In ancient Greece, oil pressed from olives was a prevalent source of fat for the population and was widely used because of the absence of butter. It was used in cooking as well as spread on bread. The nutritional value of olive oil has been proven today. Because of its high content of unsaturated fat and antioxidants, it lowers the rate of heart disease. Unsaturated fats have been proven to lower the amount of LDL (low density lipoprotein) and increase the number of HDL (high density lipoprotein). The ancient Greek diet, being high in HDLs, cleansed the body of negative cholesterol buildup, and led to their low incidence of heart disease.