant diseases of the gastrointestinal system (e.g. celiac disease) or central nervous system, diabetes mellitus
  • underweight (BMI <18.5 kg/m2)
  • active smoking
  • expected changes in medication or antibiotic treatment during the intervention

Treatment and study plan

8 week predominantly plant-based New Nordic LPF-diet program

Behavioral

An 8-week patient-centered dietary intervention program will be implemented to maintain a predominantly plant-based New Nordic LPF-Diet.

maintenance of the predominantly plant-based New Nordic LPF-diet

Behavioral

Follow-up of long-term adherence to the diet at one and six months after completion of the intervention program.

Primary outcomes

  1. abundance of key SCFA-producing gut bacteria

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    analysis of stool samples

Secondary outcomes

  1. systemic inflammation markers

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    hsCRP and IL-6 in serum

  2. metabolic resilience

    Time frame: pre vs. post intervention (8 weeks)

    modeling of one parameter (metabolic resilience) including information on postprandial glucose, insulin, triglycerides and NEFA following a mixed meal tolerance test

  3. gastrointestinal peptide-hormones

    Time frame: pre vs. post intervention (8 weeks)

    ghrelin, GLP-1, PYY

  4. energy balance

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    changes in body weight

  5. energy partitioning

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    changes in body composition

Other outcomes

  1. clinical motor symptoms

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    clinical examination

  2. clinical non-motor symptoms

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    clinical examination

  3. gastric emptying

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    13C-breath test

  4. gastrointestinal transit time

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    using a test meal with food colouring and the time to colour appearance in stool

  5. gut motility

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    functional visceral MRI

  6. dietary adherence via serum markers

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    serum carotinoid and Trimethylamine oxid-levels will be combined and tertiles will be formed

  7. dietary adherence via healthy Nordic food Index

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    healthy Nordic food Index using data from a food frequency questionnaire

  8. food literacy effectiveness

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    self-perceived food literacy scale (questionnaire)

  9. patient acceptance

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    Parkinson's Disease Questionnaire (PDQ-39)

  10. patient quality of life

    Time frame: pre vs. post intervention (8 weeks) + pre intervention vs. follow-up 6 months after completion of intervention

    Ways of Coping Questionnaire (WCQ)

Study contacts

Contact information is provided by the study sponsor or research team.

Anja Bosy-Westphal, PhD, MD

CONTACT

[email protected]

+494318805674

Eva Schäffer, MD

CONTACT

[email protected]

+49431 500 23800

Sponsors and collaborators

Lead sponsor

University of Kiel

Other

Collaborators

  • University Hospital Schleswig-Holstein

Registry information

Official study title

"Impact of Diet on the Microbiome-Immune-Brain Axis in Parkinson's Disease" as Part of the Collaborative Research Center 1697 "Targeting the Microbiome-Immune-Brain Interaction in Neurodegeneration"

Important dates

Study start
2026
Primary completion
2027
Study completion
2028
First posted
Jun 18, 2024
Registry last updated
Apr 29, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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