Coffee and Cake Together: Seoul Study Finds Caffeine, Not Sugar, Drives Risk in Kids

A latte and a slice of cake seem like a harmless indulgence, but for children and teenagers the combination can quietly push caffeine intake past recommended limits. That is the central finding of a new analysis of café products in Seoul, where researchers measured caffeine and sugars in nearly one hundred beverages and desserts and then asked a deceptively simple question: how often does a single beverage–dessert pairing exceed dietary reference values?

The study, conducted by scientists at the Seoul Metropolitan Government Research Institute of Public Health and Environment and published in Food Science and Biotechnology, analyzed 99 café products using high-performance liquid chromatography, a gold-standard analytical technique that separates and quantifies individual compounds in complex mixtures. The results reveal a striking division of labor between the two halves of the classic café pairing. Beverages delivered the bulk of the caffeine, averaging 88.02 milligrams per serving with a large standard deviation of 62.77 milligrams, while desserts contributed most of the added sugars, averaging 20.41 grams per serving compared with just 7.21 grams in beverages.

That asymmetry matters because the two nutrients carry very different risk profiles across age groups. Caffeine is a central nervous system stimulant whose safe intake levels are defined per kilogram of body weight, meaning children and adolescents face far lower absolute thresholds than adults. Added sugars, by contrast, are judged against recommendations expressed as a percentage of total energy intake, a criterion that the study found far fewer pairings violated.

To translate laboratory measurements into real-world risk, the team employed two complementary assessment frameworks. The first was a deterministic approach, which simply adds the measured caffeine and sugar contents of each beverage–dessert combination and compares the totals against dietary reference values. Across the age groups spanning young children aged 9 to 11 through adolescents aged 15 to 18, between 28 and 43 of the 90 possible pairings—roughly 31 to 48 percent—exceeded the caffeine reference value under this straightforward calculation. Only 4 pairings, or 4.4 percent, exceeded the added sugars threshold.

Deterministic assessment, however, treats every serving as identical, ignoring the natural variability in how products are prepared and consumed. To capture that uncertainty, the researchers turned to Monte Carlo simulation, a probabilistic technique widely used in dietary exposure assessment. Rather than assuming fixed values, the method repeatedly samples from the measured distributions of caffeine and sugar content, generating thousands of hypothetical pairing scenarios and calculating how often each one crosses the threshold. The approach, guided by methodology frameworks from the European Food Safety Authority, produces an exceedance probability for every pairing rather than a simple yes-or-no verdict.

The probabilistic results were sobering. Between 17 and 40 pairings—18.9 to 44.4 percent depending on age group—showed a greater than 50 percent probability of exceeding the caffeine dietary reference value. For added sugars, only 3 pairings, or 3.3 percent, crossed their threshold with that level of probability. The convergence of both methods on the same conclusion strengthens the finding: caffeine, not sugar, is the dominant driver of exceedance risk when café beverages are paired with desserts, particularly for younger consumers.

The analytical rigor underpinning these conclusions followed internationally harmonized guidelines. Method validation adhered to standards from the International Council for Harmonisation and the Association of Official Analytical Collaboration, with detection and quantification limits established for both analytes. Statistical comparisons of product categories relied on non-parametric tests appropriate for the skewed distributions typical of food composition data, and normality was formally assessed before parametric procedures were applied.

Why should caffeine thresholds be so easy to breach? The answer lies in developmental physiology. Children and adolescents have lower body masses and, according to toxicological reviews, may exhibit differential sensitivity to stimulant compounds compared with adults. Health authorities including the European Food Safety Authority have established age-graduated caffeine limits precisely because the margin between a typical serving and a problematic dose narrows considerably with decreasing body weight. A single large coffee-based beverage can approach or exceed a child’s entire daily allowance before any dessert is factored in, and the pairing structure of café menus makes combined consumption the norm rather than the exception.

The sugar findings, while less alarming on their own, add context to ongoing public health debates. The World Health Organization recommends limiting free sugars to less than 10 percent of total energy intake, and national surveys in South Korea have documented rising sugar consumption driven substantially by beverages and processed foods. The fact that most pairings stayed within sugar limits suggests that dessert portions in Seoul cafés, while sweet, are calibrated to adult energy budgets. The concern is cumulative: a child consuming a sugary café drink plus a dessert may derive a substantial fraction of daily energy from added sugars even when no single pairing formally exceeds the threshold.

For regulators and public health officials, the study’s dual-method framework offers a practical template. Deterministic screening quickly flags the worst offenders, while Monte Carlo simulation quantifies how confident one can be that a given pairing poses genuine risk, accounting for serving variability and analytical uncertainty. Applied to Seoul’s café market, the combined approach identified a substantial subset of popular combinations—particularly those built around high-caffeine beverages—that warrant attention when marketed to or consumed by younger customers. As café culture continues its global expansion, the message for parents is straightforward: the caffeine in the cup, not the sugar on the plate, is what most deserves scrutiny when children order dessert alongside a drink.

Subject of Research: Caffeine and added sugar content of café beverage–dessert pairings and their dietary exceedance risk in children and adolescents

Article Title: Caffeine and sugars in café beverage–dessert pairings in Seoul: deterministic and probabilistic exceedance assessment

Article References: Caffeine and sugars in café beverage–dessert pairings in Seoul: deterministic and probabilistic exceedance assessment. (n.d.). https://doi.org/10.1007/s10068-026-02312-8

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02312-8

Keywords: caffeine, added sugars, café beverages, desserts, dietary reference values, Monte Carlo simulation, HPLC, food analysis, children's health, Seoul, dietary exposure, public health