People who drink two or more sugar-sweetened soft drinks per week appear to be almost twice as likely to develop pancreatic cancer as people who consume no soft drinks, according to a University of Minnesota study published today in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
“The increase in blood sugar that happens dramatically after you drink a soft drink stimulates insulin in the pancreas,” said Mark Pereira, Ph.D., senior author on the study and an associate professor in the School of Public Health at the University of Minnesota, in a phone interview last week.
The part of the pancreas where tumors are most likely to develop becomes particularly flooded with insulin, he added.
Pancreatic cancer is relatively rare, but very deadly. Of the 42,000 Americans who are diagnosed with this cancer each year, only about 5 percent are alive five years later. Current known modifiable risk factors for pancreatic cancer include smoking, obesity, type 2 diabetes and exposure to certain pesticides and other chemicals. Diet may also play a role, particularly diets that include a lot of red and processed meats.
For the study, Pereira and his colleagues followed 60,524 men and women in the Singapore Chinese Health Study for 14 years.
During that time, 140 of the study’s participants developed pancreatic cancer. After adjusting for such potential confounding factors as cigarette smoking, obesity and diabetes, Pereira and his colleagues found that drinking two or more soft drinks increased the risk of pancreatic cancer by 87 percent.
“The average intake in those who consumed two-plus soft drinks a week was actually five a week, so a lot of them were consuming it every day,” Pereira said.
Why go to Singapore to do this study? Previous studies have found a similar correlation between soft drinks and pancreatic cancer in Caucasian populations, said Pereira. If the correlation is real, it should be found in different settings and among different groups of people, he said.
Interestingly, the study found no correlation between the consumption of fruit juice and pancreatic cancer. Pereira offered several possible explanations for why the sugar in fruit juice wouldn’t have the same effect as that in soft drinks: People who drink fruit juice regularly may have a healthier overall lifestyle. In addition, the nutrients in fruit juices, particularly antioxidants, may act as protective factors.
Furthermore, said Pereira, it’s possible that other additives in soft drinks are converted in the body to carcinogens.
Pereira stressed that his study has several limitations. “This is observational research, so we don’t draw strong conclusions” about cause-and-effect, he said.
In addition, participants self-reported their eating habits, a form of data collecting that can be unreliable. Also, although Pereira considered confounding factors when crunching his numbers, other unknown dietary or behavioral factors that weren’t controlled for (such as red meat consumption) may have influenced the findings.
Pereira hopes to do a meta-analysis next — a study that pools together data from many different studies to address some of the possible biases in this one.
Here is a video interview with Pereira.
Although the findings of the U of M study can’t be considered definitive in terms of pancreatic cancer, soft drinks — including sugarless diet ones — contain nothing of nutritional value and have been linked to obesity, type 2 diabetes and heart disease, as well as dental decay. Just last fall, some of our leading nutrition experts argued in the New England Journal of Medicine for an increased tax on soft drinks as a public health measure.
“Our study is just another reason to really limit your consumption of soft drinks,” said Pereira.