Parkinson Disease (PD)NCT07682532
L-THEANINE AND MEDITERRANEAN DIET ON RBD, GI FUNCTION, AND INFLAMMATION IN PARKINSON'S DISEASE
A study testing Dietary Supplement in people with Parkinson Disease (PD), run by Medipol University at 1 site in Turkey (Türkiye).
Trial summary
Parkinson's disease is a progressive neurological disorder associated with severe dopaminergic neuron loss in the substantia nigra pars compacta. The decrease in dopamine cells in the gut in Parkinson's disease negatively affects bowel movements, and constipation is a common condition. Read more about this study
- Who is it for?
- Ages 50 to 80 years
- Conditions the study is for
- Parkinson Disease (PD)
- What is being tested?
- Dietary Supplement
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 52 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 2 May 2026to 20 Oct 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 50 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients diagnosed with Parkinson's Disease and classified as stage 1 according to the Hoehn-Yahr Staging (HYA), Patients without communication impairment (aphasia) Participants who sign the Informed Consent Form and volunteer to participate in the study Absence of dementia and Mini Mental State Examination (MMSE) score > 24 Living in the same household with a healthy spouse/partner Not taking prebiotic, fiber, probiotic, herbal, or high-dose vitamin or mineral supplements that may affect inflammation during the pre-onset period and throughout the study protocol
Who cannot join
- Patients with a history of severe heart, lung, liver, or kidney failure, primary psychiatric, developmental, or other neurological disease Patients using sedative/hypnotic medications Individuals consuming more than 200 mg of caffeine per day (approximately 2-3 cups of tea or 1 cup of coffee) Patients who smoke and consume alcohol Having undergone surgery related to bowel health Having a chronic infectious bowel disease Having a congenital bowel anomaly Using probiotics, antifungals, and/or antibiotics within the last three months Individuals with an autoimmune disease or weakened immune system Self-reported alcohol or drug use within the last 3 months Current use of over-the-counter medications, supplements, foods, and/or beverages that may affect stress, sleep, cognition, and/or mood Inability to swallow the study supplement due to swallowing anxiety Receiving treatment for a GI disease or condition diagnosed by a doctor other than constipation, gastroparesis, gastroesophageal reflux disease, or diverticular disease Positive results for human immunodeficiency virus (HIV) or Hepatitis B/C. Current history of active conditions of inflammatory bowel disease, irritable bowel syndrome, colitis, celiac disease, short bowel syndrome, colostomy, colectomy, gastrointestinal fistula, or strictures.
- Recent or current use of any antibiotic (within 4 weeks prior to the start of the study) Use of enemas or suppositories to relieve constipation Good adherence to the Mediterranean diet in the pre-start period according to the 14-item Mediterranean Diet Assessment Tool (score >6)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Turkey (Türkiye)1 site, 1 recruiting
- Recruiting
Medipol Mega Hospital
Istanbul
Rüken A Samancı, +90 543 939 15 94, rasamanci@medipol.edu.tr
Gözde Ülfer
About this study
Official title: THE EFFECT OF L-THEANINE SUPPLEMENTATION ON REM SLEEP BEHAVIOR DISORDER, GASTROINTESTINAL FUNCTION, AND INFLAMMATORY MARKERS IN PARKINSON'S DISEASE
Parkinson's disease is a progressive neurological disorder associated with severe dopaminergic neuron loss in the substantia nigra pars compacta. The decrease in dopamine cells in the gut in Parkinson's disease negatively affects bowel movements, and constipation is a common condition. Impairment of the intestinal barrier increases inflammation. Reactive oxygen species increase, and intestinal homeostasis changes. Alpha-synuclein levels increase in the gut. L-theanine is the most abundant amino acid in green tea leaves. Parkinson's patients exhibit increased oxidative stress along with decreased activity of glutathione peroxidase, superoxide dismutase, and catalase. L-theanine is believed to increase the activity of these enzymes and reduce oxidative stress. L-theanine administration has been found to increase total short-chain fatty acids in stool. Furthermore, it is suggested that L-theanine inhibits imbalances in oxidative stress and inflammatory responses by reducing inflammatory factors such as TNF-α, IL-6, and IL-1β. REM sleep disturbance is also a common problem in Parkinson's disease. Studies have shown that following L-theanine treatment, participants' Pittsburgh Sleep Quality Index (PSQI) scale scores improved. The gut microbiota regulates sleep and neurological states via the microbiota-gut-brain axis. L-theanine supplementation appears to be able to regulate gut bacterial composition to suppress neurotransmitters, cytokines, and other metabolites to regulate sleep. The protective effects of L-theanine administration on increased dopamine and other neurotransmitters, microbiota, sleep, and antioxidant enzymes may offer a glimmer of hope regarding its beneficial role in Parkinson's disease.
- Conditions
- Parkinson Disease (PD)
- Being tested
- Dietary Supplement, Control group (placebo)
- Keywords
- Parkinson's disease, REM sleep behavior disorder, inflammation, nutrition
- Medical subject headings
- Parkinson Disease, REM Sleep Behavior Disorder, Inflammation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dietary SupplementDietary supplement
L-theanine supplementation combined with Mediterranean diet for 4 weeks.
Control group (placebo)Other
Placebo combined with Mediterranean diet for 4 weeks.
| Study group | Role | What they receive |
|---|---|---|
| L-Theanine + Mediterranean Diet | Experimental | 200 mg of L-theanine supplement will be given daily. A Mediterranean diet will be followed. Receives: Dietary Supplement: Dietary Supplement |
| Placebo + Mediterranean Diet | Placebo comparator | 200 mg of placebo corn starch will be given daily. A Mediterranean diet will be followed. Receives: Other: Control group (placebo) |
What is being measured
The primary outcome is the main question the study is designed to answer.
RBD Screening Questionnaire (RBDSQ) score
Change in RBD Screening Questionnaire (RBDSQ) score from baseline to week 4. RBDSQ is a 13-item self-reported questionnaire assessing REM sleep behavior disorder symptoms. Scores range from 0 to 13; higher scores indicate greater RBD severity.
Measured: from baseline to week 4
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Jul 2026
- Study start2 May 2026
- Primary completion25 Sep 2026 (estimated)
- Study completion20 Oct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Parkinson Disease (PD)Studies of the same condition, open and under way.
- More trials run by Medipol UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 52 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Medipol University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Rüken Aslınur Samanci, Medipol University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07682532
- Sponsor's protocol ID
- 125S555
- Status last verified
- May 2026
- First submitted
- 28 Jun 2026
- Last updated
- 6 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- THE EFFECT OF L-THEANINE SUPPLEMENTATION ON REM SLEEP BEHAVIOR DISORDER, GASTROINTESTINAL FUNCTION, AND INFLAMMATORY MARKERS IN PARKINSON'S DISEASE
- ClinicalTrials.gov ID
- NCT07682532
- Acronym / sponsor ID
- 125S555
- Conditions
- Parkinson Disease (PD)
- Keywords
- Parkinson's disease, REM sleep behavior disorder, inflammation, nutrition
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 52 participants (estimated)
- Lead sponsor
- Medipol UniversityUniversity, hospital or other
- Study start
- 2 May 2026 (actual)
- Primary completion
- 25 Sep 2026 (estimated)
- Study completion
- 20 Oct 2026 (estimated)
- First posted
- 6 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Parkinson's disease is a progressive neurological disorder associated with severe dopaminergic neuron loss in the substantia nigra pars compacta. The decrease in dopamine cells in the gut in Parkinson's disease negatively affects bowel movements, and constipation is a common condition. Impairment of the intestinal barrier increases inflammation. Reactive oxygen species increase, and intestinal homeostasis changes. Alpha-synuclein levels increase in the gut. L-theanine is the most abundant amino acid in green tea leaves. Parkinson's patients exhibit increased oxidative stress along with decreased activity of glutathione peroxidase, superoxide dismutase, and catalase. L-theanine is believed to increase the activity of these enzymes and reduce oxidative stress. L-theanine administration has been found to increase total short-chain fatty acids in stool. Furthermore, it is suggested that L-theanine inhibits imbalances in oxidative stress and inflammatory responses by reducing inflammatory factors such as TNF-α, IL-6, and IL-1β. REM sleep disturbance is also a common problem in Parkinson's disease. Studies have shown that following L-theanine treatment, participants' Pittsburgh Sleep Quality Index (PSQI) scale scores improved. The gut microbiota regulates sleep and neurological states via the microbiota-gut-brain axis. L-theanine supplementation appears to be able to regulate gut bacterial composition to suppress neurotransmitters, cytokines, and other metabolites to regulate sleep. The protective effects of L-theanine administration on increased dopamine and other neurotransmitters, microbiota, sleep, and antioxidant enzymes may offer a glimmer of hope regarding its beneficial role in Parkinson's disease.
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| L-Theanine + Mediterranean Diet | Experimental | Dietary Supplement: Dietary Supplement200 mg of L-theanine supplement will be given daily. A Mediterranean diet will be followed. |
| Placebo + Mediterranean Diet | Placebo comparator | Other: Control group (placebo)200 mg of placebo corn starch will be given daily. A Mediterranean diet will be followed. |
Who may qualify
- Ages
- 50 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Patients diagnosed with Parkinson's Disease and classified as stage 1 according to the Hoehn-Yahr Staging (HYA), Patients without communication impairment (aphasia) Participants who sign the Informed Consent Form and volunteer to participate in the study Absence of dementia and Mini Mental State Examination (MMSE) score > 24 Living in the same household with a healthy spouse/partner Not taking prebiotic, fiber, probiotic, herbal, or high-dose vitamin or mineral supplements that may affect inflammation during the pre-onset period and throughout the study protocol
Key exclusion criteria (2 listed)
- Patients with a history of severe heart, lung, liver, or kidney failure, primary psychiatric, developmental, or other neurological disease Patients using sedative/hypnotic medications Individuals consuming more than 200 mg of caffeine per day (approximately 2-3 cups of tea or 1 cup of coffee) Patients who smoke and consume alcohol Having undergone surgery related to bowel health Having a chronic infectious bowel disease Having a congenital bowel anomaly Using probiotics, antifungals, and/or antibiotics within the last three months Individuals with an autoimmune disease or weakened immune system Self-reported alcohol or drug use within the last 3 months Current use of over-the-counter medications, supplements, foods, and/or beverages that may affect stress, sleep, cognition, and/or mood Inability to swallow the study supplement due to swallowing anxiety Receiving treatment for a GI disease or condition diagnosed by a doctor other than constipation, gastroparesis, gastroesophageal reflux disease, or diverticular disease Positive results for human immunodeficiency virus (HIV) or Hepatitis B/C. Current history of active conditions of inflammatory bowel disease, irritable bowel syndrome, colitis, celiac disease, short bowel syndrome, colostomy, colectomy, gastrointestinal fistula, or strictures.
- Recent or current use of any antibiotic (within 4 weeks prior to the start of the study) Use of enemas or suppositories to relieve constipation Good adherence to the Mediterranean diet in the pre-start period according to the 14-item Mediterranean Diet Assessment Tool (score >6)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dietary SupplementL-theanine supplementation combined with Mediterranean diet for 4 weeks. | Dietary supplement | L-Theanine + Mediterranean Diet |
| Control group (placebo)Placebo combined with Mediterranean diet for 4 weeks. | Other | Placebo + Mediterranean Diet |
Primary outcome
RBD Screening Questionnaire (RBDSQ) score
Time frame: from baseline to week 4
Change in RBD Screening Questionnaire (RBDSQ) score from baseline to week 4. RBDSQ is a 13-item self-reported questionnaire assessing REM sleep behavior disorder symptoms. Scores range from 0 to 13; higher scores indicate greater RBD severity.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jul 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Dietary Supplement in people with Parkinson Disease (PD), run by Medipol University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 6 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Rüken A Samancı (+90 543 939 15 94, rasamanci@medipol.edu.tr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
RBD Screening Questionnaire (RBDSQ) score (time frame: from baseline to week 4). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Jul 2026.