Green Tea Isn't an Antioxidant After All (But It's Still Good for You)

Green tea has long been touted as the elixir of youth—high concentrations of chemicals called polyphenols were believed to have powerful antioxidant effects, promoting wellness. 

However, a new study has revealed new, contradictory insights on green tea’s impact on a cellular level. Previously, polyphenols were thought to dampen oxidative stress or the accumulation of potentially damaging free radicals produced as a byproduct of metabolism. Now, Michael Ristow and researchers from ETH Zurich say polyphenols temporarily elevate levels of oxygen free radicals instead. 

Does this mean you should put that matcha latte down? No, suggest the results of the study published in the journal Aging, which say that these biochemical changes triggered by polyphenols boost the immune system. 

“That means green tea polyphenols, or catechins, aren’t in fact antioxidants, but rather pro-oxidants that improve the organism’s ability to defend itself, similar to a vaccination,” said Ristow. 

In their study, the scientists used a worm model to study the effect of polyphenols on longevity. They found that by supplementing the nematodes’ diet with green tea catechins, they lived longer and were more resistant to disease. 

The team identified that these effects were due to the activation of enzyme-producing genes that eliminate free radicals. Exposure to polyphenols ramped up the production of superoxide dismutase and catalase in the worms.

According to the researchers, the results observed in nematodes should mirror those that we can expect to see in humans—the biochemical pathways involved in eliminating free radicals in cells have been conserved across millions of years of evolution.

Interestingly, the authors say that the same reduction in oxidative stress can be achieved through calorie restriction. A 2009 study led by Ristow showed that mice on a calorie-restricted diet lived longer than those that ate a regular, high-calorie diet.