The findings by Professor Iris Shai, Ben-Gurion University of the Negev and Professor Meir Stampfer, Harvard School of Public Health, was unveiled at this year’s European Congress on Obesity in Prague.
Recommendations for moderate alcohol consumption remain controversial, especially in the management of type 2 diabetes (T2D) but by adding to the relative lack of long-term randomised controlled trials (RCTs) in this area, the authors hope to expand understanding of its impact.
Prof Shai said: "This first long-term large scale alcohol trial suggests that ini¬tiating moderate wine intake, especially red-wine, among well-controlled T2D, and as part of healthy diet, is apparently safe and decreases car¬diometabolic risk. While the genetic interaction supports specific causal roles for ethanol, the red-wine's superiority suggests that non-alcoholic constituents of red wine could be having a positive impact.
"The differences found between red and white wine were opposed to our original hypothesis that the beneficial effects of wine on lipids are mediated predominantly by the alcohol. Yet, the differential effects in patients with the genetic variation for alcohol metabolism on their blood sugar control support a causal role of alcohol on blood sugar control. Thus, genetic profiling may assist in identifying patients with type 2 diabetes in whom moderate wine consumption may induce greater clinical benefit."
The authors did a 2-year RCT [the two-year CArdiovaSCulAr Diabetes & Ethanol (CASCADE) trial] among 224 controlled diabetes patents, who had been abstaining from alcohol, following a previous 3-month alcohol pilot trial.
All groups followed a non-calorie restricted Mediterranean diet. The trial was performed in Israel, at Ben-Gurion University, by Professor Shai’s research group which is focused on performing long-term dietary randomised controlled trials.
Most patients (87%) completed the two-year study. The results showed that red wine was found to be superior in improving metabolic profiles, by modestly increasing good (HDL) cholesterol and apolipoprotein A1 (one of the major constituents of HDL cholesterol), while decreasing the ratio between total cholesterol and HDL cholesterol.
Around one in five of the participants were found to be fast alcohol metabolisers, identified through genetic tests showing they had a particular variation related to alcohol metabolism. Slow alcohol metabolisers who drank wine were found to have better blood sugar control than fast alcohol metabolisers who drank wine.
Wine of either type did not affect medication usage, blood pressure, or liver function tests. Although both wine groups modestly improved glucose metabolism, overall, improvements in the metabolic profiles were mainly attributed to red-wine.
Dr Alasdair Rankin, Diabetes UK Director of Research, added: “The evidence that red wine can help improve management of diabetes is extremely weak and any potential health benefits from drinking alcohol would be outweighed by the well-known side effects, such as weight gain.
"What we do know is that a lot of us already drink more alcohol than is good for us, so most people with Type 2 diabetes should in fact be actively trying to reduce their alcohol intake, not increase it. Currently, the best way to manage Type 2 diabetes is by taking prescribed medications and maintaining a healthy weight through regular physical activity and a healthy balanced diet that is low in saturated fat, sugar and salt."