With commentary by lead study co-author Rachel Golan, RD, PhD, a researcher in public health at Ben-Gurion University of the Negev.
The researchers say it’s the first long-term, real-world look at the effects and safety of moderate, regular alcohol consumption for type 2’s, who are often advised to be wary of beer, wine and cocktailss. Study volunteers followed a conservative eating-and-drinking plan: A maximum of five ounces of red or white wine daily (a control group had mineral water instead), always with dinner. All were asked to also adopt a Mediterranean-style diet with more vegetable oils, vegetables, fish, nuts, whole grains and legumes (like red or black beans) and fewer sweets, trans fats, pasta and potatoes.
Drinks were on the house. Dry red or white wine from the Golan Heights Winery or mineral water from Mey Eden were provided by the research project to each volunteer. Empty bottles were collected and fresh bottles handed out at each check-up.
“This is definitely a cause for modest celebration,” says Rachel Golan, RD, PhD, a researcher in public health at Ben-Gurion and one of the study’s lead authors. “We know that excessive drinking is not recommended for anyone. But here we are talking about one drink a day—and we found that it’s not harmful for people with type 2 diabetes and may be beneficial. The calories added from this glass of wine are not much, but they should be taken into consideration – and the benefits might be much more worthwhile than another slice of bread. We did ask participants to reduce about 100 calories towards the glass of wine.”
The study isn’t an open invitation to an open bar for everyone, Golan adds. It looked at carefully chosen volunteers who were healthy and at low risk for over-indulging and other adverse effects. All were between the ages of 40 and 75 and, at the start of the study, consumed alcohol less than once a week. Their diabetes was well-controlled, they didn’t smoke and had no family history of addiction, heart disease, stroke or, for women, breast cancer. “Only people with controlled diabetes should consider adding a glass of wine to their dinner. Those who have a difficult time sticking with just one drink and women with concerns about breast cancer should probably avoid initiating this custom,” notes Golan.
Wine drinkers were advised to gradually ramp up to five ounces a day (they used measuring cups) and told not to drive after their evening glass. They were also tested for genes that determine how fast their body breaks down alcohol – a lab test that’s not available to the public, Golan said.
The results? On average, participants didn’t gain weight, have wild blood-sugar swings or develop liver-function problems. Among the 73 red wine drinkers, HDLs increased 9.8%—a rise of 3.5 to 4 points that could improve heart health. In some studies, every 1 point rise in HDLS reduced coronary heart disease risk by 2% for men and 3% for women. Levels of apolipoprotein A1 (a major constituent of HDL cholesterol) also increased. And levels of heart-threatening blood fats called triglycerides did not rise. That’s significant, because triglycerides are often high in people with type 2, and alcohol can raise levels even higher.
Fasting blood sugar levels dipped for red and white wine drinkers with a genetic mutation that made their bodies metabolize alcohol slowly, but not for the one in five who were “fast metabolizers” with a genetic quirk that made their bodies break down the alcohol swiftly. Even so, the blood-sugar benefits were small and didn’t affect medication use for the 75% of volunteers taking oral blood-sugar drugs or the 12% using insulin. Fast metabolizers did see blood pressure fall slightly. All three groups lost about three pounds per person. The researchers’ conclusion: “These benefits should be weighed against potential risks when translated into clinical practice.”
“When starting to drink, a person with diabetes type 2 should be aware of any changes in his or her blood sugar and act accordingly. But as we saw from our study, it did not interfere with glycemic control,” Golan adds.
According to Iris Shai, Rd, PhD, Professor of Nutrition and the Epidemiology of Chronic Diseases at Ben-Gurion University and another of the study’s lead authors, wine’s modest benefits likely came from two things: the ethanol in red and white wines and the beneficial polyphenols found in red wine. “The differences found between red and white wine were opposed to our original hypothesis that the beneficial effects of wine are mediated predominantly by the alcohol,” she notes. “But the red wine had 7-fold higher levels of total phenols and 4 to 13-fold higher levels of the specific resveratrol group compounds than the white wine. The genetic interactions suggest that ethanol plays an important role in glucose metabolism, while red wine's effects additionally involve non-alcoholic constituents.”
Red wine polyphenols come from the grape skins that stay in the vat or tank during fermentation, explains endocrinologist R. Paul Robertson, MD, Principal Scientist of the Pacific Northwest Diabetes Research Institute and a professor of medicine and pharmacology at the University of Washington in Seattle. “It’s not just the ethanol but also the antioxidant polyphenols that are beneficial,” he says. “That’s the whole point of the French Paradox. The antioxidants in red wine can help protect against heart disease.”
While many medical centers discourage alcohol for people with diabetes, according to the American Diabetes Association “most people with diabetes can have a moderate amount.” The ADA recommends enjoying it the way people in the study did – with a meal and in limited quantities (1 drink a day for women, up to two for men). Check your blood sugar before and for up to 24 hours afterward to see how alcohol is affecting you; it can cause low blood sugar.
Dr. Robertson adds that stern cautions against alcohol use in diabetes “are more Puritanical than rational. There’s nothing in the research literature to suggest that wine, in moderation, is bad for you — particularly for people with type 2 diabetes who are already at higher risk for heart disease.” In a recent review of the research on red wine and health for people with diabetes, published in 2014 in the journal Diabetes, he notes that wine is associated with relaxation, reflection, celebration, conviviality, toasting, and a certain amount of dry humor” and that “It may be that one significant mechanism of wine’s beneficial effects is …relaxing with good friends during a savory meal with a great cabernet.”