A new genetic analysis has uncovered a potential biological pathway explaining how drinking filtered coffee may help lower blood sugar. Research from Peking University, published in npj Science of Food, used a large-scale study to connect filtered coffee consumption, specific gut bacteria, and lower average blood glucose levels, offering a new piece in the puzzle of coffee's health effects.
The study employed Mendelian randomization, a method that uses genetic variation to assess causal relationships, on data from over 500,000 individuals in the UK Biobank. Researchers examined the link between six different coffee consumption patterns and HbA1c, a key marker for long-term blood glucose control. Of the types studied—including instant coffee with milk, sweetened coffee, and decaf—only filtered coffee was significantly associated with lower HbA1c levels.
To understand the mechanism, the team analyzed gut microbiome data. They found that the bacterium Veillonella, one of several known to produce glucose-regulating propionic acid, appears to mediate the effect. Filtered coffee consumption was linked to this specific bacterium, which in turn was associated with lower blood sugar. The authors suggest that the unique chemical profile of filtered coffee, which is lower in lipids but retains high levels of polyphenols, may be responsible for promoting this beneficial gut activity.