glutathione process The redox cycle, demonstrating the inter-conversion of Try This: The Power of
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The Emerging Hallmarks of Cancer Metabolism

People use them because they are cheap and easy to access

Verma V, Ravindran P, Kumar PP (2016) Plant hormone-mediated regulation of stress responses

I feel better and have less pain
Long-term human safety data is still more limited than for well-established supplements like vitamin C, so periodic doctor check-ins are a reasonable precaution