Effects of daily extra virgin olive oil consumption on biomarkers of inflammation and oxidative stress: a systematic review and meta-analysis.

Extra virgin olive oil (EVOO) has recognized antioxidant and anti-inflammatory properties, mainly because its composition, great levels of oleic acid, and phenolic compounds (PC). Thus, the aim of this systematic review was to synthesize the results of randomized controlled clinical trials (RCTs) of regular consumption of EVOO in biomarkers of inflammation and oxidative stress. Twenty-three RCTs met the inclusion criteria, involving 1138 participants, showed some type of risk of bias and the certainty of the evidence ranged from moderate to very low. Biomarkersas such ox-LDL, TNF-alpha, CRP, IL-6, IL-10, and IL-18 were associated with changes in inflammatory and oxidative states after EVOO consumption. EVOO consumption reduced ox-LDL when compared with medium and low PC olive oils together: -4.59 U/l [(95%CI: -8.1 to -1.08), I²: 45.4%; p = 0.103] and with low PC olive oil only: -7.73 U/l [(95%CI: -14.63 to -0.82 U/l], I²: 42%; p = 0.16)]. CRP was also reduced compared to low PC olive oils: -0.99 mg/l [(95%CI: -1.66 to -0.31); I²: 68.8%; p = 0.00)], but showed considerable heterogeneity. In conclusion, PC levels demonstrate an association with anti-inflammatory and antioxidant effects. The consumption of EVOO tends to reduce the risk of chronic non-communicable diseases, especially individuals adhering to the Mediterranean diet.