The reserachers concluded that eating one avocado a day was associated with lower levels of bad cholesterol in overweight or obese adults after conducting a randomized, controlled feeding study.
“We were able to show that when people incorporated one avocado a day into their diet, they had fewer small, dense LDL particles than before the diet,” says distinguished professor of nutrition Penny Kris-Etherton in a release. “Consequently, people should consider adding avocados to their diet in a healthy way, like on whole-wheat toast or as a veggie dip.”
LDL particles are harmful as they promote buildup of plaque in the arteries, avocados help to do away with LDL particles that have been oxidized within the body; the process of oxidation is harmful to the body in the same way that oxygen can damage food, think of a sliced apple that eventually turns brown as an example.
“A lot of research points to oxidation being the basis for conditions like cancer and heart disease,” Kris-Etherton explains. “We know that when LDL particles become oxidized, that starts a chain reaction that can promote atherosclerosis, which is the build-up of plaque in the artery wall. Oxidation is not good, so if you can help protect the body through the foods that you eat, that could be very beneficial.”
Avocados have previously been shown to help reduce bad cholesterol, this study focused on whether they could also help to reduce the oxidized LDL particles. 45 adult participants who were either over weight or obese were involoved in this study. Participants followed an initial 3 week diet designed to mimic a typical American diet to put all of the participants beginning on similar nutritional footing. Each participant then took part in 5 weeks of three separate diets assigned in a random order: a low fat diet, a moderate fat diet, and a moderate fat diet including a daily avocado; while in the no avocado diets participants made up for the lack by consuming extra healthy fats designed to mimic the amount of monounsaturated fatty acids they contain.
Participants displayed significantly lower levels of oxidized LDL cholesterol after the 5 week avocado diet as compared to the beginning of the study, or after completing the other 2 diet assignments; there was a clear reduction in small dense oxidized LDL cholesterol particles, and after the avocado diet participants exhibited beneficial levels of lutein antioxidants.
“When you think about bad cholesterol, it comes packaged in LDL particles, which vary in size,” Kris-Etherton comments. “All LDL is bad, but small, dense LDL is particularly bad. A key finding was that people on the avocado diet had fewer oxidized LDL particles. They also had more lutein, which may be the bioactive that’s protecting the LDL from being oxidized.”
Because the moderate fat diet without avocado was designed to include the same amount of monounsaturated fatty acids the disparity results among the diets indicates that avocados must contain additional bio-actives that help to combat bad cholesterol, according to the researchers.
“Nutrition research on avocados is a relatively new area of study, so I think we’re at the tip of the iceberg for learning about their health benefits,” Kris-Etherton concludes. “Avocados are really high in healthy fats, carotenoids — which are important for eye health — and other nutrients. They are such a nutrient-dense package, and I think we’re just beginning to learn about how they can improve health.”
