Do you like avocados? Most people do and the good news is that they are healthy for the heart. A study published by the Journal of the American Heart Association looked at avocados and unsaturated fat and their effect on blood cholesterol levels. The study was a randomized, crossover, controlled feeding trial conducted with 45 overweight individuals. Participants were first fed an “average American diet” high in saturated fat and cholesterol, for several weeks to establish a baseline to compare the effects of healthier diets on blood cholesterol levels.
The first diet was a low fat diet. Saturated fat was cut in half (13% of cal to 7%) and total fat levels were decreased from 34% of calories to 24%. They followed this diet for 5 weeks and then took blood samples to see changes in cholesterol levels.
Next they were fed a similar diet, protein, saturated fat, and cholesterol levels remained the same, but the total fat intake went up to 34% of the calories (similar to the average American diet). The added fat came primarily from Canola oil which is high in monounsaturated fatty acids (MUFAs). This diet was called the Moderate Fat Diet and was eaten for 5 weeks after which blood tests were done again.
The third diet as very similar to the moderate fat diet except the added fat came from avocados instead of added Canola oil. It was called the “Avocado Diet” and included a whole avocado daily. After another 5 weeks on this diet, they checked blood cholesterol levels again.
Here is what they found:
- On the Average American Diet, non-HDL cholesterol levels were 151 mg/dL. Non-HDL cholesterol is simply total cholesterol – HDL cholesterol. What is left includes all of the atherogenic cholesterol (LDL, VLDL, IDL cholesterol). New research suggests that non-HDL cholesterol is the best way to evaluate blood cholesterol levels for risk of coronary heart disease. Non-HDL cholesterol levels of 160 mg/dL or higher indicates increased risk; ideal is less than 130 mg/dL.
- On the “Low Fat Diet” non-HDL cholesterol (or bad cholesterol) fell by 5 mg/dL.
- On the “Moderate Fat Diet” non-HDL cholesterol dropped nearly twice as much, 9 mg/dL.
- But on the “Avocado Diet” non-HDL cholesterol dropped the most, 15 mg/dL, three times as much as on the low fat diet. The avocado diet also had a significant drop in small dense LDL cholesterol, the most dangerous form of cholesterol.
All three diets saw a drop in the bad cholesterol levels, but the moderate fat diets were both better at lowering cholesterol than the low fat diet. This finding reinforces the concept that to keep blood cholesterol levels low it is best to replace saturated fat with healthy fats (eg. fats high in unsaturated fatty acids) rather than with carbohydrates. Of the two unsaturated fat sources, avocados were the most effective. It also illustrates that whole foods high in healthy fats are preferable to refined fats as they add fiber, phytonutrients, and other key nutrients as well as a healthy fat.
The authors concluded, “Avocados have beneficial effects on cardio-metabolic risk factors.”
It’s best to use avocados in place of other less healthy fats and foods rather than just adding them in addition to what you already eat. Think of a variety of ways you can add avocados to your diet:
- Add avocado slices to sandwiches (perhaps in place of cheese)
- In salads
- Mashed and used as a spread or dip in place of fatty mayonnaise or sour cream
Reference: Journal of the American Heart Association 2015;4:e001355