Does Glutathione Help in Preventing Cancer?
No, glutathione supplementation is not recommended for cancer prevention, and the best advice is to obtain antioxidants through food sources rather than supplements. 1
Evidence from Cancer Prevention Guidelines
The American Cancer Society has consistently stated across multiple guideline iterations that while antioxidants (including glutathione) found naturally in vegetables and fruits are associated with lower cancer risk, clinical studies of antioxidant supplements have not demonstrated a reduction in cancer risk. 1
Key Guideline Recommendations:
Studies suggest that people who eat more vegetables and fruits, which are rich sources of antioxidants, have a lower risk for some types of cancer. 1
However, clinical studies of antioxidant supplements are currently underway, but studies have not yet demonstrated a reduction in cancer risk from vitamin supplements. 1
To reduce cancer risk, the best advice presently is to consume antioxidants through food sources rather than supplements. 1
The Paradoxical Role of Glutathione in Cancer
The relationship between glutathione and cancer is complex and context-dependent:
Protective vs. Pathogenic Roles:
Glutathione metabolism can play both protective and pathogenic roles with respect to cancer. 2
While GSH is crucial in the removal and detoxification of carcinogens, elevated levels of glutathione in tumor cells are able to protect cancer cells and confer resistance to chemotherapeutic drugs. 2, 3
Excess glutathione promotes tumor progression, where elevated levels correlate with increased metastasis. 3
Cancer Treatment Considerations:
During cancer treatment, most oncologists advise against taking higher doses of supplements with antioxidant activity during chemotherapy or radiotherapy because antioxidants could repair cellular oxidative damage to cancer cells that contributes to the effectiveness of these treatments. 1
Six small randomized trials evaluated glutathione against platinum-based neurotoxicity, with mixed results—five showed benefit for neuropathy reduction, but one larger trial failed to demonstrate benefit for taxane-induced neuropathy. 1
Dietary Sources vs. Supplementation
The evidence consistently supports obtaining glutathione and other antioxidants through whole foods rather than supplements:
Freshly prepared meats are relatively high in glutathione, fruits and vegetables have moderate to high amounts, while dairy products, cereals, and breads are generally low. 4
Processing and preservation generally result in extensive loss of glutathione from foods. 4
Clinical Bottom Line
For cancer prevention, focus on consuming at least five servings of vegetables and fruits daily rather than taking glutathione or other antioxidant supplements. 1 The protective effects observed in epidemiological studies are associated with whole food consumption, not isolated antioxidant supplementation, and there is potential for harm from disrupting the delicate balance of oxidative stress that the body uses to eliminate abnormal cells.