Oral Fat Sensitivity in Humans: Links to Saliva Composition Before and After Stimulation by Oleic Acid

Fat perception is a complex sensation dependent on different sensory cues, such as texture and olfaction, and also potentially taste. In addition, saliva can interact with dietary fat during its consumption and influence the perception of fatty acids. Because previous studies had identified subjects who were hyper- and hyposensitive to the perception of free fatty acids, the first aim of this work was to study whether saliva composition is different in groups of subjects having low and high oral sensitivity to a free fatty acid, oleic acid (C18:1). The second aim was to determine whether oral stimulation with C18:1 could modify the composition of saliva. To verify these hypotheses, two groups of individuals were selected from a panel of 73 subjects: one group sensitive + to C18:1 (n = 12) and one sensitive - to C18:1 (n = 13). Overall, no differences were found in the saliva characteristics between the two groups. However, significant differences after C18:1 stimulation when comparing to a control stimulation were observed in the sensitive + group: in this group, the increase in antioxidant capacity and the decrease in lipolytic activity were significant, while it was not in the sensitive - group although the median values were similar for this last variable in the two groups. This would suggest that the response given by the salivary system to fatty acid stimulation is different in groups of subjects having low and high oral sensitivity to C18:1.