It appears scientists may have finally found the answer to that age-old question: Just how much coffee is too much coffee? Millions of Americans rely on that first cup of joe to kick-start their days. And over the past decade, the FDA and the Dietary Guidelines for Americans have advised not consuming more than 400 milligrams of caffeine in a 24-hour period.
While 400 milligrams is roughly the amount of caffeine in four cups of brewed coffee, the actual caffeine content in beverages can vary immensely, especially in specialty drinks. In the most extensive study of its kind, researchers from the University of South Australia discovered that consuming excessively high quantities of coffee is associated with smaller total brain volumes and an increased risk of dementia. The team published its findings in Nutritional Neuroscience, an international journal on nutrition, diet, and the nervous system.
According to the article, the team conducted analyses of 398,646 UK Biobank participants with ages ranging from 37 to 73. All the participants had information on habitual coffee consumption. Of these test subjects, 17,702 had MRI information, which was used to examine overall brain volume.
The study found that people who drank more than six cups of coffee per day had a 53% increased risk of developing dementia over time compared with those who drank one to two cups per day.
“Coffee is among the most popular drinks in the world,” Kitty Pham, a researcher, said in a statement to the University of South Australia. “Yet with global consumption being more than nine billion kilograms a year, it’s critical that we understand any potential health implications.”
The study is the largest to date to examine measurements of brain volume together with “a wide range of confounding factors,” and how these relate to coffee consumption and the risks of either dementia or stroke.
“Accounting for all possible permutations,” Pham said, “we consistently found that higher coffee consumption was significantly associated with reduced brain volume — essentially, drinking more than six cups of coffee a day may be putting you at risk of brain diseases such as dementia and stroke.”
Dementia primarily affects older adults, according to the US Centers for Disease Control and Prevention, and it is not a specific disease. Rather, dementia is a general term for the impaired ability to remember, think, or make decisions about everyday activities.
“This research provides vital insights about heavy coffee consumption and brain health, but as with many things in life, moderation is the key,” said Elina Hyppönen, senior investigator and director of the University of South Australia’s Centre for Precision Health. “However, if you’re finding that your coffee consumption is heading up toward more than six cups a day, it’s about time you rethink your next drink.”
While this study found no direct correlation between developing dementia or stroke and moderate coffee consumption, the findings are some of the first to specify a precise limit on daily coffee consumption.