People who drink a daily glass of orange juice may be at greater risk of cancer than someone who avoids sugary drinks entirely, a new study suggests.
Each extra 100ml of squash, fizzy drinks or 100 per cent fruit juice a day was associated with an 18 per cent higher chance of being diagnosed with any kind of cancer, the research in French adults found.
This increased risk was also seen even when sugary drink consumption was broken down to look at 100 per cent fruit juices, the researchers from the French National Institute for Health and Medical Research (Inserm) found.
People who consumed a daily 150 ml glass of juice were on average 12 per cent more likely to be diagnosed with cancer during the study than the average juice drinker.
There was no increased cancer risk found in people who drank more artificially sweetened, diet drinks.
The study, published in the British Medical Journal (BMJ), cannot prove that it is the high sugar intake causing this extra risk directly.
However, the researchers said it was possible this was the case, and that sugar could be increasing risk independent of obesity - which is known to contribute to at least 13 types of cancer.
"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 targetting sugary drinks, which might potentially contribute to the reduction of cancer incidence," they wrote.
Fruit juices are currently exempt from the UK's "sugar tax" on sweetened beverages, but the finding adds to evidence suggesting that the levy should be expanded.
Ministers were reportedly contemplating including milkshakes and other sweetened milk-based drinks in the tax in the upcoming NHS Prevention Plan.
However the levy's existence is in doubt if Boris Johnson wins the Tory leadership contest as expected after he said he would freeze, so called "sin taxes" which could also include alcohol, tobacco and fast food.
The BMJ study analysed data from 101,257 people who were aged 42 on average at the start of the study and were typically followed up for five years.
Participants were quizzed on their consumption of 3,000 different food and drink items at six month intervals, and on average were shown to drink 92.9ml a day of sugary drinks or 100 per cent fruit juice.
So each 100ml on top of this was linked to an 18 per cent higher risk of cancer, and in women a 22 per cent higher risk of breast cancer diagnosis.
Pure fruit juice contains significant amounts of natural sugars and participants in the study drank around 56ml per day on average, roughly two cups a week.
As the risk held true even when controlling for body-mass index (BMI), the team said it was possible "being overweight and weight gain might not be the only drivers of the association between sugary drinks and the risk of cancer".
They pointed to other research which suggested that sugary drinks promoted body fat around the abdomen, even if a person was a healthy weight, which in turn promoted the growth of tumours.
Other explanations for the link between sugary drinks and cancer could be the high glycaemic load of sugary drinks, they said.
Dr Graham Wheeler, a senior statistician at University College London, said the study was large and well-designed but warned that the findings might not apply to a wider population.
He added: "Participants were followed on average for about five years, and 22 participants per 1,000 developed some form of cancer.
"So this means if 1,000 similar participants increased their daily sugary drink intake by 100ml, we'd expect the number of cancer cases to rise from 22 to 26 per 1,000 people over a five-year period.
"However, this assumes that there is a genuine causal link between sugary drink intake and developing cancer, and this still needs further research."
Speaking on behalf of the British Fruit Juice Association, registered dietitian Helen Bond said: "The findings of this observational study completely contradict previous clinical trials on 100 per cent fruit juice which makes me suspect that participants were not correctly reporting their consumption of 100 per cent fruit juice."
Gavin Partington, director-general of the British Soft Drinks Association, said the study "does not provide evidence of cause, as the authors readily admit".
He added: "Soft drinks are safe to consume as part of a balanced diet.
"The soft drinks industry recognises it has a role to play in helping to tackle obesity which is why we have led the way in calorie and sugar reduction."