Drinking 6 or more cups of coffee daily reduces risk of gallstone disease

Denmark: Daily intake of 6 or more cups of coffee may provide protection against the development of gallstones, a recent study involving more than 100,000 adults across 13 years has claimed. The study is published in the Journal of Internal Medicine.

According to the study, those who drank more than six cups of coffee daily were at 23% lower risk of developing symptomatic gallstones than those who did not drink coffee. Also, drinking one extra coffee cup was associated with a 3% lower risk.

Gallstones are solid particles formed from bile cholesterol and bilirubin -- an orange-yellow pigment that occurs normally when part of your red blood cells break down. The gallstones are formed when there is too much cholesterol and not enough of the bile acids that prevent them from becoming stones.

"Caffeine is released via bile and contains chemical compounds called methylxanthines that stimulate the production of acid and prevent the cholesterol from forming gallstone," wrote the authors.

A. T. Nordestgaard, Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark, and colleagues tested whether high coffee intake causally protects against symptomatic gall stone disease (GSD) using a Mendelian randomization design.

Firstly, the researchers tested whether coffee intake lowered GSD risk in 104 493 individuals from the general population. Mean follow‐up was 8 years (range: <1–13 years). Secondly, they tested whether the genetic variants (near CYP1A1/A2 [rs2472297] and AHR [rs4410790]), combined as an allele score, were associated with higher intake of coffee. Thirdly, they tested whether the allele score was associated with a lower risk of GSD in 114 220 individuals including 7294 gallstone events. Mean follow‐up was 38 years (range: <1–40 years).

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Key findings include:

• In the observational analysis, those with a coffee intake of >6 cups daily had a 23% lower risk of GSD compared to individuals without coffee intake.


• In genetic analysis, there was a stepwise higher coffee intake of up to 41% (caffeine per day) in individuals with 4 (highest) versus 0 (lowest) coffee intake alleles and a corresponding stepwise lower risk of GSD up to 19%.


• The estimated observational odds ratio for GSD for a one cup per day higher coffee intake was 0.97 (0.96–0.98), equal to 3% lower risk. The corresponding genetic odds ratio was 0.89, equal to 11% lower risk.

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The figure below sums up the study:

Source: Journal of Internal Medicine

Although the study only uncovered correlations, the authors highlighted several mechanisms by which coffee consumption might help prevent gallstones from forming.

"A coffee-induced increase in bile acid production could reduce the risk of cholesterol gallstones," wrote the authors.

"Moreover, coffee has been shown to induce UGT1A1, the enzyme responsible for the conjugation of bilirubin. Elevated levels of unconjugated bilirubin in bile is a causal risk factor for gallstone formation."

To read the complete study log on to https://doi.org/10.1111/joim.12970