A study published by The BMJ today reports a possible association between higher consumption of sugary drinks and and an increased risk of cancer.
While cautious interpretation is needed, the findings add to a growing body of evidence indicating that limiting sugary drink consumption, together with taxation and marketing restrictions, might contribute to a reduction in cancer cases.
The consumption of sugary drinks has increased worldwide during the last few decades and is convincingly associated with the risk of obesity, which in turn is recognised as a strong risk factor for many cancers.
But research on sugary drinks and the risk of cancer is still limited.
So a team of researchers based in France set out to assess the associations between the consumption of sugary drinks (sugar sweetened beverages and 100% fruit juices), artificially sweetened (diet) beverages, and risk of overall cancer, as well as breast, prostate, and bowel (colorectal) cancers.
Their findings are based on 101,257 healthy French adults (21% men; 79% women) with an average age of 42 years at inclusion time from the NutriNet-Santé cohort study.
Participants completed at least two 24-hour online validated dietary questionnaires, designed to measure usual intake of 3,300 different food and beverage items and were followed up for a maximum of 9 years (2009-2018).
Daily consumption of sugary drinks (sugar sweetened beverages and 100% fruit juices) and artificially sweetened (diet) beverages 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 mL v 74.6 mL, respectively).
During follow-up 2,193 first cases of cancer were diagnosed and validated (693 breast cancers, 291 prostate cancers, and 166 colorectal cancers).
Average age at cancer diagnosis was 59 years.
The results show that a 100 mL per day increase in the consumption of sugary drinks was associated with an 18% increased risk of overall cancer and a 22% increased risk of breast cancer.
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.
In contrast, the consumption of artificially sweetened (diet) beverages was not associated with a risk of cancer, but the authors warn that caution is needed in interpreting this finding owing to a relatively low consumption level in this 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.
This is an observational study, so can’t establish cause, and the authors say they cannot rule out some misclassification of beverages or guarantee detection of every new cancer case.
Nevertheless, the study sample was large and they were able to adjust for a wide range of potentially influential factors.
What’s more, the results were largely unchanged after further testing, suggesting that the findings withstand scrutiny.
These results need replication in other large scale studies, say the authors.
“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,” they conclude.
Consumption of added sugars in America has increased considerably over time1. Dietary intake of caloric sweeteners including sucrose and high fructose corn syrup increased by nearly 40% between 1950-59 and 20002.
Consumption of added sugars from beverages, particularly, has increased.
Between 1977 and 2003 calories from added sugars in beverages increased by 90 kcal/day and those from added sugars in foods by 23 kcal/day in the U.S.3.
In spite of a decline in consumption of absolute calories of added sugars, percentage of total energy intake from added sugars has remained high3.
In light of the growing body of evidence highlighting unfavorable health effects of added sugars, the 2015 Dietary Guidelines Advisory Committee recommended that Americans limit sugar to no more than 10 percent of daily calories4. Intake of high fructose corn syrup or added sugars has been associated with metabolic syndrome, characterized by elevated blood pressure, triglycerides, LDL cholesterol, uric acid, and inflammation5–7.
Not surprisingly, there is some evidence that dietary added sugars are associated with cancer, although the evidence is limited.
Case-control and prospective studies have shown an association of consumption of sugary foods8, 9, and particularly beverages10, 11, with increased risk of pancreatic cancer, which may be mediated in part through induction of transketolase12.
Additionally, sweet foods and beverages were shown to increase breast cancer risk by 27%13.
Recently, we reported an association between sugary beverages (fruit juices and sugar- sweetened) and reduced survival among head and neck cancer patients14.
Little is known about the associations of dietary added and concentrated sugars with the development of prostate cancer, although it is understood that lifestyle plays an important role in prostate cancer prevention15.
Because of the putative link between chronic inflammation and prostate cancer, dietary items that are potentially pro-inflammatory deserve particular attention.
It has been shown, for example that heterocyclic amines promote the development of cancer and induce accumulation of inflammatory cells (lymphocytes and macrophages) in the prostate16, that processed meat or dietary fat from meat is associated with increased prostate cancer risk17,18 and there is some evidence that dairy consumption may be associated with increased prostate cancer risk19.
It is possible that the increased fructose and consequently triglycerides in items with concentrated sugars promotes an inflammatory response that supports DNA damage and genetic changes leading to neoplastic lesions of the prostate6, 20–22.
We hypothesized that consumption of sugar-dense items, or items with concentrated sugars lacking the phytonutrients and fiber found in plant-based foods is particularly problematic, having a more detrimental impact on blood sugar, and ultimately promoting inflammation and prostate cancer growth.
The goal of the current study was to examine the association of concentrated sugars with prostate cancer risk.
The term concentrated sugars was defined as sugars (in grams) from sugar- sweetened beverages and fruit juices as well sugars in refined and processed desserts, constituting at least 30% of total calories, with prostate cancer risk.
Thus, this included added sugars in beverages and dessert foods, as well as natural sugars in fruit juices, which are naturally present in high amounts.
These associations were evaluated in men receiving usual medical care in the prospective, population-based Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial.
More information: Sugary drink consumption and risk of cancer: results from NutriNet-Sante? prospective cohort , BMJ (2019). DOI: 10.1136/bmj.l2408 , http://www.bmj.com/content/366/bmj.l2408
Journal information: British Medical Journal (BMJ)
Provided by British Medical Journal