Published in the American Journal of Clinical Nutrition, the randomised crossover study involved the recruitment of 67 volunteers in Spain considered to be at a ‘high risk’ of CVD.
This was due to increased BMI, smoking, diabetes and hypertension, alongside other risk factors; around 50% were taking ACE inhibitors, statins, aspirin and/or hypoglycemic drugs.
After agreeing not to consume alcohol during a baseline period, the subjects then drank 30g per day of alcohol as red wine or gin, or an equivalent amount of phenolics from dealcoholised red wine.
High compliance with the assigned interventions was reported, due to such factors as the return of empty bottles signifying participation, dietary records and assessment of urinary metabolites.
There was also strong evidence that there were no fundamental changes between dosage periods in regard to diet or exercise habits.
The effects of each intervention on a large number of adhesion molecules and chemokines that affect inflammation (and relate to the development of vascular disease) were evaluated.
Both the alcoholic and non-alcoholic red wines had equal amounts of phenolics, and the results showed that both ethanol and non-alcoholic compounds in red wine had potentially protective effects that may reduce the risk of vascular disease.
Chiva-Blanch et al. summed up their results thus: “The phenolic content of red wine may modulate leukocyte adhesion molecules, whereas both ethanol and polyphenols of red wine may modulate soluble inflammatory mediators in patients at high risk of cardiovascular disease.”
One academic reviewer for the International Scientific Forum on Alcohol Research (ISFAR) said: “This…paper goes a way towards answering whether it is alcohol or polyphenols in red wine that confer the health benefits,” while another called for further information on separating the effects of beer, wine and spirits.
“Some spirits like brandy and whisky can have useful antioxidant effects, so distinguishing effects among different types of benefits may be informative,” the second reviewer said.
New mechanistic evidence
The overall ISFAR summary of the paper – collating various comments by international specialists – praised it design for breaking with an observational epidemiological study [of health events or determinant patterns] mould that had one marked drawback.
Such studies, “of necessity, compare people who prefer certain beverages, but not the beverages themselves. While there have been many intervention trials in animals, randomised trials in humans are less common," the team wrote.
It added: “Randomised crossover trials, in which each subject receives all interventions in sequence, can be especially important as they tend to avoid baseline differences among subjects, and can detect effects of different interventions with a smaller number of subjects.”
“Thus, this study provides important new mechanistic evidence that the reduced risk of cardiovascular disease among red wine drinkers observed in most epidemiologic studies may result from a combination of both the alcohol and the polyphenols in the wine.”
Title: ‘Differential effects of polyphenols and alcohol of red wine on the expression of adhesion molecules and inflammatory cytokines related to atherosclerosis: a randomized clinical trial’
Authors: G. Chiva-Blanch, M. Urpi-Sarda, R.Llorach, M.Rotches-Ribalta, M.Guillèn, R.Casas, S.Arranz, P.Valderas-Martinez, O.Portoles, D.Corella, F.Tinahones, R.M. Lamuela-Raventos, C. Andres-Lacueva, R. Estruch
Source: American Journal of Clinical Nutrition (2012) doi: 10.3945/ajcn.111.022889