Men drink more alcohol than women. It's a long-standing, global truth. But in the U.S., that gender gap is shrinking.
This according to a 2015 study out of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), a division of the U.S. National Institutes of Health. When researchers examined data from the National Survey on Drug Use and Health for 2002 through 2012, they found that women's and men's drinking habits are looking increasingly more alike.
"For almost every single variable we examined, including current alcohol use and binge drinking, females and males are more similar now than a decade ago," says lead author Dr. Aaron White, NIAAA senior scientific adviser to the director. "In no case were the changes in alcohol use particularly large, but to see so many changes across only a decade is quite surprising," he writes in an email.
In some areas, women were simply drinking more. For example, among those ages 45-64, the number of drinks per sitting increased 11 percent between 2002 and 2012. In the 26-34 age group, women reporting at least one binge-drinking episode in the previous month increased 5.1 percent.
The NIAAA defines binge drinking as four or more drinks in a sitting for women and five or more for men. (A "drink" is 5 ounces of wine, 1.5 ounces of 80-proof spirits, like vodka, or 12 ounces of beer.) The agency considers low-risk drinking to be up to seven drinks per week for women and up to 14 for men, with no bingeing on any day.
While women are drinking more than they used to, that's not the only factor in the shrinking gap. The discrepancy between women and men in "current drinking," defined as having had a drink in the past 30 days, narrowed 4.7 percent in the studied decade — but women only saw a 3.4 percent increase (from 44.9 percent to 48.3 percent). While women were drinking more, men were drinking less: The percentage of males currently drinking fell 1.3 percent (from 57.4 percent to 56.1 percent).
The study authors aren't sure what's driving the increase in women's drinking (or the decrease in men's, for that matter). White notes that cultures with smaller gender gaps in alcohol use tend to be ones with greater gender equality.
"It is possible that the relatively small changes in alcohol use during the last decade are tied to progress toward gender equality, but it's just too early to tell," says White.
Dr. Katherine M. Keyes, assistant professor of epidemiology at the Columbia University Mailman School of Public Health, shares that uncertainty, citing limited data.
But, Keyes says via email, "The evidence we do have points to a loosening of social norms around drinking for women, as well as increased entry to the labor market into positions with more social capital as well as the delay of marriage and children.
Overconsumption of alcohol, regardless of gender, has serious downsides. It can negatively affect relationships and employment. It can cause adverse reactions in people taking medications and increases the likelihood of driving under the influence and being the victim of sexual assault. Research links heavy drinking with depression, stroke, cancer, stomach bleeding, liver disease, brain damage and sleep disorders.
For women, though, the risks are often greater.
"In addition to reproductive consequences such as fetal alcohol syndrome for offspring, women have increased rates of chronic disease and mortality at the same level of consumption as men," says Keyes.
This is partly due to the lower volume of alcohol-diluting water in women's bodies, which leaves their organs exposed to more alcohol for a longer period. Women are more likely than men to develop alcohol-related liver disease, heart disease, cancers and brain damage, and alcohol-related brain damage appears to progress faster in women.
According to the study authors, women drinkers also face a higher risk of sexual assault.
"It has become quite clear that alcohol use is an important women's health issue," says White.
And American women aren't the only ones drinking more. According to White, researchers have found similar patterns in New Zealand and Finland. Keyes adds Sweden, Denmark, the United Kingdom and South Korea to that list.
Whatever is driving the change, Keyes thinks the important message is that effective treatment is available.
"Women face greater stigma for entering treatment than men," she says, which often causes them to put off seeking help. Keyes stresses, "Women who want to reduce their drinking should be encouraged to talk to a physician or other health professional."
"If these upward trends continue," Keyes notes, "treatments may need to be tailored to meet the needs of women more specifically."