Research paper
Guasch-Ferre M, Hu FB, Martinez-Gonzalez MA, Fito M, Bullo M, Estruch R, Ros E, Corella D, Recondo J, Gomez-Gracia E, Fiol M, Lapetra J, Serra-Majem L, Munoz MA, Pinto X, Lamuela-Raventos RM, Basora J, Buil-Cosiales P, Sorli JV, Ruiz-Gutierrez V, Martinez JA, Salas-Salvado J. Olive oil intake and risk of cardiovascular disease and mortality in the PREDIMED Study. BMC Medicine. 2014 May 13;12:78. doi:10.1186/1741-7015-12-78
Why we cite it
Provides the olive oil-specific dose-response analysis from the PREDIMED trial, finding that the cardiovascular association is carried by extra-virgin olive oil rather than refined varieties, with a dose-response gradient.
**This is an observational analysis inside a randomised trial, and the distinction is the whole caveat.** Participants were randomised to **diet arms**; they were not randomised to olive-oil type or amount. Consumption was measured by a **137-item semiquantitative food frequency questionnaire** and analysed as **tertiles of baseline intake**, reported as hazard ratios — highest tertile **HR 0.65 (95% CI 0.47–0.89)** for total olive oil and **HR 0.61** for extra-virgin, among **7,216 participants** with 277 cardiovascular events and 323 deaths. **Observational associations within a trial population are not the trial's randomised result.** Directly relevant to the project because it distinguishes between types of olive oil — showing that quality (EVOO with its polyphenols) matters, not just the presence of olive oil in the diet — and provides concrete per-serving risk reductions useful for motivating specific food choices.