The Mediating and Moderating Effects of Physical Fitness of the Relationship between Adherence to the Mediterranean Diet and Health-Related Quality of Life in University Students.

Noelia María Martín-Espinosa,Alberto González-García,Miriam Garrido-Miguel,Ana Isabel Cobo-Cuenca,Vicente Martínez-Vizcaíno,Andrés Redondo-Tébar

doi:10.3390/nu12113578

Abstract

The aim of this study was to estimate the relationship between the adherence to the Mediterranean diet (MD) and health-related quality of life (HRQoL) in university students and to assess whether this relationship is mediated or moderated by cardiorespiratory fitness (CRF) and handgrip strength. A cross-sectional study was performed involving 310 first-year Spanish university students. Adherence to the MD was evaluated with the 14-item Mediterranean Diet Adherence Screener (MEDAS), and the HRQoL was evaluated with the Short Form-12 (SF-12) questionnaire. CRF was assessed by the 20 m shuttle run test, and the handgrip strength was determined by dynamometry. ANCOVA models showed that participants with higher CRF and handgrip strength levels had significantly higher scores in the physical component summary (PCS) and mental component summary (MCS) of the SF-12 and in the MEDAS questionnaire than those with medium and low scores (p < 0.050). Additionally, the ANCOVA models showed that students with good adherence to the MD showed higher scores in the MCS of HRQoL than those with low adherence (p = 0.044, ES = 0.013), but these results did not appear for the PCS of HRQoL (p = 0.728, ES = 0.001). In the mediation analysis, it was found that CRF and handgrip strength acted as full mediators of the relationship between adherence to the MD and the MCS of HRQoL. In the moderation analysis, it was evidenced that CRF and handgrip strength did not act as moderators in the relationship between adherence to the MD and the MCS of HRQoL. In conclusion, adherence to the MD does not seem to have a direct effect on the MCS of HRQoL because this association seems to be fully mediated by CRF and handgrip strength.

Highlights

The interest in research of health-related quality of life (HRQoL) and its association with healthy lifestyles has grown in recent years; this subject has been less studied in young adults [1,2,3]
Numerous studies on the instruments that measure HRQoL have recognized the existence of two main summaries [10,11]: the physical component summary (PCS) and the mental component summary (MCS)
To the best of our knowledge, this is the first study to analyze the role of physical fitness in the relationship between adherence to the Mediterranean diet (MD) and the MCS of HRQoL in a sample of Spanish university students using a mediation and moderation analysis

Summary

Introduction

The interest in research of health-related quality of life (HRQoL) and its association with healthy lifestyles has grown in recent years; this subject has been less studied in young adults [1,2,3]Nutrients 2020, 12, 3578; doi:10.3390/nu12113578 www.mdpi.com/journal/nutrientsNutrients 2020, 12, 3578 than in other age groups [4,5,6,7,8]. The interest in research of health-related quality of life (HRQoL) and its association with healthy lifestyles has grown in recent years; this subject has been less studied in young adults [1,2,3]. Numerous studies on the instruments that measure HRQoL have recognized the existence of two main summaries [10,11]: the physical component summary (PCS) and the mental component summary (MCS). A positive association between the adherence to the MD and HRQoL in both healthy adults [6,7] and adolescents [13,14] has been reported. The components of physical fitness associated to health include cardiorespiratory fitness (CRF) and muscle strength. Research has demonstrated the impact of high levels of CRF and muscle strength on better health outcomes [18,19]

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