Drinking More Coffee May Reduce Acute Kidney Injury Risk

Drinking two to three cups of coffee a day significantly reduces the risk of acute kidney injury, a prospective cohort study suggests.

Participants who drank any quantity of coffee every day had an 11% lower risk of acute kidney injury than those who never drank coffee, report Kalie L. Tommerdahl, MD, of the University of Colorado Anschutz Medical Campus in Aurora, and colleagues, but the largest reductions were seen in the group that drank two to three cups a day.

The findings were published online May 5 in the journal Kidney International Reports.

"Our data support chronic coffee consumption as an opportunity for cardiorenal protection through diet, particularly for the prevention of acute kidney injury hospitalizations or procedures," the researchers write.

More Coffee, Decreased Risk

Researchers assessed 14,207 adults from the Atherosclerosis Risk in Communities (ARIC) study. Among the participants, 17% drank > 3 cups daily, 23% drank 2-3 cups daily, 19% drank 1 cup daily, 14% drank < 1 cup daily, and 27% never drank coffee. Mean age was about 54 years for the cohort.

During a single medical visit, participants completed food frequency surveys about coffee consumption as defined by the number of cups per day. The study team then compared incident acute kidney injury as determined by hospitalization with an acute kidney injury International Classification Diseases code.

During a median follow-up of 24 years, there were 1694 acute kidney injury incidents.

Coffee intake was greater in White participants, individuals without diabetes, smokers, men, and individuals with normal blood pressure, greater total energy intake each day, and lean body mass index (BMI).

The results also showed that greater coffee drinking was linked with reduced acute kidney injury risks compared with those who never consume coffee, as indicated by the following data:

Reference: never, P = .003
> 3 cups daily: hazard ratio (HR), 0.83 (95% CI, 0.71 - 0.96)
2-3 cups daily: HR, 0.83 (95% CI, 0.72 - 0.95)
1 cup daily: HR, 1.08 (95% CI, 0.94 - 1.24)
< 1 cup daily: HR, 0.92 (95% CI, 0.79 - 1.08)

Coffee consumption groups, patterns of acute kidney injury risk remained significant after multivariable adjustment for sex, age, education, total daily energy intake, race-center, alcohol intake, diet quality, smoking, systolic blood pressure, physical activity, BMI, estimated glomerular filtration rate, diabetes status, and antihypertensive prescription use.

No Need to Modify Caffeine Consumption

Acute kidney injury was an unlikely outcome in this study, and so advising people to modify their level of coffee consumption is not necessary, noted Joel Topf, MD, assistant clinical professor at Oakland University William Beaumont School of Medicine in Rochester Hills, Michigan. This study contributes to the body of literature showing the benefits of caffeine, he said. "Coffee is often demonized, and this is a nice little piece of data saying that a lot of the consensus of what we think about coffee really is not well deserved," Topf added.

Topf pointed out that the researchers only collected data on coffee consumption once in a 24-year study period, but that there may have been changes in participants' coffee consumption habits over that time.

Other study limitations include that the participants answered food frequency surveys based on memory instead of direct reporting to determine their average coffee consumption each day, the need to consider the consumption of other caffeinated drinks like soda and tea as it relates to potential confounding, and dependence on the inclusion of acute kidney injury based on the inpatient hospitalization codes, the researchers note.

Additional limitations include potential residual confounding given imprecise measurements and varying amounts of caffeine for each type of coffee and the different brew-associated factors, they add.

"Larger studies evaluating the effects of coffee consumption on kidney perfusion and oxygenation in individuals with impaired kidney function at high risk for acute kidney injury, as well as the effects of coffee on anti-inflammatory and antioxidant outcomes, are necessary to fully explain its potential cardiorenal protective effects," the researchers conclude.

Tommerdahl and Topf have reported no relevant financial relationships.

Kidney Int Rep. Published online May 5, 2022. Full text

Ashley Lyles is an award-winning medical journalist. She is a graduate of New York University's Science, Health, and Environmental Reporting Program. Previously, she studied professional writing at Michigan State University. Her work has taken her to Honduras, Cambodia, France, and Ghana and has appeared in outlets such as The New York Times Daily 360, PBS NewsHour, The Huffington Post, Undark, The Root, Psychology Today, Insider, and Tonic (Health by Vice), among other publications.

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