Recruiting · registry statusStudying diet and a supplement for sleep and gut symptoms
Researchers study L-theanine and a Mediterranean-style diet in relation to dream-sleep movements, digestive function and inflammation in Parkinson’s.
Testing a treatment or activity · Study reference: NCT07682532
Plain-language introduction written with AI from the registry; not independently checked by a clinician. Read the original details below ↓
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Looking for volunteers
- Start (reported actual date)
- 2026-05-02
- Main measurements finished (planned)
- 2026-09-25
- Study finished (planned)
- 2026-10-20
Planned dates can move. A study finishing does not tell us when a paper will be published.
No results summary has been confirmed in the registry records we imported. See connected papers below; we keep checking after recruitment ends.
Changes we have recorded
These are dates we observed a change, not necessarily the dates it happened.
Papers connected to this study
No connected paper has been found yet. The tracker checks the growing library for study identifiers and registry-linked publications.
Who can join?
Ages 50 years to 80 years · Does not accept healthy volunteers
These are starting points, not the full rules. The research team can tell you whether the study is right for your situation.
Read all the rules for taking part
Sex eligibility reported by registry: all
Inclusion Criteria:
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
Exclusion Criteria:
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)
Full study name & original research details
Official study title
THE EFFECT OF L-THEANINE SUPPLEMENTATION ON REM SLEEP BEHAVIOR DISORDER, GASTROINTESTINAL FUNCTION, AND INFLAMMATORY MARKERS IN PARKINSON'S DISEASE
Short title used by the registry
L-THEANINE AND MEDITERRANEAN DIET ON RBD, GI FUNCTION, AND INFLAMMATION IN PARKINSON'S DISEASE
Original description
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 reported: Parkinson Disease (PD)
Registry records for this study
Records are joined using registration identifiers. Titles alone do not establish that two studies are the same.
- Study type
- Interventional
- Interventions
- Dietary Supplement; Control group (placebo)
- Phases
- NA
- Sponsor
- Medipol University
- Start date reported by registry
- 2026-05-02 (actual)
Registry updated: 2026-07-06 · Status last verified by the registry submitter: 2026-05
Registry records retrieved 2026-10-11 (UTC). Individual records may have older updates. Recruitment and eligibility must be confirmed with the study team.
Contact the research team
Public study contacts supplied to the registry. Ask whether recruitment is still open and what participation involves.
Rüken A Samancı · +90 543 939 15 94 · rasamanci@medipol.edu.tr
Study locations
Site status can differ from overall study status. “Status not reported” means local availability needs confirmation. Remote participation and travel arrangements must be checked with the team.
Medipol Mega Hospital
Istanbul, Turkey (Türkiye)
RecruitingRüken A Samancı · +90 543 939 15 94 · rasamanci@medipol.edu.tr
Gözde Ülfer
Eren Toplutaş
Facility not reported
Turkey (Türkiye)
Status not reportedThe original descriptions and participation rules come from the registry. Participation is voluntary and does not guarantee benefit.