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

Abstract

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.

Keywords: autophagy; avocado; cardiovascular risk factors; glucose; insulin; mannoheptulose.

Figure 1

Study consort. AUC, area under the curve; SD, standard deviation.

Figure 2

Plasma glucose (A) and insulin (B) responses over 2.5 h after the oral glucose tolerance test before and after the 12-wk avocado extract (AvX, n = 25) or placebo (n = 26) intervention in adults with obesity. Data are means ± SEMs. Between-group analysis for each variable was performed using ANCOVA, adjusted for baseline values and sex.

Figure 3

Difference in percentage of reduction in insulin AUC (cumulative insulin levels during oral glucose tolerance test) in a subgroup of participants with insulin AUC above medium at baseline.