Salivary evaluation of young habitual caffeine consumers: biochemical and taste characteristics

Abstract

Objective: Caffeine may be related to systemic effects, but information on sex differences and its influence on salivary characteristics is scarce. This study assessed the relationship between caffeine consumption, saliva and gustatory characteristics and heart rate in healthy adults. Material and Methods: The sample was composed of 60 individuals (30 men/30 women; 18-27y). Caffeine-based foods, beverages and medicines intake were assessed in three pre-set days. Gustatory sensitivity, resting heart rate, and salivary flow, pH, amylase (AMY), total protein (TP), and caffeine levels were evaluated in stimulated (SS) and unstimulated saliva (US). The data were analyzed using paired t-tests/Wilcoxon tests, one-way and two-way ANOVA, Spearman correlation, and hierarchical regression (α = 0.05). Results: The reported caffeine intake was higher in males and caffeine concentration was higher in SS compared to US (p=0.029). Salivary caffeine correlated with pH (rho=0.29; p=0.025), while SS AMY and TP concentrations were lower in caffeine consumers. No difference was observed in gustatory sensitivity and resting heart rate considering caffeine intake. According to the hierarchical regression model, caffeine salivary concentration was predicted by age, caffeinated food/beverages intake on the day of collection, and female sex (p=0.001; R2=0.25). Conclusion: Caffeine intake showed subtle effects on salivary pH and TP. However, a relationship between salivary caffeine concentrations and sex was evidenced, with women consuming less but showing higher salivary caffeine concentration, information useful when considering saliva as a source of caffeine biomarkers.

KEYWORDS

Caffeine; Heart rate; Saliva; Sex differences; Taste perception.