London, August 30 (IANS) Want to keep your heart healthy? Eating dark chocolates enriched with extra virgin olive oil may boost the level of "good" cholesterol as well as lower blood pressure -- both known risk factors for cardiovascular diseases, researchers say. The study showed that eating dark chocolates with olive oil every day also significantly raises the level of endothelial progenitor cell (EPC) -- critical for blood vessel repair and function. "We found that small daily portions of dark chocolate with added natural polyphenols from extra virgin olive oil was associated with an improved cardiovascular risk profile," said lead author Rossella Di Stefano, cardiologist at the University of Pisa, Italy. "Our study suggests that extra virgin olive oil might be a good food additive to help preserve our 'repairing cells', the EPCs," Stefano added. For the study, presented at the European Society of Cardiology Congress in Barcelona, the team tested volunteers with at least three cardiovascular risk factors (smoking, dyslipidaemia, hypertension or family history of cardiovascular disease) who received 40 grams of dark chocolate daily for 28 days. It contained 10 per cent extra virgin olive oil for 14 consecutive days and it contained 2.5 per cent Panaia red apple -- having high levels of polyphenols and antioxidants -- for the next 14 days. Polyphenols and antioxidants are known to reduce the risk of atherosclerosis progression and other cardiovascular diseases. Progression of atherosclerosis was assessed by metabolic changes (levels of carnitine and hippurate), lipid profile, blood pressure and levels of circulating endothelial progenitor cells (EPCs). EPCs are critical for vascular repair and maintenance of endothelial function. After 28 days, the researchers found that the chocolate enriched with olive oil was associated with significantly increased EPC levels and decreased carnitine and hippurate levels compared to both baseline and after consumption of apple-enriched chocolate. There was a non-significant decrease in triglyceride levels with apple-enriched chocolate, the researchers said.