Limiting high cholesterol foods and some types of fat helps to lower blood cholesterol levels, but adding certain fats to the diet may help even more. New research suggests that adding monounsaturated fat (MUFA) to a low-cholesterol diet may improve the success of the diet.

Monounsaturated fats are commonly found in a variety of plant foods such as nuts, seeds, avocados, and oils such as olive oil, canola oil, sunflower oil, and peanut oil.

Levels of HDL increased 12.5 percent while LDL levels decreased 35 percent in those who followed the high-MUFA diet.

People who have low levels of "good" HDL cholesterol and high "bad" LDL levels are at an increased risk for developing cardiovascular disease. Dietary recommendations for raising HDL have been few, but this research shows that when people eat a diet high in monounsaturated fats, levels of "good" or HDL cholesterol increase and levels of "bad" or LDL cholesterol decrease. To lower high LDL levels a person must also limit their intake of foods high in cholesterol, saturated fat, and trans fat.

Twenty-four patients with high cholesterol consumed a diet very low in saturated fat for one month before being assigned to a study diet. The randomized study assigned the 17 men and seven postmenopausal women who had mild to moderately high cholesterol levels to either a high-MUFA diet or a low-MUFA diet for one month.

The vegetarian diet included foods such as oats, barley, psyllium, eggplant, okra, soy, almonds and a margarine containing plant sterols. The researchers substituted 13 percent of carbohydrate calories with high-MUFA sunflower oil or avocado oil in the group on the high-MUFA diet.

Levels of HDL increased 12.5 percent while LDL levels decreased 35 percent in those who followed the high-MUFA diet. In those who consumed the low-MUFA diet, levels of HDL cholesterol did not change. Both diets resulted in lower LDL levels.

The traditional diets of countries in the Mediterranean region are good examples of the benefits of MUFA. Though fat intake is high in the region (40 percent or more of kcalories), the rate of heart disease is low. Previous research has attributed this to the frequent use of olives and olive oil.

The study researchers point out that exercise, moderate consumption of alcohol, not smoking, and weight loss are also effective ways to raise "good" HDL cholesterol.

The study was published in the November 1, 2010 issue of the Canadian Medical Association Journal.