Avocados are rich sources of monounsaturated fatty acids, vitamins, minerals, fiber, phytosterols, and polyphenols. One fresh Hass avocado (∼136 g) contains ∼13 g monounsaturated fatty acids, 10 g fiber, and carotenoids, and other bioactive components. As a nutrient-dense source of monounsaturated fatty acids, avocados can be used to replace saturated fatty acids in a diet to lower low-density lipoprotein cholesterol (LDL-cholesterol). Here are a few studies that showed the effect of avocado consumption on cardiovascular disease risk factors.

    One study (1) aimed to assess the effects of replacing carbohydrate energy in meals with half or whole avocado on postprandial indices of metabolic and vascular health. The randomized, controlled, 3-arm, 6 hours, crossover study was conducted in overweight/obese middle-aged adults (n = 31). Participants consumed energy-matched breakfast meals containing 0 g (Control), 68 g (Half-Avocado), or 136 g (Whole-Avocado) fresh Hass avocado on 3 separate occasions.

    Post-avocado-meal glycemic (p < 0.0001), insulinemic (p < 0.0001) and flow-mediated vasodilation responses (p < 0.01) were reduced compared to Control meal, independent of avocado dose. Whole-Avocado meal resulted in lower concentrations of triglyceride-rich lipoproteins and higher concentrations of larger high-density lipoprotein (HDL) particles compared with the Control meal (p < 0.05). Oxidized low-density-lipoproteins, monocyte chemoattractant protein-1, and interleukin-6 were not different among meals. Tumor necrosis factor-α tended to be lower after Whole-Avocado meal vs. Control meal (p = 0.07) (1).

    Replacing carbohydrate components with avocados in a meal improved flow-mediated vasodilation (a measure of endothelial function), and improved glycemic and lipoprotein profiles in overweight/obese adults. The results also demonstrated reduced postprandial glycemia, including reduced peak glucose and insulin concentrations, along with increased vaso-relaxation when either a half or whole avocado was included in the meal compared to the Control meal with no avocado. These results suggested that incorporating avocado into a meal can have beneficial effects on glycemic and vascular markers during an acute postprandial challenge in middle-aged, overweight/obese adults (1).

    A randomized, crossover, controlled feeding trial (2) was conducted with 45 overweight/obese participants. Three cholesterol-lowering diets (6% to 7% Saturated Fatty Acids) were fed (5 weeks each diet): a lower-fat diet (24% fat); 2 moderate-fat diets (34% fat) provided similar foods and were matched for macronutrients and fatty acids: the avocado diet included one fresh Hass avocado (136 g) per day, and the moderate-fat diet mainly used high oleic acid oils to match the fatty acid content of one avocado.

    Compared with baseline, the reduction in low-density-lipoprotein (LDL) cholesterol and non-high-density lipoprotein (HDL) cholesterol on the avocado diet (-13.5 mg/dL, -14.6 mg/dL) was greater than the moderate-fat (-8.3 mg/dL, -8.7 mg/dL) and lower-fat (-7.4 mg/dL, -4.8 mg/dL) diets (p<0.05). Only the avocado diet significantly decreased LDL particle number (-80.1 nmol/L, p=0.0001), small dense LDL cholesterol (-4.1 mg/dL, p=0.04), and the ratio of LDL/HDL (-6.6%, p<0.0001) from baseline (2).

    Inclusion of one avocado per day as part of a moderate-fat, cholesterol-lowering diet has additional LDL-cholesterol, LDL-particle number, and non-HDL-cholesterol lowering effects, especially for small, dense LDL. These results demonstrate that avocados have beneficial effects on cardio-metabolic risk factors that extend beyond their heart-healthy fatty acid profile (2).

    Consumption of a daily meal with avocado may alter abdominal fat distribution, at least in females as shown in one study (3). A total of 105 adults aged 25-45 years old (61% female) with Body Mass Index (BMI) ≥25 kg/m2 were randomly assigned to an intervention (n = 53) that received a daily meal with 1 fresh Hass avocado or control (n = 52) that received an isocaloric meal with similar ingredients without avocado for 12 weeks. Abdominal adiposity [visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and the ratio of VAT to SAAT (VS Ratio)], fasted glucose and insulin, insulin sensitivity, and β-cell function were measured (3).

    The control group exhibited a greater reduction in subcutaneous abdominal adipose tissue SAAT [-54.5 ± 155.8 g (control) compared with 17.4 ± 155.1 g (treatment), p = 0.017] and increase in VS Ratio [0.007 ± 0.047 (control) compared with -0.011 ± 0.044 (treatment), p = 0.024]. Among females, the treatment group exhibited a greater reduction in visceral adipose tissue VAT [1.6 ± 89.8 g (control) compared with -32.9 ± 81.6 g (treatment), p = 0.021] and VS Ratio [0.01 ± 0.05 (control) compared with -0.01 ± 0.03 (treatment), p = 0.001]. Among males, there was no significant difference between groups in changes in abdominal adiposity or glycemic outcomes.

    Daily consumption of 1 fresh Hass avocado changed abdominal adiposity distribution among females but did not facilitate improvements in peripheral insulin sensitivity or β-cell function among adults with overweight and obesity. The change in visceral adipose tissue VAT among females in the treatment group in the study was ∼5% which was a modest change. Considering that the study was relatively short (3 months) and did not include an exercise component, the modest change in visceral adipose tissue is not surprising. It is possible that maintaining the treatment regimen for a longer period could have provided the necessary cumulative reduction in visceral adipose tissue to be clinically meaningful (3).

    Avocado is a well-known source of carotenoids, minerals, phenolics, vitamins, and fatty acids. A review paper showed that several studies reporting that avocado or avocado-enriched diet had significant lipid-lowering effects, specifically lowering triglyceride, total cholesterol, LDL-cholesterol, and increasing HDL-cholesterol. In addition to the lipid-lowering effect of avocado which is mainly attributed to its high monounsaturated fatty acid content, avocado has also been reported to have antihypertensive, antidiabetic, anti-obesity, antithrombotic, antiatherosclerotic, and cardioprotective effects (4).

    High levels of lipids (cholesterol, triglycerides, or both) carried by lipoproteins in the blood are risk factors of cardiovascular disease. The previous post on Two Apples a Day May Lower Cholesterol talked about apples’ benefits to lower cholesterol, now you may add another fruit with the cholesterol-lowering benefit into your diet: avocado.

 

References:

1. Eunyoung Park, Indika Edirisinghe, Britt Burton-Freeman.(2018). Avocado Fruit on Postprandial Markers of Cardio-Metabolic Risk: A Randomized Controlled Dose Response Trial in Overweight and Obese Men and Women. Nutrients, 10(9):1287.

2. Wang, L., Bordi, P. L., Fleming, J. A., Hill, A. M., & Kris-Etherton, P. M. (2015). 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. Journal of the American Heart Association, 4(1), e001355–e001355.

3. Naiman A Khan, Caitlyn G Edwards, Sharon V Thompson, Bridget A Hannon, Sarah K Burke, Anne D M Walk, Richard W A Mackenzie, Ginger E Reeser, Barbara H Fiese, Nicholas A Burd, and Hannah D Holscher. (2021). Avocado Consumption, Abdominal Adiposity, and Oral Glucose Tolerance Among Persons with Overweight and Obesity. J Nutr. 2021 Sep; 151(9): 2513–2521.

4. Tabeshpour, J., Razavi, B. M., & Hosseinzadeh, H. (2017). Effects of Avocado (Persea americana ) on Metabolic Syndrome: A Comprehensive Systematic Review. Phytotherapy Research, 31(6), 819–837.