It is widely believed that consuming coffee can be dehydrating because coffee has diuretic properties, increasing the risk of kidney stones. However, studies suggest the opposite.
Kidney stones are an increasingly common problem. Current estimates suggest that the prevalence is up to 15% of the general population. Each year, more than 500,000 people come to the emergency room with kidney stone problems.
Kidney stones form as a hard object due to chemicals in urine. Once formed, the stone can remain in the kidney or enter the urethra via the urinary tract. Stones that don’t move can lead to urine retention, which causes pain.
Some studies have consistently found an inverse relationship between coffee consumption and the occurrence of kidney stones.
In one study, researchers used the Mendelian randomization technique to determine the possible causal relationship between coffee consumption and the development of kidney stones.
Data from 571,657 participants with kidney stones from two studies were used, including 176,613 participants in the FinnGen study and 395,044 participants in the UK Biobank study.
The study examined how genetics influence the connection between coffee and kidney stones. The study design used genetic variants that are associated with higher coffee consumption. The results showed that increasing from 1 cup per day to 1.5 cups per day reduced the risk of kidney stones by 40%.
Available data were used and 12 single nucleotide polymorphisms (SNPs) were selected from genome-wide association studies that were associated with coffee consumption. Coffee consumption was assessed using food frequency questionnaires.
Causal estimates of coffee consumption were calculated using the inverse variance weighting method: a 40% reduction in the likelihood of stones was found for a 50% increase in consumption, corresponding to an increase of 1 to 1.5 cups per day.
The study data, along with observational data, should refute the misconception that coffee is dehydrating and a drink that people at high risk of kidney stones should avoid. This study provides causal evidence that the risk of kidney stones is reduced by coffee consumption.
Researchers offer several theories as to why coffee may help reduce the occurrence of kidney stones. They explain that urine flow is increased by caffeine intake, which is an important protective factor against the formation of kidney stones. It is important to mention that this caffeine consumption should be accompanied by adequate water intake.
The adhesion of calcium oxalate crystals to kidney cells can also be reduced by caffeine, and the coffee plant is rich in citric acid, and citrate in urine inhibits the formation of kidney stones.
