Avid coffee drinkers are at higher risk of developing kidney disease, a new study has warned.
Scientists from Johns Hopkins Bloomberg School of Public Health found metabolites in the blood related to coffee consumption have the potential to raise the risk of developing the dangerous condition.
The researchers examined 372 blood metabolites – which refer to small molecules that are intermediates and products of metabolism – in almost 5,000 people in the study.
They found one metabolite associated with coffee that could help the kidneys become healthier, but two other coffee-related metabolites were found to be linked to a higher risk of kidney disease.
The latter metabolites are also associated with smoking, said the scientists, whose findings were published in the Clinical Journal of the American Society of Nephrology.
Chronic kidney disease is a long-term condition that is commonly associated with getting older and can worsen over time, according to the NHS. The condition can be caused by high blood pressure, diabetes, high cholesterol, kidney infections, and other conditions that put a strain on the kidneys.
According to the charity Kidney Care UK, around three million people in the UK have kidney disease. Black, Asian and minority ethnic communities are five times more likely to develop chronic kidney disease compared to other groups, it adds.
Previous studies have suggested that drinking coffee could be beneficial for kidney function. A recent study, published in May 2020, found that drinking an extra cup of coffee per day “conferred a protective effect” against chronic kidney disease.
But researchers at the Johns Hopkins School said the identification of the two metabolites that could lead to a higher risk of kidney disease were “surprising”.
Dr Casey Rebholz, associate professor of epidemiology at the Johns Hopkins School, said: “A large body of scientific evidence has suggested that consuming a large amount of coffee is consistent with a healthy diet.
“We were able to identify one metabolite that supports this theory.
“There were two other metabolites associated with coffee that surprisingly were associated with a higher risk of incident chronic kidney disease.
“These compounds were also associated with cigarette smoking, which may in part explain why these compounds were associated with a higher risk of kidney disease.”
The researchers did not account for people’s self-reported coffee consumption and said further study was needed.
Fiona Loud, policy director at Kidney Care UK, told The Independent: “Over the last few years there have been a number of studies that have found a relationship between coffee consumption and kidney health, which have attracted lots of comments.
“However there are as many studies that show a protective effect as there are that show a link to a decline in kidney health. We know that many people love coffee but as with most things in life, moderation and balance is the key when it comes to living healthily so we would urge people who do not have kidney disease to follow the current guidance which is to limit your maximum coffee consumption to no more than four cups a day.
“For those who have advanced or late stage Chronic Kidney Disease, as coffee contains potassium
so we would recommend that you are very careful about how much coffee you consume; please speak to your GP or kidney doctor so they can advise how much is right for you.”