Avocado Consumption for 12 Weeks and Cardiometabolic Risk Factors: A Randomized Controlled Trial in Adults with Overweight or Obesity and Insulin Resistance

Avocado intake and cardiometabolic risk factors in a representative survey of Australians: a secondary analysis of the 2011-2012 national nutrition and physical activity survey

BACKGROUND

Avocados are a rich source of nutrients including monounsaturated fats, dietary fibre and phytochemicals. Higher dietary quality is reported in studies of consumers with higher avocado intakes. The present study aimed to examine avocado consumption and cardiometabolic risk measures in a representative sample of Australian adults.

METHODS

A cross-sectional analysis was performed using Australian Health Survey 2011-2013 (n = 2,736 observations). Day 1 24-hour recall data was used to examine reported avocado intake (whole avocados and avocado-containing products excluding avocado oil) and cardiometabolic risk measures (LDL, HDL, and total cholesterol, triglycerides, apolipoprotein B, HbA1c, plasma glucose, systolic and diastolic blood pressure). T-tests and chi square analyses were conducted between low (5.21 [95% CI: 4.63, 5.79] grams/day) and high (44.11 [95% CI: 35.89, 52.33] grams/day) consumers of avocado.

RESULTS

14.7% of Australians were 'avocado consumers' (n = 403 observations). Mean avocado intake was 24.63 (95% CI: 20.11, 29.15) grams per day, with a median intake of 10.40 (IQR: 4.49-26.00) grams per day for those considered 'avocado consumers'. Consumers of avocados had a lower BMI and waist circumference (each, p ≤ 0.001), lower plasma glucose level (p = 0.03), and higher HDL cholesterol (p ≤ 0.001) when compared with non-consumers. A trend towards lower plasma glucose, HbA1c (each, p = 0.04) and higher dietary fibre intake (p = 0.05) was found between high and low consumers of avocado.

CONCLUSIONS

Our study suggests favourable outcomes for avocado intake and cardiometabolic characteristics of consumers. Future studies should explore glucose homeostasis using a clinical trial design to understand potential relationships between avocado intake and cardiometabolic risk factors.

High dietary intake of unsaturated fatty acids is associated with improved insulin resistance - a cross-sectional study based on the NHANES database

BACKGROUND

A moderate intake of unsaturated fatty acids (UFA) is associated positively with improved insulin resistance. The aim of this study was to investigate the relationship between the dietary intake of unsaturated fatty acids/total fats (UFA/TF) and insulin resistance.

METHODS

15,560 participants were selected from the National Health and Nutrition Examination Survey (NHANES) database enrolled between March 2017 and 2020, and excluded those under 20 years of age, pregnant, or with missing data for key research items. Finally, 7,630 participants were included in the study. R software was used for data analysis that included: (1) general descriptive statistics; (2) comparison of differences in baseline information of three UFA/TF groups, namely low, medium, and high ratios; (3) calculation of the correlation between the UFA/TF ratio and markers of insulin resistance: triglyceride-glucose index (TyG) and homeostatic model assessment for insulin resistance (HOMA-IR); (4) stratification of the study subjects into two groups, with or without insulin resistance, using a cut-off value of HOMA-IR ≥ 2, followed by logistic regression analysis to examine the relationship between UFA/TF and insulin resistance status in the two groups; and (5) further stratification of the subjects according to age, gender, body mass index (BMI), race, total energy intake, total protein, total carbohydrate, total sugars, total dietary fiber, total fat, alcohol consumption, diabetes, hypercholesterolemia to analyze the impact of UFA/TF on insulin resistance status in different subgroups.

RESULTS

(1) A high UFA/TF level was associated with a low TyG index and HOMA-IR [β (vs. TyG index) = -0.559, 95% CI: (-0.821~-0.297), P < 0.001; β (vs. HOMA-IR) = -0.742, 95% CI: (-1.083~-0.402), P < 0.001]. This negative relationship became more pronounced when UFA/TF exceeded 57.9% (i.e., the higher group). (2) Logistic regression analysis showed that a higher UFA/TF level was associated with a lower risk of developing insulin resistance [Q3 vs. Q1: 0.838 (95%CI: 0.709 ~ 0.991); P for trend = 0.038]. After adjusting for covariates such as gender, age, and BMI, this protective effect remained significant (P value < 0.05). (3) Analysis also showed that increased UFA/TF intake reduced the risk of developing insulin resistance (OR = 0.266, 95% CI: (0.075 ~ 0.946), P = 0.041). Subgroup analysis showed that although elevated UFA/TF intake showed no statistically significant difference in its effect in most subgroups, the large study population in this study provides valuable insights on potential changes. Increased UFA/TF intake may confer relatively greater benefits within specific subgroups, particularly among the elderly [Q3 age group, OR = 0.114, 95%CI: (0.012 ~ 1.078), P = 0.058], females [OR = 0.234, 95%CI: (0.041 ~ 1.333), P = 0.102], those with a BMI ≤ 25 kg/m²[OR = 0.191, 95%CI: (0.016 ~ 2.344), P = 0.196], and individuals without hypercholesterolemia [OR = 0.207, 95%CI: (0.042 ~ 1.013), P = 0.0519]. The impact of high UFA/TF levels within subgroups based on the presence or absence of coronary heart disease and stroke displayed contrasting trends. In those without coronary heart disease, there was a significant protective effect against insulin resistance [OR = 0.254, 95% CI: (0.07 ~ 0.929), P = 0.0384], while in the stroke subgroup, a significantly protective effect against insulin resistance was observed [OR = 0.002, 95%CI: (0 ~ 0.695), P = 0.0376].

CONCLUSION

A high dietary intake of UFA relative to total fat consumption could be a protective factor against the risk of developing insulin resistance.

The effects of mango consumption on vascular health and immune function

Objectives

Heart disease, caused by atherosclerosis, is the leading cause of death. Maintaining vascular integrity is crucial to reducing atherosclerosis risk. Mangos are rich in fiber, vitamins, minerals, and phytochemicals that may offer cardioprotective and immune-boosting benefits. However, their effects on the vasculature and immune system in adults with overweight and obesity remain unclear. The objective of this study was to investigate the effects of mango consumption on vascular health and immune function in adults with overweight and obesity.

Methods

In a 12-week, crossover study, 27 overweight and obese participants consumed either 100 kcals of mangos daily or isocaloric low-fat cookies daily. Fasting blood samples were collected at baseline, week 4, and week 12 and analyzed for vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), P-selectin, E-selectin, sCD4, sCD8, sCD3E, and sCD45, tumor necrosis factor-alpha (TNF-α), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD).

Results

Mango consumption significantly decreased VCAM-1 between baseline and week 4 (P = 0.046) and week 12 (P = 0.004). CAT increased between baseline and week 12 (P = 0.035) with mango consumption. GPx increased at week 12 compared to baseline and week 4 (P < 0.05). At week 12, SOD was higher after mango consumption compared to low-fat cookie consumption (P = 0.046). There were no significant differences in ICAM-1, P-selectin, E-selectin, sCD4, sCD8, sCD3E, sCD45 or TNF-α concentrations (P > 0.05 for all non-significant results).

Conclusions

This study suggests that 100 kcals of mangos may benefit the integrity of the vasculature by reducing VCAM-1 and increasing SOD, CAT, and GPx levels. Mangos can be an alternative snack for improving atherosclerosis and oxidative stress risk factors.

Effects of an Unripe Avocado Extract on Glycaemic Control in Individuals with Obesity: A Double-Blinded, Parallel, Randomised Clinical Trial

BACKGROUND

Unripe avocados (Persea americana) are naturally enriched in mannoheptulose (MH), which is a candidate caloric restriction mimetic.

OBJECTIVES

To evaluate the effects of a diet supplement made from unripe avocado on glucose tolerance, and cardiometabolic risk factors in free-living nondiabetic adults with obesity.

METHODS

In a double-blinded, randomised controlled trial, 60 adults (female n = 47, age 48 ± 13 years, BMI 34.0 ± 2.6 kg/m2) were stratified by sex and randomised to avocado extract (AvX, 10 g finely ground, freeze-dried unripe avocado) or placebo (10 g finely ground cornmeal plus 5% spinach powder) daily, for 12 weeks. The primary outcome was a change in glucose area under the curve (AUC) in response to a 75 g oral glucose tolerance test. A post-hoc analysis was subsequently performed in a subgroup with insulin AUC above the median of baseline values after removal of participants >2 SD from the mean.

RESULTS

There were no between-group differences in glucose AUC (p = 0.678), insulin AUC (p = 0.091), or cardiovascular outcomes. In the subgroup analysis, insulin AUC was lower in AxV versus placebo (p = 0.024).

CONCLUSIONS

Daily consumption of unripe avocado extract enriched in MH did not alter glucose tolerance or insulin sensitivity in nondiabetic adults with obesity, but the data provided preliminary evidence for a benefit in insulin AUC in a subgroup of participants with elevated baseline postprandial insulin levels.

Effect of Avocado Consumption on Risk Factors of Cardiovascular Diseases: A Systematic Review and Meta-Analysis

High cholesterol levels are a significant risk factor for heart disease, the leading cause of death worldwide. Lowering cholesterol plays a crucial role in maintaining good health. One approach to reducing cholesterol is through dietary modifications, and avocados have been recognized as a potential food choice for this purpose. Avocados are rich in monounsaturated fatty acids (MUFAs), fiber, and plant sterols, which have cholesterol-lowering effects. Incorporating avocados into a low-fat diet can be beneficial. This study design followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and conducted databases in Cochrane, SCOPUS, PubMed, and Web of Science up until May 2023, combining keywords related to avocados and cardiovascular diseases (CVDs). The study focused on randomized clinical trials (RCTs) and excluded observational studies, meta-analyses, surveys, abstracts, and reviews. Seven RCTs were included in the study, all reporting total cholesterol (TC) levels. The findings of the study showed that individuals who followed an avocado diet experienced reduced TC levels compared to those who followed a habitual diet or a low-fat diet. The avocado group exhibited lower TC levels compared to the control group in both the habitual diet and low-fat diet subgroups. When considering high-density lipoprotein (HDL) levels, the control group had higher HDL levels than the avocado group in the habitual diet subgroup, while the avocado group had higher HDL levels than the control group in the low-fat diet subgroup. In both the habitual diet and low-fat diet subgroups, the avocado group had lower levels of low-density lipoprotein (LDL) compared to the control group. The study concluded that incorporating avocados into the diet can be a beneficial dietary strategy for individuals aiming to lower their cholesterol levels and promote heart health. The avocado diet was associated with decreased LDL levels, but it did not significantly impact triglyceride (TG) levels or fasting glucose levels. Systolic blood pressure values showed minimal changes with the avocado diet.

Mexican Ancestral Foods (Theobroma cacao, Opuntia ficus indica, Persea americana and Phaseolus vulgaris) Supplementation on Anthropometric, Lipid and Glycemic Control Variables in Obese Patients: A Systematic Review and Meta-Analysis

Diet containing Mexican ancestral foods such as cocoa, nopal, avocado, and common bean have been individually reported to have beneficial effects on obesity and comorbidities. Methods: A systematic review and meta-analysis on the effect of Mexican ancestral foods on the anthropometric, lipid, and glycemic control variables in obese patients was performed following PRISMA guidelines. Data were analyzed using a random-effects model. Results: We selected 4664 articles from an initial search, of which only fifteen studies satisfied the inclusion criteria. Data for 1670 participants were analyzed: 843 in the intervention group and 827 in the control group. A significant reduction in body mass index (mean difference: −0.80 (−1.31 to −0.30)) (95% confidence interval), p = 0.002, heterogeneity I2 = 92% was showed after the ingestion of cocoa, nopal, avocado, or common bean. The mean difference for body weight was −0.57 (−1.93 to 0.79), waist of circumference: −0.16 (−2.54 to −2.21), total cholesterol: −5.04 (−11.5 to 1.08), triglycerides: −10.11 (−27.87 to 7.64), fasting glucose: −0.81 (−5.81 to 4.19), and insulin: −0.15 (−0.80 to 0.50). Mexican ancestral food supplementation seems to improve anthropometric, lipid, and glycemic control variables in obesity; however, more randomized controlled trials are needed to have further decisive evidence about dosage and method of supplementation and to increase the sample size.