Monday, February 8, 2010

Soda Causes Cancer, Could it be?

A study done in Singapore has found that drinking 2 or more sodas per week is associated with nearly twice the risk of pancreatic cancer than staying soda free. The study was published this month in the journal Cancer Epidemiology, Biomarkers, & Prevention and reported on WebMD.

It's no surprise that the beverage industry is doing all it can to discredit the study; however, the methods used seem surprisingly sound. In fact, while the American Beverage Association claims that other studies have shown no association between soda and pancreatic cancer, a 2005 study out of Harvard School of Public Health found that soda (i.e. sugar sweetened beverage) consumption was associated with increased risk of pancreatic cancer in women, particularly those who were overweight.

The main problem with the findings from the Singapore study is the small number of cases. While the number of participants in the study was quite large, only 140 cases of pancreatic cancer developed during the 14 year follow-up. Similarly, not many participants drank soda twice or more each week, so only 18 of the 140 cases were among frequent soda drinkers.

Since many of the pancreatic cancer cases were among non-soda drinkers, it's likely that there are other factors that play a more important role in developing pancreatic cancer.

Nonetheless, it can be difficult to tease apart the effect of specific dietary habits on the development of disease, like cancer. It is especially difficult in the US were soda consumption is so high.

Here are a few strengths of the Singapore study:
  • Participants included men and women
  • Diet was assessed at the beginning and participants were followed-up for 14 years
  • Beverage intake including soda and juice were assessed, and there was no relationship found between drinking juice and later risk of cancer
  • The study controlled for links between soda consumption and other risk factors for pancreatic cancer including age, smoking, diabetes and body mass index (BMI). This helped to isolate the effect of soda consumption on later development of pancreatic cancer.
I think this evidence should give frequent soda consumers pause. If not for preserving their waistline, maybe for other (more serious?) aspects of health.

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