The olive (Olea europaea) was probably first cultivated in Crete around 3500 BC. The leaves have been used since those times to clean wounds. Olive leaves lower blood pressure and help to improve the function of the circulatory system. They are also mildly diuretic and may be used to treat conditions such as cystitis. Possessing some ability to lower blood sugar levels, the leaves have been taken for diabetes. The oil is nourishing and improves the balance of fats within the blood. It is traditionally taken with lemon juice in teaspoonful doses to treat gallstones. The oil has a generally protective action on the digestive tract and is useful for dry skin. Externally, it is a good, although sticky, carrier oil for essential oils. Main properties of olive: Digestive, diuretic, anti-inflammatory.