Coffee may be the perfect morning pick-me-up, but a new study suggests drinking it in excess can compromise our brain health over time.
Researchers in Australia have found that high coffee consumption is associated with smaller total brain volumes and a 53 per cent increased risk of dementia.
The experts offer no explanation for the surprising link, which follows multiple previous studies that found drinking coffee in moderation can actually stave off dementia.
The new study also follows a wealth of prior evidence that drinking coffee does have other health benefits over time – as long as it’s not consumed in excess.
Although it was not specifically determined that excess coffee consumption caused dementia, the authors of this new study warn against high consumption of the black stuff, which they define as more than six cups a day.
The study, published in Nutritional Neuroscience, has been led by experts at the University of South Australia (UniSA), along with academics from other institutions including the University of Cambridge and the University of Exeter.
‘Coffee is among the most popular drinks in the world. Yet with global consumption being more than nine billion kilograms a year, it’s critical that we understand any potential health implications,’ said study author Kitty Pham at UniSA.
‘This is the most extensive investigation into the connections between coffee, brain volume measurements, the risks of dementia, and the risks of stroke.
‘It’s also the largest study to consider volumetric brain imaging data and a wide range of confounding factors.
‘Accounting for all possible permutations, 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.’
According to the European Food Safety Authority, we should be drinking 400mg of coffee a day – about four to five cups – at the very most although the daily maximum is only 200mg for pregnant women.
‘Typical daily coffee consumption is somewhere between one and two standard cups of coffee,’ said study author Professor Elina Hyppönen.
‘Of course, while unit measures can vary, a couple of cups of coffee a day is generally fine.
‘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.’
The experts assessed the effects of coffee on the brain among 17,702 UK Biobank participants, aged between 37 and 73.
Those who drank more than six cups of coffee a day had a 53 per cent increased risk of dementia compared with those who consumed one to two cups a day.
Drinking more than six cups of coffee was also associated with a 17 per cent increased risk of having a stroke.
About 50 million people are diagnosed with dementia worldwide, and in Australia, dementia is the second leading cause of death, with an estimated 250 people diagnosed each day.
A stroke, meanwhile, is where the blood supply to the brain is disrupted, resulting in oxygen starvation, brain damage and loss of function.
Globally, one in four adults over the age of 25 will have a stroke in their lifetime. Data suggests that 13.7 million people will have a stroke this year with 5.5 million dying as a result.
‘This research provides vital insights about heavy coffee consumption and brain health, but as with many things in life, moderation is the key,’ said Professor Hyppönen.
‘Together with other genetic evidence and a randomised controlled trial, these data strongly suggest that high coffee consumption can adversely affect brain health.
‘While the exact mechanisms are not known, one simple thing we can do is to keep hydrated and remember to drink a bit of water alongside that cup of coffee.’
Earlier this year, Swiss researchers found regular caffeine intake reduces the volume of grey matter in the brain, suggesting coffee intake could impair our information processing ability.
The experts gave volunteers three 150mg servings of caffeine a day for 10 days – a caffeine intake equating to about four or five small cups of brewed coffee a day, or seven single espressos.
They found a reduction in grey matter, which is mostly found on the outer-most layer of the brain, or cortex, and serves to process information.
UniSA has been consistently investigating the effects of coffee – one of Australia’s favourite beverages – on human health.
In February, the team revealed that long-term, heavy coffee consumption – six or more cups a day – can increase the amount of fats in your blood, increasing the risk of cardiovascular disease (CVD).
‘There’s certainly a lot of scientific debate about the pros and cons of coffee,’ said Professor Hyppönen at the time.
‘But while it may seem like we’re going over old ground, it’s essential to fully understand how one of the world’s most widely consumed drinks can impact our health.’
Professor Hyppönen and her colleague Ang Zhou looked at genetic and phenotypic associations between coffee intake and plasma lipid profiles – the cholesterols and fats in blood.
The study, published in Clinical Nutrition, used data from 362,571 UK Biobank participants, aged between 37 and 73 years.
Not only did they find a link between the two, but causal evidence that habitual coffee consumption contributes to an adverse lipid (fat) profile.
Coffee beans contain a very potent cholesterol-elevating compound called cafestol, which mainly present in unfiltered brews, such as French press, Turkish and Greek coffees, but also in espressos.
Espressos are the base for most barista-made coffees, including lattes and cappuccinos. If you order a coffee on the high street, you’re likely to be served an espresso, whether it’s with or without milk.