Performance of plasma trigonelline as a marker of coffee consumption in an epidemiologic setting.

Background: Coffee is a widely consumed beverage, and studies suggest that drinking coffee has beneficial health effects. The phytohormone trigonelline is present in large amounts in coffee beans, and circulating concentrations of trigonelline have been shown to be positively related to dietary intake of coffee and to increase significantly after the consumption of a bolus dose of coffee. Objective: We cross-sectionally investigated the utility of plasma trigonelline as a marker of coffee consumption in an epidemiologic setting. We secondarily investigated if coffee intake is related to plasma concentrations of vitamin B-3 (niacin) forms. Design: In a Norwegian cohort of 3503 participants, we combined questionnaire data on the number of cups of coffee consumed per day with plasma trigonelline to evaluate trigonelline as a marker of coffee intake. The suitability of plasma trigonelline to discriminate those not consuming from those consuming coffee was investigated by receiver operating characteristic (ROC) analysis. Plasma collected at 2 time points 1 y apart was used to determine the within-person reproducibility of trigonelline.
Results: We found that plasma trigonelline concentrations increased strongly with increasing amounts of coffee consumed. ROC analysis showed that trigonelline had an area under the curve of 0.92 (95% CI: 0.90, 0.94) for distinguishing coffee abstainers from coffee drinkers. Plasma trigonelline had a good within-person reproducibility (0.66; 95% CI: 0.64, 0.68) for samples collected 1 y apart. The amount of coffee consumed was not associated with plasma concentrations of the niacin vitamers nicotinamide and N1-methylnicotinamide. Conclusions: Plasma trigonelline performs well as a marker of coffee intake. Data used in this study were derived from the clinical trial registered at www.clinicaltrials.gov as NCT00354081.