The study, published in Atherosclerosis , presents evidence to suggest that the athero-protective effect of the açaí juice is in part due to reduced break down of lipids (lipid peroxidation) – which may be due to increasing the levels and activity of two antioxidant enzymes.
The research, supported by açaí producer and distributor MonaVie LLC, also supports the possibility that açaí juice may exert protective effects against the development of atherosclerosis by inhibiting pro-inflammatory compounds called cytokines, through regulating inflammatory mediators.
“We provide direct experimental evidence showing that a diet containing an açaí juice at the dose of 5 percent developed significantly less atherosclerotic lesions,” said the researchers, led by Dr Xianli Wu from the University of Arkansas for Medical Sciences, USA.
The authors said the study “provides the first reported indication that açaí juice protects against atherosclerosis,” adding that the results “clearly indicate that açaí juice significantly reduced lipid peroxidation.”
“Reducing lipid peroxidation through boosting antioxidant enzymes and inhibiting pro-inflammatory cytokine production are proposed as major underlying mechanisms for the athero-protective effects of the açaí juice tested in these experimental in vivo models,” explained the researchers.
Dr. Wu and his colleagues explained that cardiovascular disease is the leading cause of death, not only in the United States “but also in most of the industrialized world.”
“It has long been recognized that a diet rich in fruits and vegetables may have beneficial effects on cardiovascular diseases, largely attributed to their antioxidant and anti-inflammatory properties,” they added.
However, the researchers noted that in vivo experimental evidence to support the consumption of specific fruits and vegetables in reducing the risk of cardiovascular disease based on plausible underlying mechanisms “remain scarce.”
Açaí (Euterpe oleracea) fruit pulp has received much attention because of its high antioxidant capacity and potential anti-inflammatory effects, leading to claims in recent years that the fruit is a ‘superfruit’.
Recent research in rats has suggested diet supplementation with açaí pulp improves biomarkers of oxidative stress, resulting in a cholesterol reducing effect.
“This suggested that consumption of açaí could improve antioxidant status and provide athero-protective effects in an animal model of hypercholesterolemia,” said Wu and his colleagues.
Açaí pulp and juice has also been shown to possess several anti-inflammatory effects, including inhibition of nitric oxide production via a reduction in inducible nitric oxide synthase (iNOS) expression.
The new study investigated the athero-protective effects of a freeze-dried and frozen açaí pulp juice mixture in a mouse model.
The açaí juice blend (provided by MonaVie) contained freeze-dried and frozen açaí (Euterpe oleracea Mart.) pulp as the predominant ingredient.
Markers of oxidative stress were found to be significantly lower in the serum and liver of açaí juice fed animals.
Results from analysis of 17 genes related to oxidation/antioxidant enzymes also showed that expression of two antioxidant enzyme genes glutathione peroxidase (GPX) and glutathione reductase (GSR) – considered important antioxidant enzymes in vascular systems – were significantly up-regulated in the aorta of açaí juice fed mice.
The activities of GSR in serum and liver and GPX in serum were also reported to increase in açaí juice fed mice.
“Hence, these two antioxidant enzymes may act synergistically to reduce lipid peroxidation,” suggested Wu and his co-workers.
Serum antioxidant enzyme PON1 (associated with HDL and implicated in the prevention of LDL lipid peroxidation) was found to be also elevated in açaí juice fed mice.
In further experiments, mice fed açaí juice for 5 weeks were reported to have significantly lower serum levels of the pro-inflammatory cytokines IL-6 and TNF-α.
“Not only did açaí juice reduce basal levels of these two pro-inflammatory cytokines, it also increased the resistance of secretion of these two cytokines by macrophages in response to inflammatory stimuli such as LPS,” said the authors.
The authors of the research are from the USDA Arkansas Children's Nutrition Center, the Department of Physiology and Biophysics, and the Department of Immunology, at University of Arkansas for Medical Sciences and AIBMR Life Science Inc.