Olive oil and its phenolic compounds, oleuropein and cafeic acid, have been shown in previous studies to exert anti-diabetic, anti-atherosclerotic and anti-inflammatory properties, the underlying mechanism of which is thought to be the antioxidant activity of olive oil.  Geovana Ebaid, from Sao Paulo State University (Brazil), and colleagues investigated the effects of olive oil, oleuropein, and cafeic acid, on calorimetric parameters, myocardial oxidative stress and energy metabolism in cardiac tissue in a rat model of obesity.  Obese rats supplemented with olive oil, oleuropein, and cafeic acid had higher oxygen consumption, increased fat-oxidation, and lower carbon dioxide production than non supplemented obese rats. As well, antioxidant enzymes were unaffected by olive oil and its compounds in the obese rats, but increased in non-obese olive oil and oleuropein supplemented rats. After 42 days, researchers found energy expenditure, oxygen consumption, and fat-oxidation were lower in obese rates group than in the non-obese control group. The researchers conclude that: “The present study demonstrated for the first time that olive-oil, oleuropein and cafeic-acid enhanced fat-oxidation and optimized cardiac energy metabolism in obesity conditions.”

Ebaid GM.X., Seiva FR.F., Rocha KK.H.R., Souza GA., Novelli EL.B. “Effects of olive oil and its minor phenolic constituents on obesity-induced cardiac metabolic changes.”  Nutrition Journal 2010, 9:46, 19 October 2010.