Green tea has already been shown to help slow down Alzheimer's disease, ease anxiety, helping with weight loss, and even prevent cancer. Now, a groundbreaking new study shows that green tea also sharpens memory – almost immediately after consuming it.

Swiss researchers gave a group of healthy guys either a beverage containing 27.5 grams of green tea extract or a dummy drink. Next, the men completed a series of tasks designed to gauge their working memory, while the researchers examined their brain activity using magnetic resistance imaging, or MRI. Overall, the green tea drinkers performed better on the memory tests than the placebo group. The MRIs revealed why: Their parietal lobe (which processes sensory information into words and thoughts) and their frontal lobe (responsible for decision making and problem solving) were better able to communicate with each other. Basically, by increasing the amount of back-and-forth between these two brain regions, green tea boosted these guys' ability to remember information.

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The fact that green tea offers cognitive benefits isn't all that surprising – but that it can enhance memory so quickly is a huge discovery. "Most research on green tea consumption and its effects on the development of Alzheimer's disease and other cognitive issues have been long-term, observational studies," says Liz Applegate, director of sports nutrition at the University of California at Davis, who was not involved with this research. "But this study looked at the acute effects of green tea extract using an imaging technique that gives a snapshot of brain activity. That makes these findings look very legit – and very compelling."

Although the study authors aren't clear on exactly how green tea improves communication within the brain, Applegate thinks it has a lot to do with the amino acid theanine, found only in green tea. She says several studies have shown that this compound boosts brainpower in animals, so it's highly likely that it has the same effect on humans. She also points out that, along with theanine, green tea contains a host of catechins, namely ECGC, as well as caffeine. Individually, all of these compounds have proven cognitive benefits, says Applegate, but when combined in green tea, they may work synergistically to be even more effective.

To ensure that you're getting green tea's full brain-boosting power, your best bet is to brew it yourself. "The amount of active compounds in green tea really depends on brewing time and temperature," Applegate says. "So take the time to brew up a big pitcher and take some with you wherever you go. Remember, too, that regular tea drinkers have lower body-mass indexes and reduced risk of cancer and heart disease."