Cancer risks of juices should not be sugar-coated
Could just one small glass of freshly squeezed orange juice really increase your cancer risk? A French research team believes that it could.
Their study, just published in the British Medical Journal, reports a strong possible association between higher consumption of sugary drinks and an increased risk of cancer.
The researchers — from the Sorbonne, French Public Health Agency and Avicenne Hospital
— readily admit that cautious interpretation is needed. Their study is associational and
therefore does not prove causation. However, it is large and well designed.
They say that their findings add to a growing body of evidence indicating that limiting sugary drink consumption with taxation and marketing restrictions might contribute to a reduction in cancer cases.
Their study leaves some experts wondering why most governments, including the SA government, and dietitians’ organisations such as the Association For Dietetics in SA and their members still promote fresh fruit juice as healthy.
Growing evidence shows the opposite.
The researchers say that consumption of sugary drinks has increased worldwide during the last few decades and is convincingly associated with the risk of obesity, which is well recognised as a strong risk factor for many cancers.
But research on sugary drinks and the risk of cancer is still limited, the researchers say. Thus, they set out to assess the associations between the consumption of sugary drinks (sugar-sweetened beverages and 100% fruit juices), artificially sweetened (diet) beverages, risk of overall cancer as well as breast, prostate and bowel (colorectal) cancers.
They looked at 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.
Data showed that an increase in consumption of sugary drinks of just 100 ml per day was associated an 18% increased risk of overall cancer and a 22% increased risk of breast cancer. (That ’with s relative, not absolute risk the one you really need to worry about. A relative risk of 18% is small, relatively speaking, and in this case therefore the absolute risk turns out to be negligible.)
OVERALL CANCER
And 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. The researchers found no association for prostate and colorectal cancers, but say that the numbers of cases were more limited for these cancer locations.
In contrast, they found that consumption of artificially sweetened (diet, “soft”) beverages was not associated with a risk of cancer. However, they warn caution is needed in interpreting this finding due to a relatively low consumption level in this sample.
They speculate on possible explanations for the results: the effect of the sugar in sugary drinks on visceral fat (the type that is stored around and “migrates” into vital organs, such as the liver and pancreas), blood sugar levels and inflammatory markers. All these are linked to increased cancer risk, the researchers say.
Other chemical compounds, such as additives in some sodas, might also play a role, they add.
They cannot rule out some misclassification of beverages or guarantee detection of every new cancer case.
However, they conclude that their data supports 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”.