Archeological records indicate that man has cultivated the olive tree for about 6,000 years; having been especially popular in the Isle of Crete (which as you recall, also appeared in the Seven Countries Study to be the site of the lowest incidence of heart disease). All oils that we use for eating and cooking contain “fat” and olive oil is no exception. However, it is mostly monounsaturated fat as opposed to saturated fat or hydrogenated fat. It can be used as a flavoring for cooking or in salad dressings or as a healthy substitute for butter or margarine. Several large population studies have confirmed that diets with higher amounts of fat of the monounsaturated type reduce total cholesterol and LDL [“bad”] cholesterol levels to the same degree as low fat, high-carbohydrate diets [such as the AHA Step I and II diets]. The additional benefit of olive oil is, as part of a Mediterranean type diet, is that it also has a favorable effect on lowering blood triglycerides [also a factor in heart disease] and maintaining HDL [“good” cholesterol].
In a published study, individuals were randomly assigned to one of three diets: a diet enriched with olive oil, an AHA Step II diet, or an average American control diet. The olive oil and Step II diets lowered total cholesterol and LDL cholesterol to the same degree. However, triglyceride levels fell 13% in patients on the olive oil diet and increased 11% in the Step II diet. HDL cholesterol levels were unchanged in the olive oil diet but decreased 4% in the Step II diet. Remember we want to keep the HDL up as high as possible to reduce heart disease.
Based upon the above information, the authors of the study estimated that the overall risk of cardiovascular disease was lowered by 25% by the olive oil diet and only 12% by the Step II diet. Please note that the cholesterol-lowering “statin” type drugs lower the risk for a heart attack by about 35%, which is not too much better than the “olive oil” diet alone. In subjects with elevated cholesterol who would benefit from the use of statin type medications, additional cardiovascular benefit would then be found by also following a diet with olive oil as a substitute for salad dressing, as a substitute for butter or margarine, and for cooking.
Olive oil apparently has other beneficial effects such as lowering blood pressure, inhibiting the oxidation of LDL cholesterol [the last step before it gets put into your arteries], providing anti-inflammatory effects, and improving insulin sensitivity.
The US Food and Drug Administration (FDA) has recently given manufactures of olive oil and some olive oil-containing food the green light to carry a statement about their potential heart benefits. The claim indicates evidence suggesting that about 2 tablespoons of olive oil per day may reduce the risk of a heart attack. However, to achieve this result, the olive oil should replace a similar amount of saturated fat and should not increase the total daily calories.
The strong taste of extra-virgin olive oil is partly because of the presence of a large amount of “flavonoids”, which account for its antioxidant properties that then reduce LDL oxidation. Other foods rich in flavonoids include berries, apples, onions, tea, and red wine (all of which have also been shown to be of benefit in reducing overall heart risk).