Findings from a study of more than 100,000 people over nine years suggests that reducing sugary drinks may reduce cancer risk.
The The NutriNet-Santé study by Paris 13 University, France, surveyed 101,257 health adults (21 per cent men, 79 per cent women) between 2009-2018. Participants completed at least two 24-hour online validated dietary questionnaires, designed to measure usual intake of 3300 different food and beverage items during the research period.
While the link between the increase in sugary drinks consumption over the last few decades and the risk of obesity is well recognised – and obesity is recognised as a strong risk factor for many cancers – there is limited research on cancer risk and sugary drinks
Researchers wanted to assess the association between the consumption of sugary beverages (sugar sweetened drinks and 100 per cent fruit juices), artificially sweetened drinks and the risk of overall cancer as well as breast, prostate and bowel cancers.
The results show that a 100 millilitre per day increase in the consumption of sugary drinks was associated with an 18 per cent increased risk of overall cancer and a 22 per cent increased risk of breast cancer.
Daily consumption of sugary and artificially sweetened drinks were calculated and first cases of cancer reported by participants were validated by medical records and linked with health insurance national databases.
Several well known risk factors for cancer, such as age, sex, educational level, family history of cancer, smoking status and physical activity levels, were taken into account.
Average daily consumption of sugary drinks was greater in men than in women (90.3 millilitres versus 74.6 millilitres).
During the follow-up, 2193 first cases of cancer were diagnosed and validated (693 breast cancers, 291 prostate cancers, and 166 colorectal cancers). The average age at cancer diagnosis was 59 years.
When the group of sugary drinks was split into fruit juices and other sugary drinks, the consumption of both beverage types was associated with a higher risk of overall cancer. No association was found for prostate and colorectal cancers, but numbers of cases were more limited for these cancer locations.
While consuming artificially sweetened (diet) beverages was not associated with a risk of cancer, the authors warn that caution is needed in interpreting this finding because of a relatively low consumption level in the sample.
Possible explanations for these results include the effect of the sugar contained in sugary drinks on visceral fat (stored around vital organs such as the liver and pancreas), blood sugar levels, and inflammatory markers, all of which are linked to increased cancer risk.
Other chemical compounds, such as additives in some sodas might also play a role, they add.
The authors note that it is an observational study, so can’t establish cause, and some misclassification of beverages or detecting of every new cancer case can not be ruled out.
But the study sample was large and they were able to adjust for a wide range of potentially influential factors. The results were largely unchanged after further testing, suggesting that the findings withstand scrutiny. The authors say the results need replication in other large scale studies.
“These data support the relevance of existing nutritional recommendations to limit sugary drink consumption, including 100 per cent fruit juice, as well as policy actions, such as taxation and marketing restrictions targeting sugary drinks, which might potentially contribute to the reduction of cancer incidence,” they say.
Flinders University College of Medicine and Public Health, Professor Nikolai Petrovsky says there are many caveats on the study and the findings “should be just viewed as interesting and hypothesis”. He says a better understanding is needed of what might be driving the apparent association.
Petrovsky says: “The article does highlight one important point which is commonly missed, high sugar natural fruit drinks which are flourishing worldwide and being marketed as a 'healthier option' by juice and smoothie companies can be just as bad if not worse than the carbonated drinks they are attempting to replace as in many cases they can have an even higher total sugar content. The population continues to be conned into thinking that 'natural' automatically equates to 'healthier' which is simply not the case."