Avocados are known to be a nutrient-dense food, high in beneficial monounsaturated fatty acids, but new research from Penn State indicates that eating one every day may lower bad cholesterol, which reduces risk for heart disease.

Previous studies have suggested that avocados are a cholesterol-lowering food, but this may be the first study that looked at specific health implications of adding the fruit to your diet.

Penny M. Kris-Etherton, Distinguished Professor of Nutrition at Penn State tested three different diets, all designed to lower cholesterol: a lower-fat diet, consisting of 24 percent fat, and two moderate fat diets, with 34 percent fat. The moderate fat diets were nearly identical, however one diet incorporated one Hass avocado every day while the other used a comparable amount of high oleic acid oils — such as olive oil — to match the fatty acid content of one avocado. (Hass avocados are the smaller, darker variety with bumpy green skin and the most commonly sold. They have a higher nutrient content than Florida avocados, which are larger, and have smoother skin and a higher water content.)

The avocado diet decreased bad cholesterol by 13.5 mg/dL, while LDL was decreased by 8.3 mg/dL on the moderate-fat diet and by 7.4 mg/dL on the low-fat diet.

All participants followed each of the three diets for five weeks. They were given a two-week break in between each diet. Blood samples were taken at the beginning and end of each study period. Subjects were randomly assigned the order in which they received each diet.

The study was published on Jan. 7 in the Journal of the American Heart Association.

"This was a controlled feeding study, but that is not the real world — so it is more of a proof-of-concept investigation," said Kris-Etherton. "We need to focus on getting people to eat a healthy diet that includes avocados and other food sources of better fats."

She pointed out that much of the U.S. population doesn't know how to use or prepare avocados, with the exception of guacamole. However, guacamole is usually eaten with corn chips, which are high in both sodium and calories.

"People should start thinking about eating avocados in new ways," said Kris-Etherton. "I think using it as a condiment is a great way to incorporate avocados into meals — for instance, putting a slice or two on a sandwich or using chopped avocado in a salad or to season vegetables."

Kris-Etherton and colleagues note that further research will need to be conducted with a larger and more diverse study sample and to explore further how high-density lipoproteins — good cholesterol — might be affected by a diet that includes avocados.

The Hass Avocado Board, the National Center for Research Resources, and the National Center for Advancing Translational Sciences all supported this research. But, Kris-Etherton told NPR News that her team would have published the results whatever the outcome would have been, and the Hass Board had no role in the design of the study or the final report.

(Edited from an article originally published by Penn State)