Two weeks without coffee: a 2026 study found changes in gut microbiota but did not prove a benefit

A study published in 2026 in the journal Nature Communications analysed how regular coffee consumption is linked to gut microbiota and what happens when people who drink it every day stop for 14 days. The paper's conclusion: coffee leaves a noticeable "trace" in the gut ecosystem, and part of that trace begins to change when the drink is absent from the diet.

The researchers first compared 31 regular coffee drinkers with 31 people who did not drink it. The first group was then asked to cut out coffee completely for two weeks.

Before quitting, the gut flora profile of coffee drinkers differed from that of non-drinkers: they had more bacteria of the genera Cryptobacterium and Eggerthella. Over 14 days without coffee, the levels of caffeine, theophylline and 1.7-dimethylxanthine in stool dropped noticeably, the amount of hippuric acid decreased and the amount of indole-3-carboxaldehyde rose.

After the break, participants began drinking coffee again for 21 days: some with caffeine, others without. The researchers recorded rapid changes in the microbiome after resumption, and some of them occurred regardless of whether the drink contained caffeine.

During abstinence, some measures of attention and alertness improved among the regular drinkers. After they resumed drinking coffee, perceived stress and some symptoms of depression decreased.

The 2026 study describes differences and changes, but it does not claim that the gut profile of people who do not drink coffee is healthier than that of those who do, or that two weeks of abstinence brings a specific clinical benefit. Nature Communications has been published since 2010.