Latest scientific news 27 October 2015

Moderate wine consumption may decrease cardiovascular risk among type 2 diabetics

The current CASCADEThe CASCADE study (CArdiovaSCulAr D study is the first large, long-term randomized controlled trial with wine. The results suggest a better lipid and glucose control when alcohol-abstaining type 2 diabetics initiated moderate wine consumption combined with a healthy diet and had no significant harmful effects. Genetic tests might help identify diabetic patients who potentially can benefit from moderate drinking.

Prospective, epidemiological studies consistently found for decades that the risk of developing type 2 diabetes mellitus is reduced among moderate drinkers in comparison with non-drinkers, with previous meta-analyses suggesting that moderate drinkers may have about 30% lower risk than that of abstainers. Among healthy individuals, moderate intake of alcoholic beverages has been linked to lower rates of cardiovascular disease and death. It is not clear whether patients with type 2 diabetes mellitus (T2DM) would have similar health benefits, if they drink wine /alcoholic beverages or whether this behavior would be harmful to their health. There have been few clinical trials where alcoholic beverages or wine were administered to diabetics and most have been for a relatively short period of time. The objective of the current study was to examine the possible health benefits and harms when T2DM patients would start drinking wine moderately, its effect on blood pressure and whether the type of wine matters.

In this first, long-term randomized controlled (CASCADEThe CASCADE study (CArdiovaSCulAr D= CArdiovaSCulAr Diabetes & Ethanol) study, 224 diabetic patients – who were abstainers or very light drinkers before enrolling in the study – were randomly assigned to drink 150 ml of red wine, white wine or mineral water with their dinner for 2 years and all groups followed  a Mediterranean diet without any calorie restriction. Various lipid parameters (HDL cholesterol, apolipoprotein a1 and the total cholesterol-HDL cholesterol ratio), blood pressure and the glucose control were determined at the beginning of the study and at 6 and 24 months.

The results showed that among patients with well-controlled T2DM and a low risk for alcohol abuse, initiating moderate wine consumption in the context of a healthy diet favorably affected many cardiometabolic factors. Red wine in particular improved the lipid parameters (HDL cholesterol and apolipoprotein a), which indicates a possible synergy of moderate alcohol intake with specific non-alcoholic wine ingredients (polyphenols). Consuming similar amounts of white wine was also beneficial and specifically improved measures of glycemic control (1).

In addition, in 203 participants, effects according to the genetic factors determining alcohol dehydrogenase (ADH) were evaluated. Ethanol is oxidized to acetaldehyde in the liver via the enzyme ADH. A common genetic variant of ADH greatly enhances the enzyme’s reaction rate. In both wine groups (red and white), patients who were “slow alcohol metabolizers” (according to genetic tests) showed more improvements in glucose control tests than “fast alcohol metabolizers”. This indicates that ethanol may play a role in the glycemic effects of the wine intervention.

The genetic ADH variants may help identify patients with T2DM for whom moderate wine consumption may be clinically beneficial.

While there is consistent evidence that heavy intake of alcoholic beverages is positively associated with hypertension, the association with moderate intake and blood pressure (BP) remains unclear. To examine this relation, a sub-group of the study population (54 patients) was randomized to consume either 150 ml of red wine or water during dinner for 6 months. All participants further received counseling for a Mediterranean diet, without calorie restriction. The blood pressure was monitored for 24 h at the beginning and after 6 months. The fast and slow metabolizers of alcohol were also determined. The results showed that the daily consumption of red wine did not affect the 24h BP. Compared to water, wine did not increase or decrease blood pressure. Furthermore, the researchers found a different association of wine and BP between fast and slow ethanol metabolizers. Diabetic patients who were fast ethanol metabolizers, benefited the most from the wine-induced blood pressure lowering effect which suggests a mediatory role for ethanol metabolites and potentially explains inconsistent reports/study results about blood pressure effects with moderate alcohol intake (2).

(1)      Gepner Y et al, Effects of initiating moderate alcohol intake on cardiometabolic risk in adults with type 2 diabetes, 2015, Ann Intern Med, p 569-579

For more information about this article, read the scientific abstract here.

(2)      Gepner Y. et al, Differential effects of initiating moderate red wine consumption on 24-h blood pressure by alcohol dehydrogenase genotypes: randomized trial in type 2 diabetes

For more information about this article, read the scientific abstract here.