Evaluating sensory impacts of sustained Plant-Based Diets: Altered sensitivity and hedonic responses to Meat-Related odours in Sri Lankan young adults

The global surge in the adoption of plant-based diets (PBD) over the past decade, driven by an increasing awareness of its health and environmental advantages, underscores the need to investigate the relationship between PBD and sensory perception. In many Asian countries, vegetarianism is a traditional dietary regimen. The current cross-sectional study, involved Sri Lankan young adults, aims to test for potential differences in olfactory perception across individuals following vegetarian, flexitarian, or omnivore dietary pattern. A total of 153 participants (female = 84; age = 20–39 years) were tested for their supra-threshold sensitivity (d’) and hedonic responses to 3 plant-related (i.e., mushroom, cooked green leaves, soya) and 3 meat-related (i.e., chicken, steak, steamed-fish) odours. Based on self-reported category and Food Frequency Questionnaire, the participants were classified into vegetarian (n = 55), flexitarian (n = 26), and omnivore (n = 72) groups. Univariate analyses revealed that individuals following a PBD or flexitarian diet rated the testing meat-odours to be less pleasant, than omnivorous dieters (all p < 0.001). Furthermore, the vegetarian and flexitarian groups also showed higher sensitivities to the meat-odours than the omnivore group (all p = 0.002–0.028). No difference was detected across the three groups in terms of hedonic responses or sensitivity to the plant-related odours (all p > 0.1). Our findings revealed moderate and odour-specific differences in both olfactory sensitivity and hedonic responses between these dietary groups. These findings shed light on the potential key role of olfactory perception in sustaining a PBD regimen, suggesting that a gradual sensory adaptive process or training could be crucial for a successful dietary transition to PBD.