IRVINE, Calif. - Jan.7, 2015 - A moderate fat diet that includes one fresh avocado daily showed greater improvement in certain blood lipid markers when compared to an energy matched moderate fat diet without avocado or a low fat diet without avocado, according to new research published in the Journal of the American Heart Association.
Elevated cholesterol in the blood can increase risk factors for cardiovascular disease, the number one cause of death in the United States. A heart healthy diet can play an important role in keeping your cholesterol levels within a normal range. For example, the 2010 Dietary Guidelines for Americans recommends limiting saturated fat and replacing it with unsaturated fats and increasing your intake of fruits and vegetables.
The research, "The Effect of a Moderate Fat Diet With and Without Avocados on Lipoprotein Particle Number, Size and Subclasses in Overweight and Obese Adults - A Randomized, Controlled Trial," conducted at Pennsylvania State University, evaluated whether incorporating one fresh avocado into the diet daily for five weeks could reduce bad cholesterol levels more than a diet that incorporated monounsaturated fat from vegetable oils high in oleic acid as a substitute for one fresh avocado. The diets were matched for calories and macronutrients, but not for fiber, phytosterols, or other bioactives.
The researchers found that only the avocado diet significantly improved the ratio of total cholesterol to HDL, or "good" cholesterol (TC-HDL/C) and the ratio of LDL, or "bad" cholesterol, to HDL-cholesterol (LDL-C/HDL-C). The low fat diet did not reduce these ratios, and the reduction with the avocado diet was significantly greater than with the moderate fat diet. Additionally, the avocado diet achieved the greatest reduction in LDL-cholesterol compared to the low fat diet and moderate fat diet without avocados.
The study offers several possible explanations as to why the moderate fat diet with avocado had a more beneficial effect on certain biomarkers than the moderate fat diet without avocado, one of which may be the unique combination of vitamins, minerals, fiber, phytosterols, and other dietary bioactives that avocados provide that were not present in the other two diets. One fact worth noting is that the diet that included avocado provided 35 percent more fiber than the diets without avocado. Furthermore, these results are based on the consumption of one whole avocado each day. Additional research is needed to determine whether the results could be replicated with consumption of the recommended serving size of 1/5 of an avocado per day.
"The results of this study suggest that the monounsaturated fat, fiber, phytosterols and other dietary bioactives in avocados may provide greater benefits to cardiovascular disease risk factors compared to a calorie matched low fat diet," said Penny Kris-Etherton, Ph.D., RD, lead author of the study who is an expert in cardiovascular nutrition and Distinguished Professor at the Pennsylvania State University. "Furthermore, using novel advanced lipid testing methods, this study demonstrated that consumption of one avocado a day may affect atherogenic lipoprotein particle numbers (APL)."
While the conclusions drawn are from a single study that cannot be generalized to all populations, the study does provide further insights on the monounsaturated fat, fiber, phytosterols and other bioactives in avocados that may have a positive effect on CVD biomarkers such as LDL cholesterol in healthy overweight and obese adults. "Avocados, which contain naturally good fats, are a versatile, cholesterol-free and nutrient-dense fruit that can fit into a full range of healthy eating plans. Now we're adding to the body of evidence suggesting a relationship between avocados and heart health," said Emiliano Escobedo, executive director of the Hass Avocado Board, which underwrote the study.
To view the abstract or the published article, visit http://jaha.ahajournals.org/content/4/1/e001355.full.
About the Study
The study was based on a randomized, cross-over, controlled feeding trial on 45 healthy overweight or obese men and women. As a baseline before beginning the study diet, subjects followed a typical American diet for two weeks that was high in saturated fat. Next, participants followed three different calorie controlled diets for five weeks each that replaced a percentage of saturated fat in the American diet as follows:
- Low fat diet: 6 to 7 percent of energy from saturated fat from the typical American diet was replaced with complex carbohydrates mainly from grains.
- Moderate fat diet: 6 to 7 percent of energy from saturated fat from the typical American diet was replaced with monounsaturated fat mainly from high oleic acid oils (sunflower oil and canola oil) and some low-fat dairy products.
- Avocado diet: Similar to the moderate fat diet, but 6 to 7 percent of energy from the saturated fat was replaced with monounsaturated fat mainly from one fresh avocado daily (~ 136 g, without skin and seeds).
About the Hass Avocado Board
The Hass Avocado Board (HAB) is an agriculture promotion group established in 2002 to promote the consumption of Hass Avocados in the United States. A 12-member board representing domestic producers and importers of Hass Avocados directs HAB's promotion, research and information programs under supervision of the United States Department of Agriculture. Funding for HAB comes from Hass avocado producers and importers in the United States.
In 2010, HAB established a nutrition research program to increase awareness and improve understanding of the unique benefits of avocados to human health.
For a comprehensive collection of published nutrition and scientific literature, authoritative reports and other articles on or related to avocados, their nutrients and eating patterns that include them, visit avocadonutritioncenter.com.
Journal of the American Heart Association