It may not just be tooth decay you need to worry about when it comes to sugary drinks: new research suggests that these sweetened beverages might also be raising the risk of oral cancer.
Researchers from the University of Washington crunched the numbers from a public health database, looking at records covering the dietary habits of 162,602 women, 124 of whom developed oral cancer over a 30-year period.
Compared with women who drank less than one sugary drink per month, those who indulged in one or more sugary drinks daily were 4.87 times more likely to develop oral cancer.
Those who didn't drink alcohol or smoke much or at all, but consumed one or more sugary drinks daily, were at 5.46 times higher risk of oral cancer than women who drank less than one sugary drink each month.
"The incidence of oral cavity cancer (OCC) is increasing among non-smokers and young individuals without traditional risk factors worldwide," write the researchers in their published paper.
"In this study, high sugar-sweetened beverage intake was associated with a significantly increased risk of OCC in women, regardless of smoking or drinking habits, yet with low baseline risk."
The structure of this study means it does not show direct cause and effect, because other factors may be involved that the researchers haven't accounted for. However, the association is strong enough to suggest there is some relationship here.
Traditionally, oral cancer is linked to risk factors such as smoking or chewing tobacco, drinking heavily, and human papillomavirus (HPV) infection. It's a real concern that oral cancer cases are quickly rising outside of these risk factors.
One reason that's been put forward for this is our changing dietary habits. The unhealthy foods many of us are now consuming on a regular basis could be triggering long-term inflammatory responses from the body's immune system.
"A Western dietary pattern has increasingly been recognized as a risk factor for gastrointestinal tract cancers and is characterized by high consumption of saturated fats, processed foods, and added sugars," write the researchers.
"Our hypothesis is that diets with higher added sugar may contribute to chronic inflammation, which may, in turn, contribute to the risk of OCC."
There are some limitations here – the study only looked at data for women, and covers a relatively low number of cancer cases – and the researchers are keen for more data to be collected and assessed on this potential link.
However, it's another compelling reason for us to watch what we drink as well as what we eat. The health dangers associated with sugary drinks aren't new, but we're now realizing just how harmful they can be.
"The methodology and quality of the study are excellent and the data has been analysed in great detail," says epidemiologist Raúl Zamora Ros, from the Catalan Institute of Oncology (ICO) in Spain, who wasn't involved in the research.
"More studies are needed to confirm these associations and also to assess whether soft drinks with artificial sweeteners would be just as harmful, as many people substitute one for the other."
The research has been published in JAMA Otolaryngology – Head & Neck Surgery.