Salivary concentration of N-acylethanolamines upon food mastication and after meal consumption: Influence of food dietary fiber

The primary objective of this study was to evaluate the impact of the amount and type of food dietary fiber on salivary concentrations of N-acylethanolamines (NAEs) and glucose upon food mastication and in the post-prandial phase. Three types of biscuits enriched with 3% barley β-glucan (βGB) or whole-wheat bran (WWBB) or without dietary fiber (control, CB) were developed. A crossover randomized human study was carried out by collecting saliva samples from eighteen healthy and fasting participants in a resting condition, upon mastication of parafilm and one of the three biscuits. Subsequently, the amount of biscuits consumed in an ad-libitum breakfast was measured and post-prandial saliva samples, blood glucose, appetite, and food liking were collected over the following 2 h. Salivary concentration of oleoylethanolamide (OEA) and linoleoylethanolamide (LEA) significantly increased during all biscuits mastication compared to food-free conditions, with OEA increasing more (~ 138 folds) than LEA (~ 7 folds). Subjects consumed always 75 g of biscuits at breakfast. Salivary OEA peaked at 15 min and returned to baseline concentration at 60 min after consumption of all types of biscuits whereas LEA peaked only after WWBB. Fifteen minutes after βGB consumption all NAE levels were significantly lower than those after WWBB. No difference of biscuit type on post prandial blood glucose was recorded. Results demonstrated that NAEs were released in saliva during biscuit mastication, independently from dietary fiber composition. The type of dietary fiber could influence the persistence of NAEs in saliva over 30 min after consumption. Future studies will clarify the mechanisms behind these findings and the role of salivary NAEs in food liking and appetite cues after food consumption.