“Taking a pill that is unregulated by the FDA and has a high concentration of glutathione can present risks.” The warning comes from Isaac Harris, a cancer researcher at the University of Rochester, and it lands on a supplement sold everywhere as a protector.
Glutathione is an antioxidant. The body makes it naturally, and you can also buy it off the shelf as a dietary supplement, usually with health claims attached. For years, scientists who studied it focused on how it prevents or repairs cell damage. Harris and his team looked at the other side of it.
What the lab found
Their study appeared in Nature on March 18. Fabio Hecht and Marco Zocchi did the hands-on work in Harris’s lab. The finding: cancer cells can break glutathione down and burn it as fuel. Tumors usually sit in tissue where nutrients are scarce, so they are good at finding food wherever it is.
“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.”
To test the idea, the researchers examined breast tumor samples donated to Wilmot’s Biobank. Fluid taken from inside the tumors held a large store of glutathione, which suggests the tumors were eating it. In preclinical models of breast cancer, cutting off the tumor’s ability to use glutathione slowed its growth. Early data point to the same pattern in many other tumor types.
Why it matters for supplement buyers
Harris was careful about what this does not mean. Nobody should drop fruit and vegetables. “Eating a balanced diet with fruits and vegetables is important,” he said. “It can control weight, reduce inflammation, and support a healthy immune system.” His caution is aimed at pills, particularly glutathione.
The laboratory has seen the double edge of antioxidants before. Last year Jeevisha Bajaj, a colleague of Harris, reported in Nature that taurine, another antioxidant, found in food, supplements and energy drinks, fuels leukemia cell growth. “It’s important to understand how cancer hijacks certain substances that we may think of as harmless,” Harris said. The National Cancer Institute has also urged caution on how nutrients and supplements relate to cancer.
Put plainly, a molecule many people assume is harmless turns out to be something tumors eat. Anyone thinking of taking glutathione should talk to a doctor first.
A possible drug
The team also searched for ways to block the process and found a promising candidate, a drug first developed nearly a decade ago. Chemist Tom Driver and biochemist Joshua Munger, both at Rochester, are working to improve it and to identify which proteins let tumors process glutathione. Future work will test anticancer drugs alongside diet changes.
“Even though glutathione was discovered 100 years ago, we are finding completely new aspects to its biology,” Harris said.
Sources
- Scientists Discover an Unexpected Food Source for Tumors
- Why is this supposedly protective antioxidant now intriguing cancer researchers?
