The study looked at the relationship of coffee and tea with the risk of dementia and stroke, finding that there is a certain number of cups per day that has the biggest association with decreased risk.

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Like to have a few cups of coffee or tea each day? It could help lower your risk of stroke and dementia.

That's the takeaway from a new study that's getting plenty of buzz. The study, which was published in PLOS Medicine on November 16, analyzed data from 365,682 people aged 50 years to 74 years who participated in the UK Biobank. (The UK Biobank, in case you're not familiar with it, is a large-scale biomedical database and research resource.) The participants' health, along with their coffee- and tea-drinking habits, were followed for a period of 10 to 14 years.

During the study period, 5,079 participants developed dementia and 10,053 participants had at least one stroke. The researchers compared people who didn't drink coffee or tea with those who drank the beverages regularly and found that those who like their brewed drinks had a lowered risk of stroke and dementia than abstainers. Specifically, those who had either two to three cups of coffee a day or three to five cups of tea a day had a lower risk of dementia and stroke. Those who had two to three cups of coffee a day and two to three cups of tea a day—so, in combination, four to six cups of coffee and tea a day—had the best results, with a 32% lower risk of stroke and 28% lower risk of dementia.

Coffee and Tea Decrease Dementia and Stroke Risk , coffee cup with brain icon, top view on background with sunlight.
Credit: Getty Images

"We found that drinking coffee and tea separately or in combination were associated with lower risk of stroke and dementia," the researchers wrote in the conclusion. "Intake of coffee alone or in combination with tea was associated with lower risk of poststroke dementia."

It's important to point out that the study found only an association, not causation. Meaning, the researchers didn't find that regularly drinking coffee or tea actually lowers a person's risk of dementia and stroke—just that people who tend to drink coffee and tea often have a lower risk of those serious health issues. Scott Kaiser, MD, a geriatrician and director of Geriatric Cognitive Health for the Pacific Neuroscience Institute at Providence Saint John's Health Center in Santa Monica, California, tells Health that the correlation vs. causation factor is key. He notes that the study, "does not prove that drinking coffee or tea actually caused this reduction in risk."

Still, doctors are intrigued. "I am excited that my personal risk of dementia might go down with coffee use," Amit Sachdev, MD, medical director in the Department of Neurology at Michigan State University, tells Health.

And this isn't the first study to find a positive link between coffee, in particular, and health. One study of more than 468,000 people presented at the European Society of Cardiology in August found that having up to three cups of coffee a day is linked to a lower risk of stroke and heart disease. A meta-analysis of data from 34,282 people published in the journal Clinical Nutrition in 2016 also found that having one or two cups of coffee a day is linked with a lowered dementia risk.

Of course, you can have too much of a good thing. A study published earlier this year in the journal Nutritional Neuroscience found that drinking more than six cups of coffee a day actually raises your dementia risk.

The "considerable controversy" that exists around the association of coffee and tea consumption with stroke and dementia is actually one of the reasons the researchers say they conducted this most recent study.

It's not entirely clear why there might be a link between your coffee and tea intake and your dementia and stroke risk—and the latest study didn't explore this. "While caffeine is certainly a key common denominator, coffee and tea are both derived from plants with many, many potentially beneficial chemical compounds, including powerful antioxidants," Dr. Kaiser says. Any of those so-called phytonutrients—ie, chemicals that plants produce to keep themselves healthy—"can actually reduce inflammation in our brains, protect brain cells from injury, support learning and memory, and deliver other obvious benefits for brain health," he explains.

All of this raises a huge question: If you're not a coffee or tea drinker, should you start? Dr. Sachdev doesn't recommend it. "I am a bit skeptical that this study should change behavior," he says. "I would be more interested if a particular compound in coffee or tea was identified."

But if you're already a coffee or tea drinker, you can feel good knowing that your regular routine might have an association with a lower risk of dementia and stroke.

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