A study reveals that a popular antioxidant supplement may feed cancer cells and accelerate tumors

The discovery that glutathione, a widely promoted antioxidant supplement as healthy, can serve as fuel for cancer cells was announced by the Wilmot Cancer Institute of the University of Rochester. Glutathione, considered for decades the “master antioxidant”, turns out to be vulnerable to catabolism by tumor cells, which break it down and use it as an alternative source of nutrients —mainly cysteine—, which favors their growth and survival in resource-poor environments. This implies that high-dose supplementation, far from protecting, could stimulate tumor progression, leading experts to advise extreme caution in its consumption and to reconsider new treatment pathways to block this process. The team at the Wilmot Cancer Institute, led by Dr. Isaac Harris and composed of doctors Fabio Hecht, Marco Zocchi, Tom Driver, and Joshua Munger, is responsible for this finding, published in Nature. According to bioengineer.org and rochester.edu, the study combines analysis of human samples and experimental models of breast cancer, and demonstrates that tumor cells subjected to environmental stress use the glutathione available in their environment to meet their demand for amino acids.

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The Tumor Metabolism of Glutathione

Cancer cells exhibit remarkable metabolic flexibility. In the absence of nutrients, they can utilize extracellular glutathione as a source of amino acids, highlighting cysteine. This antioxidant, composed of glutamate, cysteine, and glycine, is degraded by gamma-glutamyltransferase enzymes, which allows tumors to use its components and ensure their growth even when other pathways are blocked by drugs, as detailed by researchgate.net. Research shows that high doses of glutathione supplements can become a key source of cysteine for the metabolism of solid tumors (Photo: Canva) According to tun.com, the dependence on glutathione reinforces tumor resistance. If its catabolism is interrupted, as revealed by Harris’ experiments, tumor expansion slows down considerably, while normal cells depend less on this pathway and are not as affected.

New therapeutic pathways and pharmacological approaches

This discovery identifies a vulnerability in tumor metabolism. The team, according to rochester.edu and biocompare.com, explores glutathione inhibitors to selectively slow the advance of cancer, seeking targeted solutions that do not compromise healthy tissues. Chemist Tom Driver and biochemist Joshua Munger optimize molecules capable of blocking the absorption of glutathione by tumor cells. They are working on the refinement of existing compounds, with the goal of combining them with classic treatments and overcoming the resistance of aggressive tumors, as reported by tun.com and biocompare.com. In that sense, simultaneously attacking several metabolic feeding pathways could improve efficacy and limit adverse effects.

Dangers of consuming antioxidant supplements

The study, reported by medicaldialogues.in and knowlridge.com, distinguishes between the natural intake of antioxidants and the consumption of supplements in high doses. “People should be cautious when taking supplements in general, particularly glutathione. Taking a pill that is not regulated can present risks,” details Dr. Harris, according to statements to rochester.edu. The work led by Dr. Isaac Harris highlights the importance of rethinking the use of antioxidants in patients with breast cancer and other tumor variants. Different medical sources emphasize that consuming fruits and vegetables rich in antioxidants poses no danger, but resorting to exogenous and concentrated supplements, especially by cancer patients, could favor tumor nutrition and hinder the effectiveness of treatments. Experts conclude that the key is to avoid the indiscriminate use of antioxidant supplements and always consult with professionals before incorporating them into the diet.

Implications for Different Cancer Types

The experimental core of the research focused on breast cancer, but, according to rochester.edu and eltiempomx.com, researchers suggest that this mechanism could be present in other solid tumors. You can also read: Students and scientists at Wilmot are exploring whether tumor antioxidant metabolism operates similarly in various organs and cancer subtypes, including aggressive variants with limited therapeutic options. The next steps involve developing therapies that target these alternative nutrition pathways, seeking universal vulnerabilities in cancer biology. Advancing the understanding of how tumors obtain hidden nutrients is the first step in designing interventions capable of blocking their metabolic sources and weakening their progression. Identifying and closing these internal “eaters” is crucial to limit the resources of cancer and curb its growth.