February 16, 2021
Most people are unaware of the calorie content of the beer, wine, or spirits they are imbibing and would support mandatory labels with this information -- but it is unclear if this would dampen excess drinking and reduce obesity, say the authors of a new global review of existing, mainly weak, evidence.
The findings by Eric Robinson, PhD, from the Department of Psychology, University of Liverpool, UK, were recently published in Obesity Reviews.
The work was prompted by a call from the UK government in 2020 for scientific evidence on the topic, because it plans to consider a policy of mandatory calorie-content labels on alcoholic drinks to address the public health issues of excess drinking and obesity.
The review is "based on a very small number of studies with substantial methodological issues (very low evidential value and high level of uncertainty)," the authors caution, and the findings "may change as a result of higher quality studies conducted in real-world settings."
'A Step in the Right Direction'
Nevertheless, "although it's unclear if calorie labels will have a meaningful impact on what people choose to drink," Robinson said in a statement, "making sure drinks have to be clearly labeled is a step in the right direction and may also encourage the alcohol industry to cut calories in drinks."
Timothy S. Naimi, MD, MPH, director of the Canadian Institute for Substance Use Research at the University of Victoria, British Columbia, who was not involved with the research, agrees.
"It doesn't really make sense that they don't provide calorie information just like they would for a can of peas," said Naimi, formerly from Boston University, who was a member of the US Department of Agriculture's 2020 Dietary Guidelines Advisory Committee.
"If we go to the trouble to develop government national drinking guidelines, it's unconscionable that they don't [also] provide standard drink [size] information on the labels," he told Medscape Medical News.
According to Naimi, "most people would be very surprised to know alcohol (or ethanol) has 7 calories per gram -- almost as much energy density as in fat (9 calories/gram)" and more than in protein or carbohydrates (each 4 calories/gram).
In the United States, a standard alcoholic drink is 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz (a typical shot) of 40% (80 proof) spirits.
A standard drink contains about 14 grams of ethanol, which is about 100 calories, and other components in the drink can add more calories.
A Canadian study that Naimi coauthored in 2019 looked at regular alcohol imbibers and found that the average participant consumed 250 calories/day (11% of their total calorie intake) from alcohol, which would be similar in the United States, said Naimi.
"Over the last 15 years or so, people have been drinking more and people have been gaining more weight and there may be a connection," he summarized.
"But the important point," Naimi stressed, is that "people should have the [calorie and standard size] information available to help them make those informed choices [about alcohol consumption], and currently they don't."
UK Considers Mandatory Calorie Labels on Alcoholic Drinks
Heavy drinking of alcohol has consistently been associated with increased risk of liver and cardiovascular disease, and some studies suggest it is also a risk factor for weight gain and obesity, Robinson and colleagues note.
They conducted a rapid systemic review of the literature to identify studies examining 1) consumer knowledge of calorie content of alcoholic drinks, 2) public support for calorie-content labeling of alcoholic drinks, and 3) the effect of such labeling on consumption behavior.
They identified 16 articles about 18 studies that were conducted in Europe, the United States, Australia, and New Zealand.
Eight studies (all with low methodologic quality) examined knowledge of the calorie content of alcoholic drinks. They asked consumers, for example, "How many calories are in a glass of red wine?"
In pooled data, 74% of the consumers did not accurately estimate the caloric content of alcoholic drinks.
Nine studies (six with low methodologic quality, three with moderate quality) examined support for requiring calorie-content labels on alcoholic drinks.
They asked consumers, for example, "Should it be a requirement that nutritional information is displayed on bottles/cans/casks of alcohol?"
In pooled data, 64% of consumers supported calorie-content labeling of alcoholic drinks.
No Evidence That Knowing Calorie Content Would Change Habits
Six diverse, low-to-moderate quality studies investigated whether having information about calorie content would change consumers' planned consumption of alcoholic drinks, and there was no evidence that having this information would change behavior, but these were not real-world studies.
"As far as we are aware, mandatory energy labeling of alcoholic drinks has not been introduced in any of the countries in which included studies were conducted," the researchers note.
They conclude: "Further research is required to determine whether energy labeling of alcoholic drinks is likely to be an effective public health policy."
Robinson has previously received funding from the American Beverage Association and Unilever for projects unrelated to the current research. The other authors and Naimi have reported no relevant financial relationships.