**Definition:**  

Glutathione (GSH) is a tripeptide composed of three amino acids: glutamine, cysteine, and glycine. It is a potent antioxidant naturally produced in the human body and found in various foods. Glutathione exists in two forms: reduced (GSH) and oxidized (GSSG), with the reduced form being the active antioxidant.

**Functions:**  

1. **Antioxidant Properties:** Glutathione neutralizes free radicals, protecting cells from oxidative stress and damage.  

2. **Detoxification:** It plays a key role in detoxifying harmful substances, including heavy metals and environmental toxins, by binding to them and facilitating their excretion.  

3. **Immune Support:** Glutathione enhances immune function by promoting lymphocyte activity and reducing inflammation.  

4. **Cellular Repair:** It aids in DNA synthesis and repair, contributing to overall cellular health.  

**Applications:**  

1. **Pharmaceuticals:** Used in supplements and medications to support liver health, combat oxidative stress, and boost immunity.  

2. **Cosmetics:** Incorporated into skincare products for its anti-aging and brightening effects, reducing pigmentation and improving skin texture.  

3. **Food Industry:** Added to functional foods and beverages to enhance nutritional value and promote detoxification.  

4. **Healthcare:** Applied in clinical settings to treat conditions like Parkinson's disease, Alzheimer's, and chronic fatigue syndrome.