New Clue to Why Avocados are Good for Heart Health

Published 14 November 2019 | Article based on a press release from Penn State university

Key Takeaways

• One avocado a day helps lower 'bad' cholesterol for heart healthy benefits
• Avocado lowers the level of oxidised LDL* in the blood
• LDL ('bad' choloesterol), in particular oxidised LDL, is known to promote the build-up of plaque in artery walls (atherosclerosis)

New research from Penn State University suggests that eating one avocado a day may help keep "bad cholesterol" at bay.

Researchers found that eating one avocado a day was associated with lower levels of LDL (specifically small, dense LDL particles) and oxidized LDL in adults with overweight or obesity.

"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," said Penny Kris-Etherton, distinguished professor of nutrition.

She added that small, dense LDL particles are particularly harmful for promoting plaque build-up in the arteries.

"Consequently, people should consider adding avocados to their diet in a healthy way, like on whole-wheat toast or as a veggie dip."

Specifically, the study found that avocados helped reduce LDL particles that had been oxidized.

Similar to the way oxygen can damage food -- like a cut apple turning brown -- the researchers said oxidation is also bad for the human body.

"A lot of research points to oxidation being the basis for conditions like cancer and heart disease," Kris-Etherton said.

"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."

While previous research demonstrated that avocados could help lower LDL cholesterol, Kris-Etherton and her colleagues were curious about whether avocados could also help lower oxidized LDL particles.

The Study

The researchers recruited 45 adult participants with overweight or obesity for the study.

All participants followed a two-week "run-in" diet at the beginning of the study. This diet mimicked an average American diet and allowed all participants to begin the study on similar nutritional "footing."

Next, each participant completed five weeks of three different treatment diets in a randomized order.

Diets included:

• a low-fat diet
• a moderate-fat diet
• a moderate-fat diet that included one avocado a day

The moderate-fat diet without avocados was supplemented with extra healthy fats to match the amount of monounsaturated fatty acids that would be obtained from the avocados.

The Results

After five weeks on the avocado diet, participants had significantly lower levels of oxidized LDL cholesterol than before the study began or after completing the low- and moderate-fat diets.

Participants also had higher levels of lutein, an antioxidant, after the avocado diet.

Researchers Comments

Kris-Etherton said there was specifically a reduction in small, dense LDL cholesterol particles that had become oxidized.

"When you think about bad cholesterol, it comes packaged in LDL particles, which vary in size," Kris-Etherton said.

"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."

The researchers added that because the moderate-fat diet without avocados included the same monounsaturated fatty acids found in avocados, it is likely that the fruit has additional bioactives that contributed to the benefits of the avocado diet.

WLR Comment

Avocado's are a tasty and satisfying food to include in your diet. They can be something of an acquired taste, but once you start trying them in different dishes and combinations, it's easy to get hooked.

They are high in fibre and healthy fats and have a low glycaemic index of 45, so are good for keeping you fuller for longer.

However, healthy fats have the same amount of calories as those that are less healthy, so avocados are high in calories compared to other fruits and vegetables.

Since avocado is normally served in halves, the number of calories in a portion is 138. (A whole avocado has 276 calories.)

That doesn't mean you shouldn't include plenty of avocados in your diet but, if you're trying to lose weight, it's important to be aware of the calories.

Here's some tasty, calorie counted, ideas for meals with avocado:

• Healthy Avocado Salad With Cooked Prawns
• Avocado, Tomato & Mozzarella Salad with Pomegranate Seeds
• Prawn and Avocado Cocktail

*LDL cholesterol stands for low-density lipoprotein cholesterol, often referred to as 'bad' cholesterol. High LDL levels are associated with an increased risk of cardiovascular disease³

Sources and References

1. Press Release: One avocado a day helps lower 'bad' cholesterol for heart healthy benefits, Penn State
2. Li Wang, Ling Tao, Lei Hao, Todd H Stanley, Kuan-Hsun Huang, Joshua D Lambert, Penny M Kris-Etherton. A Moderate-Fat Diet with One Avocado per Day Increases Plasma Antioxidants and Decreases the Oxidation of Small, Dense LDL in Adults with Overweight and Obesity: A Randomized Controlled Trial. The Journal of Nutrition, 2019; DOI: 10.1093/jn/nxz231
3. Medical Definition of LDL cholesterol MedicineNet