nutrients Article Relationship between Mediterranean Diet Adherence and Saliva Composition Teresa Louro 1 , Carla Simões 1 , Maria João Penetra 2 , Laura Carreira 1 , Paula Midori Castelo 3 , Henrique Luis 4,5 , Pedro Moreira 6 and Elsa Lamy 1, *   Citation: Louro, T.; Simões, C.; Penetra, M.J.; Carreira, L.; Castelo, P.M.; Luis, H.; Moreira, P.; Lamy, E. Relationship between Mediterranean Diet Adherence and Saliva Composition. Nutrients 2021, 13, 1246. https://doi.org/10.3390/nu13041246 Academic Editor: Emilio Sacanella Received: 19 March 2021 Accepted: 8 April 2021 Published: 10 April 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 MED (Mediterranean Institute for Agriculture, Environment and Development), Institute for Advanced Studies and Research (IIFA) IIFA—Instituto de Investigação e Formação Avançada, University of Évora, 7002-556 Évora, Portugal; teresalouro@hotmail.com (T.L.); carlasimoes3@hotmail.com (C.S.); d47128@alunos.uevora.pt (L.C.) 2 Department of Biology, University of Évora, 7002-556 Évora, Portugal; l37950@alunos.uevora.pt 3 Department of Pharmaceutical Sciences, Universidade Federal de São Paulo (UNIFESP), Diadema 09972-270, Brazil; pcastelo@yahoo.com 4 Unidade de Investigação em Ciências Orais e Biomédicas (UICOB), Faculdade de Medicina Dentária, Universidade de Lisboa, 1600-277 Lisboa, Portugal; henrique.luis@fmd.ulisboa.pt 5 Center for Innovative Care and Health Technology (ciThecCare), Politécnico de Leiria, 2411-901 Leiria, Portugal 6 Faculdade de Ciências da Nutrição e Alimentação da Universidade do Porto, 4150-180 Porto, Portugal; pedromoreira@fcna.up.pt * Correspondence: ecsl@uevora.pt; Tel.: +351-266-760-885 Abstract: Dietary polyphenol exposure is known to change protein saliva composition in rodents, but less is known in humans. The present study aimed to assess the relationship between saliva protein composition and adherence to Mediterranean Diet (MD) and polyphenol intake levels. Participants were assessed for their dietary habits, which were converted in Mediterranean adherence level, according to Mediterranean Diet Adherence Score (MEDAS) score. Total polyphenol and total flavanol intakes were extrapolated from dietary data, using Phenol explorer database. Whole saliva was collected, and proteins were separated by SDS-PAGE. Salivary S-type cystatins were highly expressed in the group with medium adherence to MD, being positively correlated with wine intake in overweight individuals. The association between salivary amylase and MD adherence also depended on Body Mass Index (BMI), with a positive association only in normal weight individuals. Polyphenol intake was positively associated with S-type cystatins levels, particularly when flavanols were considered separately. These results show that saliva relationship with MD adherence depend on BMI, suggesting that normal weight and overweight individuals may have different salivary responses to diet. Moreover, these results reinforce the link between saliva and dietary polyphenols (flavanols) levels, leading to the hypothesis that salivary proteome can have a role in polyphenol-rich foods acceptance. Keywords: dietary polyphenols; Mediterranean diet; salivary amylase; salivary cystatins 1. Introduction Mediterranean Diet (MD) is accepted as one of the most healthy and sustainable dietary patterns. High adherence to MD has been shown to relate with several different health benefits, such as obesity reduction, diabetes, and cardiovascular protection, among many others [1,2]. Despite of these advantages, only a minimal percentage of the population has high adherence to MD, even in Mediterranean countries [3–5]. In a recent study made for the Portuguese population, participants reported different reasons to justify the medium-low adherence levels, among which is food’s flavor [6]. The MD dietary pattern is characterized by the intake of considerable amounts of vegetables, fresh fruits, and whole grain cereals, with moderate to low amounts of products Nutrients 2021, 13, 1246. https://doi.org/10.3390/nu13041246 https://www.mdpi.com/journal/nutrients