Scientists Discover Viable Biomarker of Coffee Consumption

Millions of people around the world drink coffee every day. This beverage contains a gigantic number of bioactive substances, and its effects on human health and metabolism are often the subject of scientific studies. However, in many of these studies, data on coffee consumption are largely based on self-reports and are therefore not always right. This can affect the scientific validity of nutritional studies.

A research team led by the Leibniz Institute for Food Systems Biology at the Technical University of Munich has confirmed the usefulness of a specific compound found in roasted coffee and proposed it as a up-to-date, practical food biomarker. Tests is published in the journal Drinks.

Biomarkers could be the cure

Reliable biomarkers could solve this problem by using biological samples to objectively distinguish between coffee drinkers and non-drinkers. “However, so far only a few substances are known that could be used as markers for coffee,” says lead researcher Roman Lang from the Leibniz Institute. “However, they have not yet been sufficiently tested or available in sufficient quantities to serve as reference substances for comparative measurements in nutritional studies,” he continues.

The research team, which also includes dietitian Thomas Skurk and first author Beate Brandl from ZIEL—Institut for Food & Health at the Technical University of Munich, comprehensively evaluated the roasted coffee compound N-methylpyridinium as one of the biomarker candidates for its usefulness. Scientists from the Technical University of Munich first proposed this substance as a biomarker candidate in 2011 as part of a pilot study.

Data from over 460 people were analyzed

As part of the scientific validation, the team analyzed existing data from the literature. They also analyzed urine, blood and plasma samples from more than 460 people from Freising and Nuremberg who participated in the nutritional study conducted by enable-Cluster.

As studies show, N-methylpyridinium is a compound specific to roasted Arabica and Robusta coffee. The substance is chemically very stable, and its absorption into the body depends on the concentration. The substance can also be easily and reproducibly detected in various body fluids after coffee consumption, before leaving the body unchanged in urine within hours to days.

Roman Lang, who heads the Biosystems Chemistry & Human Metabolism research group at the Leibniz Institute, explains: “As we have shown, N-methylpyridine meets all the criteria that science requires of a biomarker that monitors food intake. Even if we cannot draw direct conclusions about the amount of coffee consumed due to various factors, the smoking substance is still suitable as a marker.

“This allows us to objectively and practically distinguish between people who drank coffee and those who didn’t. That’s why we propose it as a reliable qualitative biomarker of coffee consumption.”

N-methylpyridine was first proposed as a candidate biomarker of coffee consumption in 2011.

N-methylpyridine is formed from the natural alkaloid trigonelline, which is bountiful in green coffee, when exposed to high temperatures above 220°C. Depending on the degree of roasting, roasted Arabica and Robusta coffee beans contain concentrations of about 0.5 to 2 mg/g of the substance – regardless of special processing methods such as steaming or decaffeination. N-methylpyridine is present in brewed coffee (20–40 mg/l) and can be easily detected in blood, plasma and urine samples.

In the US alone, 74% of the population over 20 years of age describe themselves as coffee drinkers. In European countries, the calculated consumption of roasted coffee per person in 2022 ranged from about 4 kilograms in Italy to 10 kilograms in Luxembourg.