EXPERT REACTION: Are sugary drinks giving you cancer?

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French researchers have discovered a possible association between drinking lots of sugary drinks and an increased risk of cancer. The team looked at results from dietary questionnaires from over 100,000 participants examining 3,300 food and drink items over a maximum of nine years. They found that an additional 100 mL increase in drinking sugary drinks was associated with an 18 per cent increased risk of overall cancer, and a 22 per cent increase in the risk of breast cancer. This type of study cannot prove cause and effect, and the authors suggest cautious interpretation. However, they add that limiting sugary drink consumption, together with taxation and marketing restrictions, might contribute to a reduction in cancer cases.

Journal/conference: BMJ

DOI: 10.1136/bmj.l2408

Organisation/s: Flinders University, Griffith University, The University of New South Wales, The University of Sydney, Paris 13 University, France

Funder: The NutriNet-Santé study was supported by the following public institutions: Ministère de la Santé, Santé Publique France, Institut National de la Santé et de la Recherche Médicale (INSERM), Institut National de la Recherche Agronomique (INRA), Conservatoire National des Arts et Métiers (CNAM), and Université Paris 13. BS was funded by the French National Cancer Institute (grant number INCa_8085) and the Fondation de France. Researchers were independent from funders. Funders had no role in the study design, the collection, analysis, and interpretation of data, the writing of the report, and the decision to submit the article for publication.

Media Release

From: The BMJ

Peer-reviewed? Yes
Evidence type: Observational
Subjects: People

Study suggests possible link between sugary drinks and cancer

Findings suggest limiting sugary drinks might contribute to a reduction in cancer cases, say researchers

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.

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Nikolai Petrovsky is a Professor in the College of Medicine and Public Health at Flinders University. He is also Research Director, Vaxine Pty Ltd

While this paper shows an interesting possible association between sugary drinks consumption and cancer risk, there are so many caveats to this type of study design that the findings should be just viewed as interesting and hypothesis generating, rather than meaningful in terms of establishing any actual link, as the authors themselves concede.

To suggest that 'Findings suggest limiting sugary drinks might contribute to a reduction in cancer cases, say researchers' [from the BMJ press release] goes well beyond the ambit of this paper and is a gross over extrapolation of the results, even when tempered by the use of the word 'might' in the statement.

What is needed is a better understanding of what might be driving this apparent association, for example if the people drinking the extra sugar were not necessarily more overweight than the controls then this must mean they were consuming less calories in solid food, all things being equal. So it is just as plausible that this could be the true explanation for the effect, as less solid food might translate to less plant based antioxidants and other anticancer molecules. This is consistent with their data showing that, compared with lower consumers of sugary drinks, higher consumers tended to have higher energy, carbohydrate, lipid, and sodium intakes and lower alcohol intake, compared with lower consumers.  Hence a more plausible explanation might be that intake of sugary drinks is just a marker of someone with an overall poor diet and this poor diet is actually  what is driving cancer risk.

The article does highlight one important point which is commonly missed, high sugar natural fruit drinks which are flourishing worldwide and being marketed  as a 'healthier option' by juice and smoothie companies can be just as bad if not worse than the carbonated drinks they are attempting to replace as in many cases they can have an even higher total sugar content. The population continues to be conned into thinking that 'natural' automatically equates to 'healthier' which is simply not the case.

Last updated: 22 Apr 2020 4:56pm
Declared conflicts of interest:
None declared.
Professor Margaret Morris is from the School of Medical Sciences and Head of the Environmental Determinants of Obesity Group at the University of New South Wales (UNSW Sydney)

The paper by Chazelas et al, which is published in BMJ, shows a disturbing increase in the risk of some cancers associated with the intake of sugar-sweetened beverages.

While the increased risk was relatively modest, the work comes from a large cohort study, including five years follow up.

In addition to sugar-sweetened beverages, 100% fruit juices were also found to increase the risk, but importantly, no such relationship was observed for artificially sweetened beverages.

This association between sugary drinks and the risk of cancer might be explained in part by their effect on overweight and obesity, which are known to be a risk factor for certain cancers, however the link held following adjustment for body mass index or weight change.

The authors conclude that the sugary drinks widely consumed as part of our so-called ‘western’ diet represent an opportunity for cancer prevention.

This work adds to the evidence for detrimental impacts of sugary drinks, and will provide impetus for other large scale studies, as well as work investigating the possible underlying mechanisms.

Last updated: 10 Jul 2019 5:37pm
Declared conflicts of interest:
None declared.
Melanie McGrice is an Advanced Accredited Practising Dietitian with a Masters degree in nutrition. She is a founding member of the Early Life Nutrition Coalition.

The Australian Dietary Guidelines recommend limiting sugar intake and focusing on drinking water and milk, and this paper adds to the body of evidence that recommends that consumption of sugar-sweetened drinks should be limited as they are not good for our health.

Research also suggests that soft drinks increase the risk of tooth decay, impact fertility and can contribute to excess calorie consumption. Sugar intakes in Australia have been falling over the past few decades, however around one in every two Australian adults consume soft drinks at least once per week, so there is definitely room for improvement.  
We do, however, need to remember that the risk of cancer is increased by many other factors too, so although it is worth reducing your consumption of sugar-sweetened beverages, it’s essential to look at your whole dietary intake and lifestyle.

Last updated: 10 Jul 2019 5:36pm
Declared conflicts of interest:
None declared.
Brian J. Morris is Professor Emeritus of the School of Medical Sciences and Bosch Institute at the University of Sydney

A new large study, published in the British Medical Journal, reports that sugary beverages, including soft drinks but also 100% fruit juice, increase overall cancer risk.

It involved over 100,000 French adults with an average age of 42 years who were followed for nine years. During this time they recorded consumption of over 3,000 different food and beverage items. During the follow-up period over 2,000 cancers were diagnosed for the first time, with age 59 years being the average age of diagnosis.

For each 100 ml increase per day in sugary drink consumption, there was an 18% increase in overall cancer. Women represented 79% of subjects and this amount of sugary drink consumption increased breast cancer by 22%. For higher consumption there was proportionately higher cancer risk.

100% fruit juice with no added sugar posed the same cancer risk as sugary soft drinks.

Diet beverages did not increase cancer risk. Like sugar, they do, however, increase the risk of diabetes and heart disease, as shown in numerous previous studies.

The workers took numerous other factors into account in their data analyses, so increasing the reliability of their findings.

They suggested that the mechanism involved a sugar-induced increase in fat surrounding vital organs in the body, particularly the liver and pancreas, as well as in insulin resistance, and inflammation inside the body. All of these are linked to cancer risk.

The link with cancer is probably worse than the study found. This is because the subjects studied were on average at the upper level of educational and socioeconomic level and thus had a relatively healthy diet and lifestyle than the rest of the population. Longer follow-up and studies with more men might be expected to detect a link with other cancers.

The researchers said that their findings add to calls for a tax on sugary drinks, bans on advertising, restrictions on marketing, to which I would add education starting with parents and children and the removal of vending machines that dispense unhealthy ‘food’,  i.e., a similar combination of approaches that have proven so effective in cutting the smoking rate.

Last updated: 10 Jul 2019 5:33pm
Declared conflicts of interest:
None declared.
Dr Lennert Veerman is Professor of Public Health at Griffith University. He has published on a broad range of topics including obesity and other risk factors for chronic disease.

While the association between the consumption of sugary drinks and an increasing number of cancers was known, this study is the first to convincingly link these drinks directly to cancer risk. Much of the cancer risk is likely to arise via obesity. This points once again to the need to reduce the consumption of sugary drinks for health.

Sugar should be treated much like alcohol and tobacco. While an information campaign would be helpful, it is unlikely to have a significant impact on its own. Taxation and advertising restrictions are probably also needed. Modelling studies have shown that both can lead to large improvements in health. They are likely to be good for the economy too: a healthy population is a more productive population.

As Adam Smith, often considered the founding father of economics, wrote in ‘The Wealth of Nations’ in 1776: 'Sugar, rum, and tobacco, are commodities which are nowhere necessaries of life, [but] which are ... objects of almost universal consumption, and which are therefore extremely proper subjects of taxation.

Last updated: 10 Jul 2019 4:51pm
Declared conflicts of interest:
None declared.
Associate Professor Allison Hodge is from Cancer Council Victoria’s Cancer Epidemiology and Intelligence Division

Our study demonstrated a clear link between sugary soft drink consumption and obesity-related cancers. The more sugary soft drinks participants drank, the higher their risk of cancer. This was not the case for diet soft drinks, suggesting the high levels of sugar in these drinks were a key contributor.

While there were differences in our cohort study and the French cohort, in terms of age and obesity status, the results clearly show the impact of sugary drink consumption on cancer risk.

Today's findings add weight to the growing evidence of the link between consuming sugary drinks and cancer risk. 

We hope that this new research will educate people about the health risks associated with these drinks, and encourage them to reduce their consumption.

Last updated: 10 Jul 2019 4:49pm
Declared conflicts of interest:
None declared.
Jane Martin is Executive Manager of the Obesity Policy Coalition

The findings reflected those from a similar Australian study conducted by Cancer Council Victoria and the University of Melbourne, adding to the mounting evidence that the high levels of sugar in these drinks are contributing to cancer, and other chronic diseases.
Sugary drinks are the largest source of added sugar in Australians’ diets, and these drinks are already known to be a cause of obesity, which greatly increases the risk of 13 types of cancer.
Governments have a role to play in regulating the marketing and availability of these drinks. 
It’s virtually impossible to escape the enormous amount of marketing, price promotions and sponsorship by sugary drink companies. Young people drink more of these drinks than anyone else and corporations have created this demand and continue to bombard them with marketing on TV, social media and public transport. We need government controls around unhealthy marketing to protect children and young people from its pervasive influence. We also need to take sugary drinks out of schools, recreation facilities and hospitals to protect people and promote healthier options.
A 20 per cent health levy on sugary drinks would deter people from these cheap and very unhealthy drinks. Funds raised could be used to promote healthy eating in our community, in time reducing the cancer burden and associated health costs.

Last updated: 10 Jul 2019 4:47pm
Declared conflicts of interest:
None declared.

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