Olive Leaf (<b><i>Olea europaea L. folium</i></b>): Potential Effects on Glycemia and Lipidemia

<b><i>Background:</i></b> Olive tree (<i>Olea europaea</i>, Oleaceae) leaves have been widely used in traditional herbal medicine to prevent and treat various diseases especially in Mediterranean countries. They contain several potentially bioactive compounds that may have hypoglycemic and hypolipidemic properties. <b><i>Summary:</i></b> The literature has recently been attempting to define the relationship between olive leaf (<i>Olea europaea L. folium</i>) polyphenols and a number of health problems. Oleuropein, the basic phenolic compound of olive leaf and its extract, is responsible for the characteristic bitter taste and unique aroma of olive fruits. Furthermore, it is shown that oleuropein and its hydrolyzed products have many beneficial effects on human health because of its antioxidant characters. A number of studies report that olive leaf has potentially positive effects on the parameters related to diabetes and cardiovascular diseases by various mechanisms. Besides, toxicity studies suggest that olive leaf is generally safe even at high doses. <b><i>Key messages:</i></b> Although current results obtained until today seem promising, the studies in this subject are usually on cell culture and animal trials. Moreover, mostly the extract forms of olive leaves are used in the studies. More randomized controlled human clinical trials with extensive toxicity studies are needed to evaluate potential health effects and safety.