Olfactory and Gustatory Perception among Plant-Based vs. Omnivorous Dieters: A Systematic Review and Meta-Analysis

Abstract

Driven by heightened awareness of environmental sustainability, personal health, and animal welfare, there has been a rapid surge in adoption of plant-based diets (PBDs) by global consumers. Despite the important implications of potential links between PBDs and chemosensory (e.g., olfactory and gustatory) perception, the empirical evidence has yet to be comprehensively reviewed. This systematic review aims to synthesise existing data comparing olfactory and gustatory perceptions among individuals following plant-based (including vegan, vegetarian, and flexitarian) and omnivorous diets. Seven databases produced 1038 publications for screening against the pre-registered criteria. Eleven studies were included in this review, with three focusing on olfaction and eight on gustation. Of these, three gustatory studies provided sufficient data for meta-analysis, revealing little difference between plant-based and omnivore dieters on an overall level. The PBD group exhibited a significantly lower threshold (i.e., higher sensitivity) to sweetness compared to the omnivore group (ES = −0.336, 95% CI between −0.630 and −0.042, p < 0.05). Additionally, olfactory studies indicated that PBD followers perceived meat-related odours to be less pleasant compared to omnivores. Overall, this review points to a sensory–diet relationship, highlighting the potential role of sensory perception in sustainable plant-based dietary behaviours. The findings also encourage food manufacturers to consider potential chemosensory alterations among plant-based consumers.