Glutathione Study Reveals How Cancer Exploits Antioxidants

A University of Rochester team has uncovered a previously underappreciated way that cancer cells use the antioxidant glutathione as a nutrient source, suggesting new possibilities for targeting tumor metabolism. Their findings were reported in Nature.

Glutathione is produced naturally in the body and is also available as a popular antioxidant supplement. Traditionally, research has focused on its ability to prevent or repair cellular damage. In contrast, a team led by Isaac Harris has been investigating how glutathione can act as a “pro-tumor” nutrient. “Cancer cells and normal cells potentially use different food sources,” Harris explained, “and we discovered how cancer cells, specifically, break down this antioxidant and use it as fuel.” This work builds on earlier findings from the Harris lab and collaborators showing that a whole-food plant-based diet may reduce certain pro-tumor nutrient sources in the body. 

The new study examined breast tumor samples donated to Wilmot’s Biobank. By isolating and analyzing the fluid inside the tumors, the researchers found high levels of stored glutathione, indicating that tumors are actively consuming it as a nutrient. In preclinical breast cancer models, the team was able to slow tumor growth by blocking the cancer cells’ ability to use glutathione. Harris noted that preliminary data suggest many other tumor types may also rely on glutathione in a similar way.

The findings fit into a broader re-evaluation of how antioxidants interact with cancer. Harris pointed out that substances commonly viewed as benign or beneficial can be “hijacked” by cancer cells. For example, colleague Jeevisha Bajaj recently reported that taurine, another antioxidant found in foods, supplements, and energy drinks, can drive leukemia growth. Harris emphasized that these results do not mean people should avoid antioxidant-rich whole foods; rather, he cautioned against high-dose, unregulated antioxidant supplements, particularly glutathione, which “can present risks.”

To move their discoveries toward clinical application, the team used advanced technology to search for compounds that could inhibit tumor use of glutathione. They identified an existing drug developed nearly a decade ago. Chemist Tom Driver and metabolism expert Joshua Munger are working on strategies to refine this compound and identify the precise proteins that channel glutathione into tumors. Future plans include testing combinations of anticancer drugs along with dietary interventions. The overarching goal, Harris said, is to create therapies that effectively kill tumors while sparing healthy cells, noting that “even though glutathione was discovered 100 years ago, we are finding completely new aspects to its biology.”