Red wine polyphenols show blood sugar benefits: RCT data
A daily glass of red wine or dealcoholized red wine for four weeks was associated with a significant improvement in glucose metabolism, as measured by insulin resistance, according to findings published in Clinical Nutrition.
“In our study both red wine and dealcoholized red wine improved insulin sensitivity which, together with prior findings, suggests that both ethanol and polyphenols are responsible for this beneficial effect,” wrote researchers from the University of Barcelona and the University of Valencia in Spain.
Red wine and heart health
The heart health benefits of red wine led to the coining of the phrase ‘the French Paradox' in 1992 by Dr Serge Renaud from Bordeaux University to describe the low incidence of heart disease and obesity among the French, despite their relatively high-fat diet and levels of wine consumption.
The focus of the French Paradox then shifted towards resveratrol, a powerful polyphenol and anti-fungal chemical, as being the bioactive compound in grapes and red wine.
The subject has been debated extensively, and the new study contributes to our understanding of the subject.
Other studies with only resveratrol have reported anti-cancer effects, anti-inflammatory effects, cardiovascular benefits, anti-diabetes potential, energy endurance enhancement, and protection against Alzheimer’s.
Study details
For the new study, the Spain-based researchers recruited 67 men with a high cardiovascular risk and randomly assigned them to consume red wine (30g alcohol per day), dealcoholized red wine, and gin (30g alcohol/d) for four weeks.
Results showed that both forms of wine were associated with decreases in insulin resistance of between 22 and 30%, compared to values at the start of the study, and by between 14 and 22% compared to the gin group.
In contrast, both of the alcohol interventions (red wine and gin) improved HDL cholesterol levels, compared to the dealcoholized red wine group, indicating that these benefits were related to alcohol, and not the polyphenol content.
"While ethanol itself exerts a protective effect on the lipid profile, the non-alcoholic fraction of red wine (mainly polyphenols) has a beneficial effect on insulin resistance and red wine appears to decrease lipoprotein(a) plasma concentrations,” wrote the researchers.
“These findings suggest that red wine has greater protective effects than other alcoholic beverages on cardiovascular risk,” they concluded.
Source: Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.clnu.2012.08.022
“Effects of red wine polyphenols and alcohol on glucose metabolism and the lipid profile: a randomized clinical trial”
Authors: G. Chiva-Blanch, M. Urpi-Sarda, E. Ros, P. Valderas-Martinez, R. Casas, S. Arranz, M. Guillén, R.M. Lamuela-Raventos, R. Llorach, C. Andres-Lacueva, R. Estruch
