How does your daily consumption stack up?

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More than 7 in 10 Americans drink coffee daily, averaging about three cups per day, according to the National Coffee Association. At that rate (and at the right time of day, AKA not too close to bedtime), coffee acts as a pick-me-up that offers a surprisingly wide range of health benefits.

But new research published June 2021 in the journal Nutritional Neuroscience proves that—like with most things in life—there can be too much of a good thing. After diving into 8 to 12 years of data collected about the coffee habits of more than 398,000 adults enrolled in a British study, the Australian research team discovered that sipping more than six cups of coffee per day was associated with a 53% increased risk of dementia and a smaller brain volume.

So while coffee can be good to give you a little energy buzz, it can be not so great for your brain health—if you consume it in large quantities. Those who reported drinking more than six cups daily had "notable increases" in the odds of dementia, the researchers say, or about 53% higher than their peers who drank one to two cups per day. (Tea drinkers didn't seem to experience any detrimental effects, the researchers say.)

These findings held true even after the scientists accounted for lifestyle variations and other factors, and were found among both men and women at a wide variety of ages. The more java people drank over six cups per day, the more brain shrinkage they experienced, as determined by MRI scans.

The study authors concede that this doesn't necessarily mean that the coffee leads to brain shrinkage or dementia, but the factors are correlated. They also monitored stroke risk as it related to high coffee consumption, and found no evidence of a connection there.

senior woman making coffee in the kitchen at home.
Credit: Getty Images / Halfpoint Images

While all humans experience some reduction in brain volume over time, quicker and higher amounts of brain volume loss could lead to earlier dementia.

Since the caffeine in coffee allows it to cross the blood-brain barrier, a cup can make you feel more alert, assist with concentration, boost mood and reduce feelings of depression, according to another study in the journal Practical Neurology. And in moderation, coffee has been linked to a longer life, less risk for heart disease and a healthier liver.

But all those benefits seem to max out at about two to four cups daily when you're talking about your brain. (Yes, even taking into account the fact that coffee is the top source of antioxidants for Americans.)

Elina Hypponen, study co-author and director of the Australian Centre for Precision Health at the University of South Australia Cancer Research Institute, tells TODAY that their study results didn't offer enough information for them to quantify exactly how much is too much. The findings do suggest that keeping caffeine intake to 300 milligrams or less per day (about four, 8-ounce cups) is probably best. Keep in mind that most mugs found in U.S. kitchens typically hold between 12-16 ounces.

Drinking water alongside every cup of coffee also can't hurt, Hypponen adds, to potentially stave off the caffeine-related dehydration that may have a harmful effect on the brain. And with that H2O and coffee, might we recommend fueling up with these best foods for brain health?