Consumption of 1 avocado each day as part of a moderate-fat diet can lower low-density lipoprotein cholesterol (LDL-C) concentration and the number of low-density lipoprotein particles (LDL-P; determined by nuclear magnetic resonance) more so than a cholesterol-lowering low-fat diet or an avocado-free moderate-fat diet. The findings were presented by PhD candidate Li Wang, The Pennsylvania State University, University Park, Pennsylvania, USA.

Elevated LDL-C is a risk factor for cardiovascular disease and stroke. Avocados are a nutrient powerhouse that can lower LDL-C levels [Colquhoun DM et al. Am J Clin Nutr 1992; Lopez LR et al. Arch Med Res 1996; Pieterse Z et al. Nutrition 2005]. The number and size of LDL-P are also important in determining cardiovascular risk. Particles that are smaller and denser can more readily penetrate the arterial wall and promote plaque formation.

The study assessed 4 diets (Table 1). The 45 subjects were randomly assigned to initially receive a low-fat, moderate-fat, or avocado diet for 5 weeks, with subsequent 5-week diet periods with the remaining 2 diets. Each diet period was separated by a washout interval (Figure 1).

Clinical visit involving blood draw and monitoring of vital signs was performed at randomization and after each 5-week diet period. The subjects were 21 to 70 years of age, were healthy, and had a body mass index of 25 to 35 kg/m² and LDL-C in the 25th to 90th percentile. Exclusion criteria were history of cardiovascular disease or diabetes mellitus, blood pressure ≥ 140/90 mm Hg, and use of cholesterol-lowering medications or supplements. Baseline characteristics are summarized in Table 2.

All 3 diets lowered total cholesterol and LDL-C compared to baseline. The reduction of LDL-C on the avocado diet was greater than the moderate- and low-fat diets. Triglycerides, very-low-density lipoprotein cholesterol, and intermediate-density lipoprotein cholesterol were elevated in subjects on the low-fat diet. Both large and small subclasses of LDL-C decreased from baseline for all diets; however, only the avocado diet significantly decreased small, dense LDL-C (LDL₃₊₄). In addition, only the avocado diet significantly decreased LDL-P. The discordance between the change in LDL-C versus LDL-P by the low- and moderate-fat diets is due to their effects on small LDL-P. The moderate- and low-fat diets significantly increased small LDL-P, but the avocado diet did not.

The study supports the importance of a diet that includes an avocado per day for decreasing the risk of cardiovascular disease, and the benefit extends beyond the cholesterol-lowering fatty acid profile of avocados.