Olive oil, a major component of the Mediterranean diet, has been associated in some small clinical trials and cross-sectional studies with a reduction in blood pressure. The objective of this study was to assess the association of olive oil consumption with the incidence of hypertension in an epidemiologic cohort, the Seguimiento Universidad de Navarra (SUN) study. The SUN Project is a prospective cohort study whose members are all university graduates. The recruitment and follow-up of participants is made using mailed questionnaires. Diet was assessed using a semiquantitative food frequency questionnaire previously validated in Spain, with 136 items. Outcomes of interest were newly diagnosed cases of hypertension, as reported by participants in the follow-up questionnaires. Logistic regression models were fit to assess the risk of hypertension associated with olive oil consumption. For the present analysis, we have taken in consideration the first 6,863 participants, with at least 2 yr of follow-up. After a median follow-up time of 28.5 mon, the cumulative incidence of hypertension was 4.7% in men and 1.7% in women. A lower risk of hypertension was observed among participants with a higher olive oil consumption at baseline, but the results were not statistically significant (P = 0.13 for the linear trend test in the multivariate model). However, among men, the adjusted odds ratios (OR) (95% confidence intervals) of hypertension for the second to fifth quintiles of olive oil consumption, compared with the first quintile, were 0.55 (0.28-1.10), 0.75 (0.39-1.43), 0.32 (0.15-0.70), and 0.46 (0.23-0.94), respectively (P = 0.02 for linear trend). No association was found between olive oil consumption and the risk of hypertension among women. In conclusion, in a Mediterranean population, we found olive oil consumption to be associated with a reduced risk of hypertension only among men. The lack of association observed among women might be attributed to the overall lower incidence of hypertension found among females and the resulting lower statistical power.
Bibliographical noteFunding Information:
We are indebted to the participants of the SUN study for their continued participation and cooperation. This work has been funded by the Department of Health of the Navarra Regional Government and by the Spanish Ministry of Health (Fondo de Investigaciones Sani-tarias, projects 01/0619, 03/0678, and G03/140, Red Tematica de Dieta y Enfermedad Cardiovascular). We would like to thank the other members of the SUN Study Group: J. de Irala, M. Seguí-Gómez, M. Bes-Rastrollo, R. Pajares, C. de la Fuente, M. Hernán-dez, C. Rubio, A. Sánchez-Villegas, F. Guillén-Grima, J.A. Martínez, and A. Martí.