The results of a recently published study are particularly striking. It followed almost 1,000 older adults in China over a period of seven years, and found those who drank at least one cup of tea a day were 50 percent less prone to cognitive deterioration.
Those who carry the APOE4 gene fared even better. They were 85 percent less likely to show a loss of brain function. That's important because the APOE4 gene is tied to higher risk for Alzheimer's and other forms of dementia.
Impressive as those results are, they do not surprise Dr. Yuko Hara, acting director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Her organization evaluates foods, beverages, vitamins and supplements for their ability to promote brain health and publishes its findings on the Cognitive Vitality website.
Hara says when it comes keeping your mind sharp, green tea looks to be a particularly good choice.
"Overall, I think we have about 40 reports (on the Cognitive Vitality site) and green tea may be one of the most promising things we've analyzed for brain health so far," she says. "Based on what I've seen, green tea does look the most promising."
That ringing endorsement doesn't mean green tea can actually prevent Alzheimer's or be used to treat people who have it.
But we're learning more every day about healthy lifestyle choices that can reduce our risk of Alzheimer's, and even potentially slow cognitive decline in people who are showing early signs of memory loss.
Better yet, these healthy habits often are low-cost and easy to adopt. Drinking tea is a prime example of that. It's affordable enough and available enough to rank as the second most consumed beverage in the world (after water).
As a potential source of brain health, it's also among the most researched. The Cognitive Vitality report on green tea references more than a dozen studies or other resources that address the health benefits of tea.
Many are what's called observational studies, which look at a group of people over a period of time to find connections between lifestyle behaviors and health outcomes. "There have been many observational studies that associate greater green tea intake with lower dementia risk," Hara says. "But that's not all there is for green tea in terms of scientific evidence."
Hara says observational studies don't provide proof of a health benefit, because other factors could influence the results. The most authoritative research comes from doing a double-blind, randomized control trial -- what Hara calls the "gold standard" in scientific research.
One such study on green tea published in 2011 delivered noteworthy results. It involved 91 people with mild cognitive impairment who were given a green tea extract and an amino acid called L-theanine for 16 weeks. At the end of that period, these people showed major improvement in memory and attention, and the benefit was particularly noticeable in those who began with the greatest memory impairment.
"That's what's exciting about green tea," Hara says. "It has clinical evidence and studies in humans, but then it also has this gold-standard trial showing that it does improve memory."
Researchers aren't sure exactly why green tea is so good for the brain. But Hara, who holds a Ph.D. in neurology and neuroscience from the Weill Graduate School of Medical Sciences at Cornell University, says green tea contains several compounds that seem to enhance brain health. They include:
Tea isn't the only popular beverage known to promote brain health. Coffee is good for your mind, too. I wrote about that in a column last fall, and Cognitive Vitality also has a report on coffee, which you can read here.
Cognitive Vitality gives both coffee and green tea a rating of three brains in its scale of potential benefit for benefit. That's the highest score it gives any food, beverage or supplement it's evaluated so far.
The Cognitive Vitality website rates green tea high for both potential benefit and safety. You can read the full report on green tea here.Courtesy of ADDFStill, between coffee and tea, Hara rates the latter as first among equals. "I think green tea has an edge over coffee," she says, "because coffee doesn't contain EGCG or L-theanine."
Someday, Hara and her colleagues would be glad to award a rating of four brains on their site, but that status is reserved for something proven to actually prevent dementia. We don't have anything like that right now.
Until we do, the best strategy is to embrace behaviors that reduce our risk. For that, green tea is not only a good choice, but based on every scientific measure so far, one of our best choices.
"There's promise with green tea," Hara says. "We don't want to oversell something, but if there's enough research showing benefits across a number of studies, we give it a three. Three brains is as good as it gets."
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