In a recent French study, researchers observed that the consumption of sugary beverages can increase the risk of cancer. This applies not only to soft drinks but also to juices with 100% fruit content.
Based on an earlier mouse study that suspected accelerated cancer growth from sugar in soft drinks, researchers now investigated the link between sugary drinks and cancer. They found that the amount of consumption played a decisive role.
The team led by Eloi Chazelas studied the link between different types of cancer and the intake of sugary drinks in 101,257 French adults, with an average age at 42 years old. They obtained the data from the NutriNet-Santé study.
The beverages examined included those containing sugar, such as soft drinks, syrups or fruit juices, but also 100% juices without added sugar, milk-based beverages, and energy drinks.
The researchers also investigated artificially sweetened beverages. "This category includes all beverages that contain sweeteners with no nutritional value. These include light soft drinks, sugar-free syrup, and low-fat milk drinks."
By using digital 24-hour meal surveys, the scientists were able to monitor the consumption of 3,300 different types of food and drink. In addition, the clinical observation of the patients lasted over nine years.
During this time, the research team observed the risks for cancer in general and breast, prostate and colon cancer in particular. The researchers considered potentially decisive criteria such as age, gender, education, family cancer risks and lifestyle factors such as smoking or sport/exercise.
2,193 study participants at an average age of 59 contracted cancer for the first time. Among these were 693 cases of breast cancer, 291 cases of prostate cancer and 166 cases of colon cancer. The evaluation showed that a daily increase in sugary beverages by 100 ml increased the overall cancer risk by 18% and the breast cancer risk by 22%.
When evaluating the juices with 100% fruit content, the researchers discovered the same risks for general cancer and breast cancer. However, they found no association with colorectal cancer or prostate cancer.
In contrast, increased consumption in diet drinks does not increase the risk of cancer. The researchers assume that the participants consumed these only in very small quantities and recommend that this result be evaluated only cautiously.
The researchers argue that the scope and the long-term testing of the drinks speak for the strengths of the study. However, they also warn against generalizing the results, as the study is not representative of the majority of the population.
They note: "Since the majority of NutriNet-Santé study participants were women with high health awareness and higher educational attainment than the average French population, there may be a lower risk of cancer than the national average.''
Further limitations would be that causality and potential measurements cannot be accurately determined. Nevertheless, scientists believe that sugary drinks can increase the risk of cancer because sugar affects visceral fat, blood sugar, and inflammatory markers - all of which have been associated with an increased risk of cancer in previous studies.
The researchers conclude: "The results support common dietary recommendations to limit the consumption of sugary beverages, including 100% juices. In addition, policy measures should be taken to reduce the consumption of sugary beverages, which can be potentially carcinogenic".
Chazelas E et al, Sugary drink consumption and risk of cancer: results from NutriNet-Santé prospective cohort. BMJ 2019; 366: 2408