Mediterranean diet adherence modulates the plasma antioxidant response to long-term extra-virgin olive oil consumption in older adults

BACKGROUND AND AIMS: Phenolic compounds in extra-virgin olive oil (EVOO) may improve oxidative status, yet responses may vary across populations and dietary contexts. This study was aimed to evaluate whether long-term consumption of a tyrosol/hydroxytyrosol-enriched EVOO (HP-EVOO) improves plasma total antioxidant capacity (TEAC) in older adults at high cardiovascular risk, and whether baseline adherence to a Mediterranean diet (MedDiet) modifies this response. METHODS: In this pilot randomized intervention trial, 34 older adults (73.1 ± 5.9 years; 65% men) stratified as healthy controls or post-myocardial infarction (post-MI) consumed 25 mL/day of standard EVOO, HP-EVOO, or refined olive oil (ROO) for 26 weeks. Plasma TEAC was measured at baseline and follow-up. Baseline MedDiet adherence was derived from 3-day food diaries and categorized as low vs high. RESULTS: TEAC changes differed by clinical status within the EVOO group: post-MI participants showed a greater increase than healthy controls (+402 μM; 95% CI 162-641). Similarly, within the EVOO group, participants with high vs low MedDiet adherence exhibited a greater TEAC increase (+274 μM; 95% CI 1.6-545). No significant between-group TEAC differences were observed after HP-EVOO or ROO. CONCLUSION: In older adults, standard EVOO with moderate phenolic content improved plasma TEAC in post-MI participants and in those with higher baseline MedDiet adherence, whereas further phenolic enrichment did not enhance TEAC. These findings suggest that antioxidant responses to olive oil are context-dependent and not solely driven by phenolic concentration. Larger trials are warranted.