Which is better: monounsaturated or polyunsaturated fats?

Both types of unsaturated fat-monounsaturated and polyunsaturated -can offer important health benefits. We know from studies involving the Mediterranean diet-where intake of olive oil is especially high -that monounsaturates can be heart protective. (Olive oil has the highest level of monounsaturated fat of any commonly used oil.) With polyunsaturates, there is also evidence of decreased risk of chronic disease, but only when the diet is also relatively high quality and accompanied by healthy intake of antioxidant nutrients.

The reason we need plenty of antioxidants when we eat polyunsaturates is simple: the more unsaturated a fat is, the more delicate it becomes. Heat and oxygen are more damaging to polyunsaturated fats than to monounsaturated ones. This situation is problematic for highly polyunsaturated plant oils because they have lost the antioxidant protection that was originally supplied by their whole food origins (i.e., beans, seeds, or nuts). At the World's Healthiest Foods, we encourage consumption of many whole foods that contain large amounts of polyunsaturated fat, but we do not encourage consumption of high-polyunsaturate oils that have been processed from these exact same foods! Oils processed from whole foods do not have the same protection from heat and oxygen that whole foods have-too many antioxidant nutrients have been lost during processing.

Due to the problems with heat damage to oils that are high in polyunsaturates, many companies offer oils that would ordinarily be high in polyunsaturates, but in fact contain much fewer-than-expected polyunsaturates and much higher-than-expected monounsaturates. These oils are produced from plants that have been hybridized (not genetically engineered) to contain more monounsaturated fat in their beans or seeds. Since most of this monounsaturated fat comes from oleic acid (one of the most common monounsaturated fatty acids found in food), these oils are usually called "high-oleic oils." You can buy high-oleic sunflower, safflower, and corn oil in many grocery stores. If you plan to use cooking oils at high heat, these high-oleic versions can be a good choice.

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