Mediterranean Diet and Monounsaturated Fat

A very big caveat that goes along with suggesting Americans would do well to substitute monounsaturated fat for saturated is that such advice doesn't address the epidemic of obesity in our country. Each tablespoon of olive oil, or any cooking oil for that matter, consists of 120 calories of pure fat. And unlike carbohydrates, any fat we eat, whether saturated or mono-unsaturated, is stored very efficiently as body fat. In other words, the more fat in your diet, the fatter you are likely to end up with even when calorie consumption stays the same. And with excess body fat comes an increased risk of high blood pressure, which is considered a major risk factor for developing heart disease in and of itself.

Excess body fat also keeps down HDL-cholesterol, and much more dramatically than not eating olive oil. That is, body weight is a much more powerful regulator of HDL levels than monounsaturated fat in the diet. The less heavy a person is (the closer to healthy weight), the higher his HDL levels will be.

Another more powerful regulator of HDL-cholesterol than the amount of olive oil one eats is exercise. Vigorous physical activity helps maintain high HDL levels (in part because it can help keep off excess pounds).

These are extremely important considerations, since HDL levels are important for most Americans. People in the U.S. tend not to go on diets so low in fat that it doesn't matter whether or not artery-clearing HDL-cholesterol is present. Unfortunately, they also tend not to exercise, which is one reason obesity is so prevalent here.

Even if Americans did engage in a great deal of physical activity and manage as a whole to keep their weight at healthy levels (which not only maintains higher HDL- but also keeps down LDL-cholesterol), it is not at all clear that olive oil would be the dietary fat of choice for staving off heart disease. After all, canola oil is also high in mono-unsaturated fat. What's more, it has less than half the saturated fat of olive oil. Yes, olive oil contains some saturates; every cooking oil does. A particular one may be referred to as monounsaturated because monounsaturated fatty acids make up the bulk of its composition. But it is actually a combination of different types of fatty acids.

Other cooking oils that might do the job of keeping heart disease at bay are corn, safflower, and sunflower oils, all of which are high in poly- rather than mono-unsaturates. Indeed, when Harvard University nutritional biochemists recently reviewed hundreds of studies that addressed the effect of various oils on blood cholesterol levels, he found a pattern that indicated polyunsaturated fatty acids actively lower blood cholesterol, particularly LDL-cholesterol, while mono-unsaturates do not.

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