Abstract
Background and Aims
Chronic degenerative non-communicable diseases represent one of the main causes of death in the world. Among these, chronic kidney disease (CKD) has an estimated prevalence of 7-12% worldwide. CKD is related to numerous comorbidities, especially these cardiovascular. Furthermore, its progression is characterized by a low-grade inflammatory status and oxidative stress, factors that negatively influence quality of life. In recent years, numerous in vitro and in vivo studies have analysed the beneficial effects of natural bioactive compounds on health. Extra virgin olive oil (EVOO) is rich in minor polar compounds (MPCs), capable of exerting a cardioprotective, anti-inflammatory and antioxidant action. The 98-99% of EVOO total weight is made up by fatty acids, in particular, monounsaturated ones such as oleic acid, and a small percentage 1-2% by MPCs. Among MPCs, hydroxytyrosol, tyrosol, oleacin and oleocanthal are of particular importance for their heathy effects. In our study, we analysed the potential healthy effects of EVOO MPCs in CKD patients.
Method
The EVOO selected for the study (Ophenoil), was previously characterized for its high content of MPCs through quantitative and qualitative analysis performed using HPLC-DAD-MS and Oxitester. We enrolled 20 CKD patients undergoing conservative therapy (stages I-IV according to K-DIGO guidelines). All enrolled patients have been instructed to assume 40 ml per day of EVOO, for 9 weeks. Laboratory parameters have been collected at two different time-points of the study (at baseline T0 and after 9 weeks T1) (Fig 1). At T0 the patients have been undergo to a detailed medical history. All CKD patients have been unstructured to follow a conventional Mediterranean diet (which adherence is assessed by PREDIMED questionnaire), containing a controlled protein intake according to CKD stage, in which the EVOO Ophenoil represent the main source of plant-based fats. In both time-points of the study, all patients have been undergoing to blood sampling to evaluate renal function, lipid profile, inflammatory parameters (C-reactive protein-CRP, erythrocyte sedimentation rate-ESR, Interleukin(IL)-6, Tumor necrosis factor(TNF)-α) and oxidative stress (Free Oxygen Radicals Test-FORT and Free Oxygen Radical Defence-FORD by CR4000). Moreover, we evaluated the cardiovascular risk indices (Carotid intima-Media Thickness (C-ITM) monitored by eco(color)Doppler ultrasound). Each patient has been interviewed with Quality of Life Assessment Questionnaire (Short-Form 36 items health Survey- SF-36) and International Physical Activity Questionnaire (IPAQ).
Results
Preliminary data highlight a reduction of the inflammatory state, monitored by CRP (p=0.0299), ESR (p=0.0063), TNF-α (p=0.0001), IL-6 (p=0.0219), an improvement of renal function (azotemia, p=0.0256) and of lipid profile (triglycerides, p=0.0476) after 9 weeks of EVOO assumption (Fig 2). Moreover, we observed a significant improvement of the C-ITM (p=0.0146) and a significant reduction of oxidative stress monitored by FORT (p=0.0144). The results of the PREDIMED and IPAQ questionnaires showed no significant differences. This data indicates that patients have not changed their lifestyle and the results obtained are attributable to EVOO assumption. At the end of the study, there was an improvement of quality of life, in the domains of emotional well-being (p=0.0340) and general health (p=0.0405) of SF-36 questionnaire (Fig 3).
Conclusion
The consumption of EVOO with high MPCs content would seem to exert an anti-inflammatory (due to high content of oleocanthal) and antioxidant (due to high content of hydroxytyrosol, oleacin and oleuropein aglicone) action in CKD patients. Therefore, once again it is highlighted how the diet therapy plays a pivotal role in the clinical management of CKD patients and that it allows an improvement of their quality of life.
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