Association between coffee consumption and metabolic syndrome: A cross-sectional and Mendelian randomization study

This study investigates the associations between coffee consumption and metabolic syndrome and its components, as well as the effect of milk, sugar, and artificial sweeteners on these associations.

A cross-sectional analysis was conducted with 351805 UK Biobank participants. Coffee consumption data were collected via food frequency questionnaires and 24-h recall. Metabolic syndrome was identified through blood biochemistry and self-reported medication use. Odds ratios were calculated using multivariable logistic regression, and results were verified with two-sample Mendelian randomization.

Consuming up to two cups of coffee per day was inversely associated with metabolic syndrome (1 cup/day: odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.85-0.92; 2 cups/day: OR: 0.90, 95% CI: 0.86-0.93). Higher intakes showed near-null associations. Mendelian randomization did not support a causal link between coffee intake and metabolic syndrome. Both self-reported and genetically predicted high coffee consumption (four cups per day or more) were associated with central obesity. The inverse association between coffee consumption and metabolic syndrome was more profound among drinkers of ground coffee than those of instant coffee. Results were similar when stratified by the use of milk and sugar, yet the use of artificial sweetener with coffee was positively associated with metabolic syndrome and all component conditions.

Coffee consumption may increase the risk of central obesity but is unlikely to impact the risk of metabolic syndrome. The potential health effects of artificial sweeteners in coffee need further investigation.