Good news for avocado lovers: Eating one avocado a day may have beneficial effects on the heart, according to a randomized, controlled study in the Journal of Nutrition last October authored by a renowned nutrition expert at Pennsylvania State University, Penny M. Kris-Etherton, Ph.D.
The study included 45 overweight or obese adults with high LDL (“bad”) cholesterol who ate three different cholesterol-lowering diets for five weeks each in randomized order: a low-fat diet (24 percent calories from fat); a moderate-fat diet (34 percent calories from fat) that included a daily avocado (rich in monounsaturated fats); and a moderate-fat diet that provided the same type and amount of monounsaturated fatty acids (oleic acid) as the avocado diet but from other sources. All participants followed a typical American diet for two weeks before starting the experimental diets.
Compared to baseline and the other diets, the avocado diet lowered levels of small, dense LDL particles, which are a risk factor for atherosclerosis. Moreover, the diet reduced levels of oxidized LDL (oxLDL) cholesterol in the blood, which is also considered an independent risk factor for cardiovascular disease. And this benefit “does not appear to be due to fatty acids since the moderate-fat diet with a matched fatty acid profile did not lower oxLDL,” the researchers noted. Rather, the protective effects were attributed to other bioactive compounds in avocados including polyphenols, phytosterols, and fiber.
Previous research at Penn State demonstrated that avocados can lower LDL cholesterol, especially small, dense LDL, as part of a moderate-fat, cholesterol-lowering diet. LDL cholesterol is harmful, but small, dense LDL particles are particularly dangerous because they are better able to get into artery walls where plaque forms, thus promoting atherosclerosis. They are also more easily oxidized, and oxidized LDL plays an important role in atherosclerosis. In addition, they are less easily cleared from the bloodstream. As the latest study noted, its findings provide “new evidence for an important role of avocado bioactives (in addition to the beneficial effects of their fatty acid profile) in affecting the atherogenicity of LDL, which may confer additional benefits to CVD risk control beyond the LDL cholesterol reductions.”
If you add avocados to your diet, be sure to compensate for their calories (about 225 to 365 calories each, depending on the size and variety) elsewhere, and eat them in place of less-healthful foods such as butter, cream cheese, and other spreads high in saturated fat. The study was supported by a grant from the Hass Avocado Board.