The differences between monounsaturated and polyunsaturated fats lie in their structures. Monounsaturated fats contain one double bond in their structures. On the other hand, polyunsaturated fats contain two or more double bonds in their structure.
Despite their slight differences in the chemical structure, both have been linked to promoting heart health by modestly increasing HDL cholesterol and helping to lower LDL cholesterol. In fact, replacing saturated fat and trans fats with foods containing mainly monounsaturated and polyunsaturated fats may help to protect you against heart disease. There is more evidence regarding this with polyunsaturated fats than monounsaturated fats.
The National Cholesterol Education Program (NCEP) recommends that monounsaturated fats should consist of up to 20% of your daily caloric intake. Foods high in monounsaturated fats include:
- olive oil
- canola oil
- avocados
- Nuts
- Seeds
- Vegetable oils (corn oil, safflower oil)
Sources:
Third Report of the National Cholesterol Education Program
(NCEP) Expert Panel on Detection, Evaluation, and Treatment of
High Blood Cholesterol in Adults (PDF), July 2004, The National Institutes of Heath: The National Heart, Lung, and Blood Institute.
Rolfes SR, Whitney E. Understanding Nutrition, 3rd ed 2005.

