Soda and juices double your risk of getting rare cancer in the gallbladder, a study claims.
Emerging evidence suggests obesity and elevated blood sugar levels increase the risk of these malignancies.
Now the results of a 13-year study have been released showing sugar-sweetened drinks play a significant role in driving up that risk.
Compared with people who avoided sugar-sweetened drinks altogether, people who consumed at least two juice drinks or sodas a day had more than twice the risk of developing gallbladder tumors, according to experts at the Karolinska Institute in Sweden.
Soda drinkers also had a 79 per cent higher risk of getting biliary tract cancer - bile ducts in the liver - than their healthier counterparts, the study found.
People who consume at least two juice drinks a day had more than twice the risk of developing gallbladder tumors and a 79 per cent higher risk of cancer in the liver bile ducts, according to a new study
To explore the link between soda and cancer risk, researchers analyzed survey data on the eating and drinking habits of more than 70,000 adults then followed them for more than 13 years on average to see whether cancers got diagnosed.
At the start of the study, participants completed food and drink questionnaires that asked how many sodas or juice drinks they had consumed in the past week and how much they typically consumed during the previous year.
When they answered these questions in 1997, participants were 61 years old on average. About half of them were overweight and roughly 25 percent were current smokers.
Researchers excluded people with a previous cancer diagnosis or a history of diabetes.
The people who drank two or more sodas or sugary beverages a day were more likely to be overweight and eat a higher-calorie diet with more sugar and carbohydrates and less protein and fat.
The increased risk of gallbladder and biliary tract tumors persisted, however, even after researchers adjusted for whether participants were overweight.
Because the study is observational, the findings don't prove soda and sugary drinks cause cancer.
It's also possible that because researchers only had data on drinking habits at the start of the study, the findings might have been influenced by changes over time in the beverages people consumed, the authors note in JNCI: Journal of the National Cancer Institute.
Researchers also lacked precise data to assess how often the sugary drinks people chose were diet sodas, said Dr Margo Denke, a former researcher at the University of Texas Southwestern Medical School in Dallas who wasn't involved in the study.
While coffee is shown to be beneficial to the gallbladder (pictured) soda has been proven to damage it.
Even so, 'this study suggests that there is more than a plausible link; the incidence of biliary and gall bladder cancer was higher among individuals who consumed more sodas and juices,' Dr Denke said.
Lead study author Susanna Larsson of the Karolinska Institute.
'Soda consumption has been inconsistently associated with risk of biliary tract cancer (only one prior study) and other cancers in previous similar studies,' Larsson said by email.
Only about 150 people developed biliary tract or gallbladder cancers during the study period.
But the current study 'is the first study to show a strong link between consumption of sweetened beverages, such as soda, and risk of biliary tract cancer,' Larsson added.
The exact reasons for the connection between sodas and these tumors may be unclear, but the message for consumers is still simple, said Dr. Igor Astsaturov, a medical oncologist at Fox Chase Cancer Center in Philadelphia who wasn't involved in the study.
'Obviously, this finding signals again and again that healthy lifestyle is the key to cancer-free life,' Astsaturov said by email.
'Regardless of the cause, it is easy enough to quench the thirst with water to stay fit and healthy.'
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