University at Buffalo Study Ties Olive Oil to Lower Blood Pressure and Glucose Levels

Buffalo, N.Y. - Researchers at the State University of New York at Buffalo have reported that in addition to affecting cholesterol levels, consumption of olive oil and butter correlates with blood pressure and blood glucose levels.

The UB researchers and colleagues in Italy found an inverse relationship between consumption of olive oil and measurements of cholesterol, blood pressure and blood glucose levels.

On the other hand, increased consumption of butter and margarine resulted in a higher reading for each of the three.

The study, reported in the Feb. 2 issue of the Journal of the American Medical Association, was conducted in conjunction with Italian researchers affiliated with the Italian Nine Communities Study of risk factors for atherosclerosis.

Results were based on analysis of data derived from dietary interviews and physical examinations conducted with 4,903 Italian adults ages 20 to 59. The subjects included 2,365 men and 2,538 women. The data were collected by the Italian study and analyzed by the UB researchers.

It is the first large population study of the association of consumption of monounsaturated fat with coronary heart disease risk factors, according to Maurizio Trevisan, M.D., principal author and associate professor of social and preventive medicine in the UB School of Medicine and Biomedical Sciences.

Trevisan noted that while there has been intensive investigation of the beneficial effects of use of olive oil and other monounsaturated oils in the diet on cholesterol levels, data on the impact on blood pressure and glucose levels have been limited.

"The strength of this study," the authors wrote, "lies in the available measure of cardiovascular risk factors in a large population sample exhibiting considerable variation in intake of monounsaturated, polyunsaturated and saturated fats. Because of this variation, we were able to find relatively strong associations despite a relatively crude measurement of dietary intake."

They added, however, that "the cross-sectional nature of this study needs to be taken into account in analysis of these findings. While the results are suggestive of a protective role for unsaturated fats for cardiovascular risk factors, other unmeasured confounders may be the actual etiologic agents."

Trevisan said that in their analyses, the researchers took into consideration confounding effects of other risk factors for cardiovascular disease, such as age, body-mass index, alcohol intake, smoking and consumption of fatty foods.

The authors noted that "Italy is particularly well-suited to an inquiry of this kind because of the frequent consumption of monounsaturated fat as well as the high variability in type and amount of fat consumption by Italians."

They found large regional variations in the consumption of butter and olive oil. While a large percentage of the population used olive oil, approximately 50 percent reported no use of butter.

The study found that "in both sexes, higher consumption of butter and margarine was associated with increased systolic and diastolic blood pressures and increased serum cholesterol levels; these associations reached statistical significance only in men. In both sexes, higher frequency of consumption of butter and margarine was associated with significantly higher levels of blood glucose."

Increased consumption of olive oil, they wrote, "was associated with significantly lower levels of systolic blood pressure, blood glucose and blood cholesterol in both sexes. In men but not in women, diastolic pressure was significantly negatively associated with olive oil consumption.

While the study found that consumption of polyunsaturated fats other than olive oil correlated with consistent and statistically significant lower cholesterol and blood glucose levels, the association was not consistent for blood pressure.

Other UB researchers participating in the study were Vittorio Krogh, M.D.; Jo Freudenheim, Ph.D.; and Alma Blake, Ph.D. The Italian researchers included Paola Muti, M.D.; Salvatore Panico, M.D.; Eduardo Farinaro, M.D.; Mario Mancini, M.D.; Alessandro Menotti, M.D.; and Giorgio Ricci, M.D.