Hold up, diet soda drinkers. Regular consumption of soft drinks - both sugar-sweetened and artificially sweetened - was associated with a greater risk of all causes of death, according to new research published this week in the Journal of the American Medical Association.
Participants who drank two or more glasses of soft drinks per day had a higher risk of mortality than those who consumed less than one glass per month.
The study, one of the largest of its kind, tracked 451,743 men and women from ten countries in Europe. It found that consumption of two or more glasses of artificially sweetened soft drinks a day was positively associated with deaths from circulatory diseases. For sugar-sweetened soft drinks, one or more glasses a day were associated with deaths from digestive diseases, including diseases of the liver, appendix, pancreas and intestines.
The researchers recruited people from Denmark, France, Germany, Greece, Italy, the Netherlands, Norway, Spain, Sweden and the United Kingdom between 1992 and 2000, surveying them on their food and drink consumption. Participants were excluded if they reported incidents of cancer, heart disease, stroke or diabetes. Mean age was 50.8 and participants were 71.1% female.
Similar results have been shown in several recent studies but the researchers cautioned that elevated soft drink consumption may be a marker for an overall unhealthy lifestyle.
"In our study, high soft drinks consumers had a higher body mass index (BMI) and were also more likely to be current tobacco smokers," said the study's chief researcher, Neil Murphy of the International Agency for Research on Cancer. "We made statistical adjustments in our analyses for BMI, smoking habits and other mortality risk factors which may have biased our results, and the positive associations remained."
The researchers saw similar associations in smokers and nonsmokers, as well as in lean and obese participants, which indicates that the soft drink and mortality association is not strongly influenced by smoking habits and BMI.
"The results of this study are significant," said Sarah Reinhardt, lead food systems and health analyst for the Union of Concerned Scientists. "It reinforces a fact that won't surprise anyone in the nutrition field: Processed foods loaded with artificial ingredients will never be the magic bullet to better health, no matter how low they are in sugar. Our bodies are smarter than that."
While advocacy groups like the Center for Science in the Public Interest are broadly appreciative of studies exploring the link between added sugars and human health, they caution that the results could be a "reverse causation" effect, where diet soda drinkers as a population have other common qualities that could indicate a different explanation for the results.
"This new European study is somewhat inconsistent with earlier findings," said Bonnie Liebman, CSPI's director of nutrition. "In the new study, the risk of dying of any cause was more strongly linked to people who drank more diet drinks than to people who drank more sugary drinks."
Murphy said that he cannot rule out the possibility that the artificially sweetened positive associations were influenced by unhealthy individuals switching to artificially sweetened soft drinks.
"We recognize that a possible explanation for the positive associations found for artificially sweetened soft drinks is that participants who were already at greater health risk (those who were overweight or obese; those with prediabetes) may have switched to artificially sweetened soft drinks to manage their calorie and sugar intake."
The good news? Researchers found no link between soft drink consumption and overall cancer death or deaths from Alzheimer's disease.
While the 50 international researchers who conducted the study advanced no theories about the relationships observed, they encourage public health campaigns aimed at limiting the consumption of soft drinks.
According to the American Heart Association, sweetened drinks are the biggest source of added sugar in our diet. In the United States, the percentage of obese children and adolescents has more than tripled since the 1970s, according to the Centers for Disease Control and Prevention. About 40% of adults are obese, according to the American Medical Association.
In the U.S., Berkeley, San Francisco, Oakland and Albany, California; Philadelphia; Boulder, Colorado; Portland, Oregon; and Cook County, Illinois have all moved to impose soda taxes, but more widespread efforts have been met with resistance from the soda lobby. Even so, recent studies show that people are drinking less sugary drinks, opting instead for healthier choices.
Seth Goldman, chief executive of Honest Tea, which is owned by Coca-Cola, said the study should prod big soda companies to introduce alternative beverages.
“It’s all the more imperative to successfully commercialize lower-sugar and less sweet beverages,” he said. “There’s a recognition that the consumer is evolving too. If [soda companies] don’t change, they’re going to miss that evolving consumer. We’re seeing shifts that are unlikely to reverse themselves.”