Daily intake of a whole grape extract may improve antioxidant levels, and improve cholesterol levels, says the first North American study to report such measures.
Scientists from KGK Synergize Inc report that daily supplements with a whole grape extract from Ethical Naturals, Inc. for six weeks were associated with significantly increased HDL-cholesterol levels, compared to placebo.
In addition, results published in the Journal of Functional Foods indicated that levels of 8-isoprostane (a marker of oxidative stress) and oxidized LDL (a risk factor for cardiovascular disease) decreased in people with pre-hypertension, overweight, and/or pre-diabetes.
“These results are of clinical significance in this population of subjects as the role of HDL-C in reverse cholesterol transport is well documented,” wrote the researchers, “and is believed to be cardioprotective, with each 1 mg/dL increase in HDL-C being associated with a 2–4% reduction in the risk of coronary heart disease.
“It is also known that raising HDL-C concentration reduces cardiovascular disease risk independent of LDL-C lowering.”
The research also found that the whole grape extract group experienced improvements in the ratio of total cholesterol to HDL cholesterol, which has been reported to be the most specific lipid risk factor for cardiovascular disease (CVD).
The results were welcomed by Cal Bewicke, President of Ethical Naturals, which manufacturers the grape extract used in the study through a patented process and marketed under the brand name VinCare. The ingredient is used in supplements, and is also GRAS affirmed for beverage use.
“Our team put a lot of work into the development, patenting and GRAS affirmation of this ingredient (VinCare),” said Bewicke, “so the results of this study are very gratifying to us. The report provides specific, dose-related information for the use of a grape extract that supports cardiovascular health and antioxidant activity. This is something of a breakthrough, and does open the door for a new range of products in this important area of health support.”
The researchers recruited 24 pre-hypertensive, overweight, and/or pre-diabetic subjects to participate in their randomized, double-blind, placebo-controlled, pilot study. Participants were randomly assigned to receive either placebo or 350 mg per day of the whole grape extract, providing 60-70% proathocyanidins, consisting of flavan-3-ol units (catechin, epicatechin and epicatechin-3-O-gallate).
Results showed that participants in the whole grape extract group had significantly lower levels of the enzyme superoxide dismutase (SOD) and lower ratios of total cholesterol to HDL-C ratios, compared to placebo.
“Grape seed polyphenols such as gallic acid, catechin and epicatechin have been reported to inhibit pancreatic cholesterol esterase, bind to bile acids, and reduce the solubility of cholesterol in micelles,” wrote the researchers, led by Malkanthi Evans.
“Since the principal steps in cholesterol absorption are emulsification, hydrolysis of the ester bond by pancreatic esterase, micellar solubilization and absorption in the proximal jejunum, it is possible to suggest that grape seed polyphenols affect the absorption of dietary cholesterol.”
In addition, HDL-cholesterol levels were significantly increased compared to placebo.
Evans and co-workers also reported that 8-isoprostane levels decreased by 5% in the whole grape extract, compared to a 50% increase in the placebo group.
“In spite of a small sample size, high individual variation and short study duration, a significant increase in HDL-C and a significant decrease in total cholesterol/HDL-C ratio were seen in subjects supplemented with [whole grape extract] compared to placebo,” they wrote. “Though not significant several important positive trends were found in oxLDL, 8-OHdG and 8-isoprostane.
“Although there was an increase in 8-OHdG in both groups, the increase observed in subjects on placebo was twice as much as those on [whole grape extract]. The results seen in subjects on the placebo demonstrate the movement of parameters associated with oxidative stress in hypertensive, pre-diabetic, and/or overweight/obese subjects not given an intervention.”
Source: Journal of Functional Foods
Published online ahead of print, doi: 10.1016/j.jff.2013.12.017
“A randomized, double-blind, placebo-controlled, pilot study to evaluate the effect of whole grape extract on antioxidant status and lipid profile”
Authors: M. Evans, D. Wilson, N. Guthrie