Even Diet Sodas Are Tied to an Increased Risk of Early Death

A person pouring soda into glasses.
(Image credit: Shutterstock)

Consuming too many soft drinks — even diet drinks — may increase your risk of early death, a new study suggests.

The study, which included data from nearly half a million people in Europe, is the largest of its kind, the authors said. People who consumed two or more glasses of soda per day — either regular or diet — were 17% more likely to die during the nearly two-decade study, compared with people who consumed less than one glass of soda per month, the study found.

The findings held even after the researchers took into account factors that could affect people's risk of premature death and disease, such as smoking, alcohol use, body mass index (BMI), physical activity, calorie intake and consumption of fruits, vegetables and processed meats. 

Related: 11 Ways Processed Food Is Different from Real Food

Still, the study only found an association and cannot prove that soda consumption actually causes early death.

But the results, published Sept. 3 in the journal JAMA Internal Medicine, support "ongoing public health campaigns aimed at reducing the consumption of soft drinks," according to the study authors, who are from the International Agency for Research on Cancer, a part of the World Health Organization.

Related: Is diet coke bad for you?

The study adds to a growing body of research linking soda consumption with an increased risk of chronic disease and early death. In March, a different group of researchers published a study in the journal Circulation that found a link between the consumption of sugar-sweetened beverages and an increased risk of early death among U.S. men and women. That study also found that consuming large amounts of diet beverages was linked with an increased risk of early death among women.

In the new study, the researchers analyzed information from about 450,000 people living in 10 European countries who did not have cancer, heart disease, stroke or diabetes at the start of the study. Participants reported how often they consumed diet or regular soft drinks. They were followed for 16 years, on average, and during that period, about 41,700 participants died.

Among those who reported consuming at least two soft drinks a day, 11% died during the study period, compared with 9% of those who reported consuming fewer than one soft drink per month.

Interestingly, people who frequently consumed diet sodas were more likely to die from cardiovascular diseases, such as heart disease; while people who frequently consumed sugar-sweetened sodas were more likely to die from digestive diseases, such as diverticulitis or liver diseases, compared with those who rarely consumed soft drinks.

It's unclear why diet sodas in particular were linked to an increased risk of death from cardiovascular diseases. It may be that this finding is actually due to "reverse causation" — in other words, people who were already at risk for heart disease at the start of the study switched to drinking diet sodas before they filled out the researchers' survey. But the researchers tried to account for this by excluding deaths that occurred early on in the study's follow-up period, and they still found a link between diet soda consumption and death from cardiovascular diseases.

There may be a biological explanation; for example, studies in animals suggest that frequent consumption of artificial sweeteners may lead to problems with the way the body handles real sugar. But much more research is needed to determine whether this is true in people, or whether there are other harmful effects from the long-term consumption of artificial sweeteners, the authors said.

It's also uncertain why regular soda consumption was linked to an increased risk of death from digestive diseases. It's possible that high blood sugar levels may alter the gut lining and increase the risk of gut infections, which in turn increases the risk of certain digestive diseases, the authors said. But again, more research is needed to investigate this.

The authors also note that the study assessed soft drink consumption only at a single point in time, and so the researchers could not account for changes in soft drink consumption during the follow-up period.

 Originally published on Live Science. 

Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.