One week after a state Supreme Court judge quashed Mayor Michael Bloomberg’s plan to ban the sale of large sugary drinks in New York City, a team of Harvard Researchers unveiled the first-ever accounting of the health toll sodas, sports drinks and sugar-laden juices take on the global population. Their conclusion: They kill 184,000 people annually. “I hope that seeing the actual number of deaths will give policy makers who are interested in making a change in this area some ammunition,” says lead author Gitanjali Singh, PhD, a research fellow at the Harvard School of Public Health in Boston. She presented the study at an American Heart Association conference in New Orleans in March. We asked her how she did it and what its implications are.
Why did you do this study?
Gitanjali Singh: We know that sugary beverages are linked to obesity, and we know a large number of deaths worldwide are caused by obesity-related diseases such as diabetes, cardiovascular disease and certain cancers. We wanted to figure out how many deaths from obesity-related diseases are caused by drinking sugary beverages.
How did you do it?
GS: It was an extensive, five-year data collection process. We obtained data on sugary beverage consumption from about 114 surveys (from government health organizations, nongovernmental organizations and published literature) representing about 720,000 people from 54 countries and about 62 percent of the world’s population. Then we looked at the relationship between sugary beverage consumption and obesity, and obesity and cardiovascular disease and cancer using large cohort studies involving hundreds of thousands of participants.
We used cause-specific mortality data from the World Health Organization. We then used a well-established risk assessment framework to quantify the number of deaths.
How many sugar-laden beverages do people drink?
GS: There is a large global variation. Intake ranged from less than one serving (8 ounces) per day in Chinese women older than 65 to more than five servings per day in Cuban men younger than 45.
What did you find?
GS: Worldwide in 2010 there were about 184,000 deaths linked to drinking sugary beverages (133,000 diabetes deaths; 45,000 from cardiovascular disease; 6,000 from cancer). This is not just a problem in rich countries: About three-quarters of the deaths were in low- or middle-income countries. Among the world’s 35 largest countries, Mexico (which has one of the highest per capita consumptions of sugary beverages in the world) had the greatest death rate with 24,000 deaths (or 318 deaths per million adults). Japan had the lowest death rate associated with sugary beverage consumption.
How did the United States fare?
GS: Among the 35 largest countries in the world, it had the third-highest death rate, with about 25,000 deaths in 2010.
How do sugary drinks kill people?
GS: Sugary beverages lead to obesity, and obesity in turn leads to cardiovascular disease and diabetes. There are also specific cancers, such as breast, colorectal, gallbladder and pancreatic, that are strongly associated with obesity. They also lead to diabetes independent of obesity, disrupting the normal regulation of blood-sugar levels, leading to insulin resistance.
What is the take-home message?
GS: It shows that tens of thousands of deaths are caused by sugary beverages and that should compel policy makers to make effective policies to reduce consumption.
GS: There have been studies on a number of policy interventions to reduce sugary beverage consumption, such as taxation, controlling advertising and hosting media campaigns to tell people to reduce consumption. All of these policies are effective to various degrees, but they have to be implemented for us to see how well they work. Whenever a policy maker is trying to implement something like this, they deserve praise.
This study has been criticized for not being published in a peer-reviewed journal. Is that coming?
GS: One of the criteria for presenting work at the AHA meeting is that it has not been published elsewhere. We will certainly publish these results in a peer reviewed journal in the future.
An alternative perspective: Cause and effect questionable
The American Beverage Association is calling a study linking 184,000 annual global deaths to sugar-sweetened beverages “more about sensationalism than science” that makes a “huge leap” when alleging beverages cause deaths, “which the authors themselves acknowledge are due to chronic disease.”
In a statement, the ABA notes that many other factors, including ethnicity, age and lack of exercise can contribute to diabetes and points to a Journal of Nutrition study which “found no association between digestible carbohydrates, including sugar, and diabetes risk.” When it comes to heart disease, the ABA notes “atherosclerosis was found in ancient Egypt and other cultures long before sugar-sweetened beverages were invented.”
Rachel Johnson, PhD, chairwoman of the nutrition committee for the American Heart Association, says the Harvard study is an important one because of the sheer size of the data. But it has limitations. While it is “biologically plausible” that excess sugar sweetened beverages could lead to death, an epidemiological study such as the Harvard one “cannot prove cause and effect,” she says.
Johnson notes that research has shown that added sugars are associated with cardiovascular risk factors and obesity.
The AHA recommends people limit their consumption of added sugar to 100 calories (6 teaspoons) per day for women, or 150 calories for men. The average American consumes 22.2 teaspoons of added sugars per day.