The goal of this study is to evaluate the safety and tolerability of Gamma Glutamylcysteine (GGC) supplement at different doses (400mg/day or 800mg/day or 1200mg/day) when administered orally to patients with MCI over 3 months. This study is designed to generate preliminary clinical safety data to inform the feasibility and design of larger controlled trials.

Oxidative Stress (OS) plays a key role in aging and neurodegenerative diseases, including Alzheimer's Disease. The brain's primary antioxidant, GSH, is essential for combating Reactive Oxygen Species (ROS).This study is designed as an open-label, single-center, dose escalation clinical trial to evaluate the safety and tolerability of GGC supplementation in patients with MCI. This will enable the investigators to identify maximum tolerated or recommended dose for further clinical evaluation.

Inclusion Criteria:

1. Memory complaints;
2. MCI diagnosis
3. MoCA score between 18-25
4. Age 55 - 80 years old.
5. Ability to read and write in English

Exclusion Criteria:

1. Subjects with acute head trauma or head injury involving loss of consciousness;
2. Subjects with a history of cancer;
3. Subjects with a history of schizophrenia, manic-depressive disorder
4. Subjects on antioxidant therapy (ashwagandha, gingko biloba, N-acetylcysteine or glutathione)
5. Subjects on illicit drug (cocaine, heroin, marijuana, or fentanyl) abuse/dependence;

De-identified individual participant data underlying the primary and secondary outcome analyses will be provided after the study data is analyzed and published. A comprehensive report will be sent to the IRB. The respective agency will be reported accordingly. Requests for the release of data must be submitted in writing to the PI, clearly stating the purpose of the request, the specific data needed, and the intended use. The PI, in collaboration with the research team, will review each request to ensure compliance with institutional policies, ethical standards, and any relevant data use agreements.