Are There Heart-Healthy Benefits of Monounsaturated Fats?

Monounsaturated fatty acids (MUFA) have gained a reputation as being one of the “good fats"—that is, fats that are beneficial to health. While the scientific evidence is largely circumstantial, the idea that MUFA are important to good health—to general health as well as to cardiovascular health—now has strong support among many experts.

Olive oil being poured on a spoon
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What Are Monounsaturated Fatty Acids?

MUFA are one of the two types of unsaturated fatty acids. Unsaturated fatty acids have at least one double bond in the fatty acid carbon chain (as opposed to saturated fatty acids, which have no double bonds). The two types of unsaturated fatty acids are MUFA, which have one double bond in the chain; and polyunsaturated fatty acids (PUFA), which have two or more double bonds.

Both types of unsaturated fatty acids are thought to confer significant health benefits, though the scientific evidence is stronger for PUFA.

Health Benefits of MUFA

The evidence in favor of including MUFA in a heart-healthy diet is largely circumstantial. For instance, there are no randomized clinical studies showing that MUFA reduce the incidence of coronary artery disease (CAD).

Still, the circumstantial evidence is substantial.

MUFA have beneficial effects on blood lipids. They reduce LDL cholesterol levels (“bad” cholesterol) and increase HDL cholesterol levels (“good” cholesterol). They also decrease blood levels of triglycerides. So eating MUFA tends to produce a general improvement in the overall pattern of blood lipids that ought to be quite friendly to the cardiovascular system.

In addition, there is evidence that MUFA can help prevent the oxidation of LDL cholesterol particles. Oxidized LDL appears to play an important role in the formation of atherosclerotic plaques.

MUFA may be particularly helpful in people with type 2 diabetes or metabolic syndrome. In these patients, reducing PUFA in the diet and replacing them with MUFA has been shown to reduce insulin resistance, and improve the function of the blood vessels.

In a few studies, switching from PUFA to MUFA has also resulted in improved weight loss and reduced belly fat.

Because all this evidence is circumstantial, however, and has not been reproduced in large randomized clinical trials, dietary experts have not reached a consensus opinion on how much MUFA to recommend in our diets.

MUFA and the Mediterranean Diet

Perhaps the major reason MUFA have been “pushed” in recent years is due to the success of the Mediterranean diet. MUFA (in the form of olive oil) comprise an important part of the Mediterranean diet and are the chief source of fat in this diet.

In numerous clinical studies, a Mediterranean diet is strongly associated with a reduction in overall mortality, and also in mortality due to cardiovascular disease and to cancer (especially colon cancer, prostate cancer, and breast cancer). Heart attacks and strokes also appear to be diminished with the Mediterranean diet. Finally, this diet seems to correlate with a reduced incidence of Parkinson's disease and Alzheimer's disease.

The Mediterranean diet is high in fruits, vegetables, whole grains, nuts, and legumes— and lots of olive oil. Moderate amounts of poultry, fish, cheese, and red wine are also included. The one thing that particularly stands out with the Mediterranean diet, however, is the high consumption of olive oil, that is, of MUFA.In the opinion of most dietary experts, the fact that it includes a high intake of MUFA is one of the main reasons a Mediterranean diet appears to be so healthy.

Including MUFA in the Diet

Olive oil is the main dietary source of MUFA. Olive oil is liquid at room temperature but quickly turns solid when placed in a refrigerator. It can be used as a cooking oil if the heat is kept to moderate temperatures. Olive oil is often as a dipping oil, and can often be substituted for butter, gravies or sauces.

In addition to olive oil, MUFA are found in avocados, most nuts, canola and sunflower oils, and peanut butter.

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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.