Drinks that are 100% made from fruit with no added sugar may have a link to cancer risk, a new study finds.
For some time now, researchers have been linking sugary drinks with a wide range of health risks.
Now, new research further explores the link between sugary drinks and cancer. The observational study, appearing in The BMJ, finds an association between high intake of sugary drinks and cancer.
Eloi Chazelas, from the Sorbonne Paris Cité Epidemiology and Statistics Research Center in France, is the first author of the study.
Studying sugary drinks and cancer risk
Chazelas and team examined the links between the intake of sugary drinks and various forms of cancer in 101,257 French adults aged 42 years, on average. The researchers obtained the data from the NutriNet-Santé study.
The drinks they examined included "sugar-sweetened beverages" such as soft drinks, syrups, fruit drinks, 100% fruit juices without any added sugar, milk-based sugary drinks, sports drinks, and energy drinks.
The researchers also considered artificially-sweetened drinks, that is, "all beverages containing nonnutritive sweeteners, such as diet soft drinks, sugar-free syrups, and diet milk-based beverages."
Using 24-hour online food questionnaires, the researchers assessed the participants' consumption of 3,300 different kinds of foods and drinks. Furthermore, clinical observation of the participants continued for up to 9 years.
During this time, the researchers looked at the risk of "overall, breast, prostate, and colorectal cancer."
Chazelas and colleagues accounted for potential confounders, including age, sex, education, hereditary risk of cancer, and lifestyle factors — such as smoking behavior and exercise patterns.
A 22% higher risk of breast cancer
Over the follow-up period, 2,193 people developed cancer for the first time; they were 59 years old at the time of diagnosis, on average. Among all these cases were 693 of breast cancer, 291 of prostate cancer, and 166 colorectal cancer.
The analysis revealed that for a daily increase of 100 milliliters in the intake of sugary drinks, the risk of overall cancer rose by 18%, and the risk of breast cancer increased by 22%.
When the researchers analyzed the risk for 100% fruit juices separately, these also elevated the risk of overall cancer and breast cancer. However, the study found no links with colorectal cancer or prostate cancer.
By contrast, diet drinks did not increase cancer risk. The scientists explain that people who consumed diet drinks did so in very small amounts, so they suggest interpreting this particular result with caution.
Strengths and limitations of the study
Chazelas and colleagues also lay out the strengths and weaknesses of their research.
First, the "large sample size and its detailed and up-to-date assessment" of the drinks consumed strengthen the results, write the researchers.
However, the findings may not be widely generalizable, as the study cohort is not representative of the wider population, they continue.
"Since the participants of the NutriNet-Santé cohort were more often women," they say, "with health-conscious behaviors and higher socio-professional and educational levels than the general French population, this might have resulted in a lower cancer incidence compared with national estimates."
Other limitations include the inability to determine causality and potential measurement biases. However, the authors speculate that sugary drinks may raise cancer risk because the sugar affects visceral fat, blood sugar, and inflammatory markers — all of which previous studies have correlated with higher cancer risk.
The researchers conclude:
"These data support the relevance of existing nutritional recommendations to limit sugary drink consumption, including 100% 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."