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An expiration date on green tea’s antioxidants?

Molding, rotting, bruising, stinking…These are reasons I avoid letting food sit too long before preparing or eating it. But how about losing antioxidants? Turns our some foods may not be worth eating even if they don’t appear to be spoiled. Recent studies show that antioxidants in green tea and olive oil significantly decrease the longer you store them.

Research from the USDA’s Western Regional Research Center showed commercial green tea progressively lost catechin antioxidants—which have been shown to have antibacterial and virus-fighting abilities and which may help inhibit cancer cells—as time went on. After six months, the antioxidant powerhouse lost an average of 32 percent of its antioxidants, which the researchers classify as highly significant. An Italian study from the University of Foggia showed similar results for extra-virgin olive oil, which lost 40 percent of its antioxidants after six months. In fact, all plant foods—even packaged ones—depreciate over time.

Although this might surprise a lot of people who would expect that if something stays sealed it will not lose nutritional value, antioxidants are very fragile. And, of course, in general, it is well known that when we look at plant foods as a whole, the nutritional value is best the fresher it is.

Now there’s no getting around it: Clean up that pantry! And rethink your buying habits. For some items, like tea, try shopping in your grocery store’s bulk foods department, which refills bins regularly. Buying what you know you’ll use (immediately or in the near future) helps save money, reduce waste, and maintain a fresh supply. To preserve antioxidants longer, keep olive oil in small glass bottles in dark environments and store tea in tinted containers to protect it from the sun.

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