Olive oil has been researched with regard its beneficial effects on cardiovascular disease. While polyunsaturated fatty acids do appear to show some protective effects against cardiovascular disease, the cardioprotective effects of the monounsaturated fatty acids that predominate in olive oil are less clear. In fact it appears from research that most of the cardioprotective effects of consuming olive oil comes not from the fatty acids but the phytonutrients within the oil. These phytonutrients survive the oil processing steps and are then consumed along with the oil. That extra virgin olive oil is more beneficial than non-extra virgin olive oil supports this theory because extra virgin olive oil contain higher concentrations of these plant chemicals due to its less refined nature. Based on the logic that it is the phytonutrients within the olives rather than the oil itself that is cardioprotective, consuming whole olives as part of a high quality diet makes sense from a health perspective. Olives are likely protective of cardiovascular disease because they contain high levels of antioxidants.
The olive tree (Olea europaea) produces fruits which we call olives. Olives are commercially available as both green and black fruits, but they are infact the same produce at different degrees of ripeness. As the olive ripens it passes from green to black, and as such black olives are fully ripe while green olives are slightly unripe. Olives have a fat content of around 20 to 35 %, the oil containing high concentrations of the omega-9 fatty acid oleic acid (OA, C18:1 (n-9)). As with all plant material containing fatty acids, olives are also a good source of vitamin E, as this is used by the plant to protect the oils from rancidity. In addition, olive contain a number of phytochemicals including the phenolic terpene compounds oleuropein, tyrosol and hydroxytyrosol. These phytochemicals are bioavailable in humans and may have antioxidant effects. In particular the phenolic compounds in olives may prevent oxidative stress in the epithelial cells of arteries and this may in turn prevent the development of endothelial dysfunction and high blood pressure. Olives also contain melatonin, a signal molecule that induced sleep and relaxation in humans.