Effect of fruit and vegetable concentrates on endothelial function in metabolic syndrome: A randomized controlled trial

Ali A, Yazaki Y, Njike VY, Ma Y, Katz DL; Jun. 2011


The primary goal of the study was to determine whether taking two different formulations of a commercially available encapsulated juice powder concentrate could improve endothelial function — a risk factor for type 2 diabetes and cardiovascular disease - in people with metabolic syndrome compared to placebo.  


In this randomized, double-blind, placebo-controlled crossover study, 64 adults with metabolic syndrome were assigned to 1 of 3 groups: Group 1 took an encapsulated fruit and vegetable juice powder concentrate (FV; Juice Plus+®), group 2 took an encapsulated fruit, vegetable and berry juice powder concentrate (FVB; Juice Plus+®) and group 3 took placebo for 8 weeks.  

Following completion of their assigned 8-week sequence, all groups underwent an 8-week washout period and were then switched to a different 8-week sequence. After completing the second 8-week sequence, all groups underwent another 8-week washout period and were switched to the last 8-week sequence. As a result of the crossover design, all groups cycled through all treatment arms.  

Participants’ endothelial function was assessed at 6 different time points (at baseline, at completion of each 8-week treatment sequence, and following two washout periods) using flow-mediated dilation (FMD) of the brachial artery 2 hours after consuming a 75-gram load of glucose, which was intended to induce endothelial dysfunction.  

Researchers also assessed acute (single dose) effects on endothelial function and plasma glucose 2 hours after supplements were taken concurrently with a 75-gram glucose challenge.  

Other secondary outcome measures included plasma glucose, serum insulin, serum lipids and body weight.  


Supplementation did not significantly affect endothelial function or any other metabolic factor in volunteers taking either formulation for eight weeks, though there was a trend toward significant improvement in endothelial function among the group taking the single dose of the FVB. The glucose load did not have the expected deleterious effect on participants’ endothelial function; this may be why it was hard to detect improvement following supplementation.  


“Encapsulated fruit and vegetable concentrates did not alter insulin or glucose measures. Acute endothelial dysfunction was not observed with glucose loading, mitigating against observable treatment effects. Further study with more overt impairment of endothelial function is warranted.”

PubMed link:


PDF summary:
View PDF