Effect of a moderate fat diet with and without avocados on lipoprotein particle number, size and subclasses in overweight and obese adults: a randomized, controlled trial

Abstract

Background: Avocados are a nutrient-dense source of monounsaturated fatty acids (MUFA) that can be used to replace saturated fatty acids (SFA) in a diet to lower low density lipoprotein cholesterol (LDL-C). Well-controlled studies are lacking on the effect of avocado consumption on cardiovascular disease (CVD) risk factors.

Methods and results: A randomized, crossover, controlled feeding trial was conducted with 45 overweight or obese participants with baseline LDL-C in the 25th to 90th percentile. Three cholesterol-lowering diets (6% to 7% SFA) were fed (5 weeks each): a lower-fat diet (LF: 24% fat); 2 moderate-fat diets (34% fat) provided similar foods and were matched for macronutrients and fatty acids: the avocado diet (AV) included one fresh Hass avocado (136 g) per day, and the moderate-fat diet (MF) mainly used high oleic acid oils to match the fatty acid content of one avocado. Compared with baseline, the reduction in LDL-C and non-high-density lipoprotein (HDL) cholesterol on the AV diet (-13.5 mg/dL, -14.6 mg/dL) was greater (P<0.05) than the MF (-8.3 mg/dL, -8.7 mg/dL) and LF (-7.4 mg/dL, -4.8 mg/dL) diets. Furthermore, only the AV diet significantly decreased LDL particle number (LDL-P, -80.1 nmol/L, P=0.0001), small dense LDL cholesterol (LDL(3+4), -4.1 mg/dL, P=0.04), and the ratio of LDL/HDL (-6.6%, P<0.0001) from baseline.

Conclusions: Inclusion of one avocado per day as part of a moderate-fat, cholesterol-lowering diet has additional LDL-C, LDL-P, and non-HDL-C lowering effects, especially for small, dense LDL. Our results demonstrate that avocados have beneficial effects on cardio-metabolic risk factors that extend beyond their heart-healthy fatty acid profile.

Clinical trial registration url: http://www.clinicaltrials.gov. Unique identifier: NCT01235832.

Keywords: MUFA; avocados; cardiovascular disease; diet; fatty acids; lipids; lipoproteins.

Figure 1.

Study design: randomized, crossover controlled feeding. AAD indicates average American diet; AV, avocado diet; LF, lower‐fat diet; MF, moderate‐fat diet.

Figure 2.

Participant recruitment flow.

Figure 3.

Percent change in lipids, lipoproteins, and apolipoproteins (mean±SEM) from baseline. *Represents values that are significantly different from the baseline (P<0.05). Values with different letters (a, b, and c) are significantly different (Tukey post‐hoc test by SAS, P<0.05). AV indicates avocado diet; apoA1, apolipoprotein A1; apoB, apolipoprotein B; HDL‐C, high‐density lipoprotein cholesterol; IDL‐C, intermediate‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; LF, lower‐fat diet; MF, moderate‐fat diet; TC, total cholesterol; TG, triglycerides; VLDL, very‐low‐density lipoprotein.

Figure 4.

Change in LDL subclasses from baseline (mean±SEM). (A) Change in LDL subclasses cholesterol; (B) change in total, large and small LDL particle numbers. *Represents values that are significantly different from the baseline (P<0.05). Values with different letters (a, b, and c) are significantly different (Tukey post‐hoc test by SAS, P<0.05). AV indicates avocado diet; LDL‐C, low‐density lipoprotein cholesterol; LDL‐P, low‐density lipoprotein number; LF, lower‐fat diet; MF, moderate‐fat diet.

Figure 5.

(A) Correlation between the change in small LDL‐P and the change in total LDL‐P; (B) correlation between the change in large LDL‐P and the change in total LDL‐P; (C) correlation between the change in small LDL‐P and the change in LDL particle size; (D) correlation between the change in large LDL‐P and the change in LDL particle size. AV indicates avocado diet; LDL‐P, low‐density lipoprotein particle number; LF, lower‐fat diet; MF, moderate‐fat diet.

Figure 6.

(A) Correlation between the change in small LDL‐P and the change in LDL₃₊₄; (B) correlation between the change in large LDL‐P and the change in LDL₁₊₂. AV indicates avocado diet; LDL, low‐density lipoprotein; LDL‐P, low‐density lipoprotein particle number; LF, lower‐fat diet; MF, moderate‐fat diet.

Figure 7.

Change in VLDL and lipoprotein remnant particles—mean change value (±SEM) from baseline. (A) Change in VLDL and IDL subclasses cholesterol concentration; lipoprotein remnant particles consist of VLDL₃ and IDL. (B) Change in VLDL and IDL subclasses particle number. *Values are significantly different from the baseline (P<0.05). Values with different letters are significantly different (Tukey post‐hoc test by SAS, P<0.05). AV indicates avocado diet; IDL, intermediate‐density‐lipoprotein; IDL‐P, intermediate‐density‐lipoprotein particle number; LF, lower‐fat diet; MF, moderate‐fat diet; VLDL‐C, very‐low‐density lipoprotein cholesterol; VLDL‐P, very‐low‐density lipoprotein particle number.

Figure 8.

Correlations between LDL subclasses and TG, VLDL‐C, and HDL‐C. (A) Correlations between LDL₃₊₄ and TG, LDL₁₊₂ and TG; (B) correlations between LDL₃₊₄ and VLDL‐C, LDL₁₊₂ and VLDL‐C; (C) correlations between LDL₃₊₄ and HDL‐C, LDL₁₊₂ and HDL‐C. AAD indicates average American diet; AV, avocado diet; HDL‐C, high‐density lipoprotein cholesterol; LDL‐C, low‐density lipoprotein cholesterol; LF, lower‐fat diet; MF, moderate‐fat diet; TG, triglycerides; VLDL‐C, very‐low‐density lipoprotein cholesterol.