The best way for most people to boost glutathione is through their diet, Ms. King added. Foods like poultry, eggs and lentils, as well as cruciferous vegetables like broccoli, cauliflower and brussels sprouts, are especially high in sulfur, she said, which naturally increases glutathione production.
Could it make you sick?
There’s a strange paradox when it comes to antioxidants and cancer. While antioxidants produced in the body can neutralize the oxidative stress that contributes to cancer development, consuming them in supplement form has been associated with an increased risk of cancer in some cases.
Doctors do not allow any antioxidant supplements, including vitamin C or vitamin E, during anticancer treatment, Dr. Li said, because regimens like chemotherapy work by increasing oxidative stress to destroy cancerous cells. Taking antioxidants could “salvage” those cells, she added.
Several studies have examined whether antioxidant supplements could help prevent cancer, with the majority showing no effect. A long-term trial investigating whether two antioxidant supplements — vitamin E and selenium — could prevent prostate cancer was stopped early because neither was found to be effective initially, and a follow-up study found a significant increase in cases among participants who took vitamin E only. More recently, a study published earlier this year found that breast cancer cells in mice could “hijack” glutathione and use it as fuel to grow, said Dr. Harris, who led the study. The cancer cells break the glutathione down into its three amino acid components and use one of them, cysteine, as a “lifeboat” to survive stressful conditions, including oxidative stress.
This doesn’t mean glutathione, or any other antioxidant, causes cancer, Dr. Harris said. But, he added, it is “potentially risky” to take glutathione supplements when you can get all you need by eating whole foods. More broadly, the National Cancer Institute has said that antioxidant supplements should be used “with caution” by cancer patients.
Other experts disagreed about the risks posed by glutathione. “I don’t see this as a red flag for using glutathione supplements,” said Dr. Eyal Gottlieb, a professor of cancer biology at the University of Texas MD Anderson Cancer Center in Houston. He said the rodent study was interesting, but that the results couldn’t be extrapolated to humans. Still, he added, he would not recommend glutathione supplements, because there wasn’t evidence to prove they were effective.