Nearly every study over the past three decades that has found health benefits in wine consumption has added a crucial caveat: Drink in moderation. Most health experts define moderation as roughly two glasses per day for a man and one for a woman.
But how big is your glass?
A new study published in the BMJ (formerly the British Medical Journal) found that the average wineglass capacity in England has been steadily growing over the past 300 years. Researchers from the University of Cambridge collected data from five sources—the Ashmolean Museum of Art and Archaeology at Oxford University, the Royal Household of the United Kingdom (where a new set of glassware is commissioned for each monarch), English glassware company Dartington Crystal, John Lewis department store and eBay—to record the capacities of more than 400 wineglasses that were available or sold in England between 1700 and 2017.
According to the study, wineglass capacity increased from an average of 66 milliliters (roughly 2.2 ounces) in the 1700s to 230 milliliters (7.8 ounces) in the early 1990s. In the past 25 years, the growth has been even more dramatic: There was an almost doubling in size, with averages skyrocketing to 450 milliliters (15.2 ounces, or more than a half-bottle of wine) in 2017.
What does this have to do with your health? When scientific studies discuss a glass of wine, they typically define that as 5 ounces. That’s also the FDA’s definition of one serving. According to the study's authors, growing glasses might be related to higher wine consumption rates over the years.
"The amount of alcohol people drink, particularly wine, has increased sharply since the 1960s," the study's text states, citing a 2009 memorandum on the U.K. Parliament website. "Along with lower prices, increased availability and marketing, larger wineglasses may have contributed to this rise through several potentially co-occurring mechanisms."
This team of researchers has looked at wine glasses before. In 2015, they compared a restaurant's wine sales when it served the same portion of wine in small, medium and larger glasses. In that study, when using larger glasses, the restaurant saw a nearly 10 percent increase in wine sales by volume. (When they replicated the study in two different bars, they found similar results in one trial but the other was inconclusive.)
"From a public-health perspective, which was the main motivation for studying wineglasses, the most important question raised by our findings concerns the potential … to reduce excessive consumption of wine," Dr. Theresa Marteau, director of the Behaviour and Health Research Unit at the University of Cambridge and a researcher involved in the studies, told Wine Spectator via email.
While moderate drinking may afford wine lovers myriad health benefits, drinking too much can lead to just as many problems. And even if you're not making a conscious decision to order another vino (a la the 2015 restaurant study), bigger glasses may still be causing you to drink more than you think. A 2013 study published in the journal Substance Use & Misuse tested whether glass size (among other factors) affected the amount of wine people poured in their glasses. They found that the average pour into a wide wineglass was 11.9 percent higher than pours into a standard one.
There are plenty of possible explanations for why glasses have increased in size, and it's likely due to a combination of factors, such as changes in fashion and trends, the cost of glass—which has dropped significantly since the 1700s—and the advancement of manufacturing technologies.
We also now know that larger bowls allow drinkers to better appreciate wine's aromas—information the British glassmakers of the 18th century probably weren't privy to.
“The increase in size [over the years] comes from the research of winemakers and glassware experts discovering certain grape varieties require more room in the bowl to show their full expression," said Maximilian Riedel, CEO of Riedel glassware company, via email. "I can’t speak [for] all wine consumers, but I don’t believe a bigger bowl size necessarily correlates with an increased wine consumption—though it certainly increases the pleasure!"
But what tends to happen when humans have something they really enjoy? They crave more. But that doesn’t mean it’s good for health or for the enjoyment of the wine.
"Pouring a larger volume of a wine into a larger glass does not enhance any characteristics of the wine, which is what these shapes were designed for," Riedel advised, also adding: “Wine requires breathing room to express aromas, one of the most important components in experiencing any wine."
So next time you're faced with a larger-than-life glass, remember that you don't need to fill it to the brim. In fact, keeping it to 5 ounces will likely provide a better drinking experience. And if it takes a measuring cup to make sure you're getting your ideal amount of wine, then so be it.