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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
SINGLE
Enrollment
52
L-theanine supplementation combined with Mediterranean diet for 4 weeks.
Placebo combined with Mediterranean diet for 4 weeks.
Medipol Mega Hospital
Istanbul, Turkey (Türkiye)
RECRUITINGRBD 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.
Time frame: from baseline to week 4
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