Sweeteners commonly used in diet soft drinks could increase the risk of cancer, a large study claims.
Experts from the French National Institute for Health and Medical Research, and Sorbonne Paris Nord University, tracked the diet and health of 100,000 people over eight years.
They found a 13 per cent higher rise of cancer risk for people who regularly consumed artificial sweeteners.
This highest risk was observed for the sweeteners aspartame and acesulfame-K, both used in the UK in soft drinks like Diet Coke and Coke Zero, as well products like yogurts and even cheese.
Previous large-scale studies on humans have found no such association and UK experts said no causal link had been found.
If true, the finding would relate to about three more cancer cases per 10,000 people over eight years, according to one analysis of the findings.
But independent UK experts pointed out several limitations of the study and said they were still not convinced, claiming it ‘does not prove or even suggest that we should go back to sugar and turn our backs on artificial sweeteners’.
This highest risk was observed for the sweeteners aspartame and acesulfame-K, both used in the UK in soft drinks like Diet Coke and Coke Zero and are used as a sugar substitute in tea
The French researchers looked at the diet and health records of 102,865 French adults who had an average age of 42. Three-quarters were women.
Data was gathered an ongoing log-term nutritional study in which participants submit 24-hour dietary records every six months.
Researchers compared their artificial sweetener intake to cancer diagnoses reported by the participants up to January 2021.
About 37 per cent of participants knowingly consumed artificial sweeteners at least once a day.
By the end of the study 3,358 had been diagnosed with cancer, with their average age at the time their disease was found being 59.5 years.
Of these, 982 were breast cancers, 403 were prostate cancers and 2,032 were obesity related cancers.
What does the NHS say about artificial sweeteners?
Aspartame and acesulfame-K are two of several artificial sweeteners approved for use in the UK.
Dietitian Emma Carder states: ‘Research into sweeteners shows they’re perfectly safe to eat or drink on a daily basis as part of a healthy diet.
She also says they’re a really useful alternative for people with diabetes who need to watch their blood sugar levels while still enjoying their favourite foods.
‘Like sugar, sweeteners provide a sweet taste, but what sets them apart is that, after consumption, they do not increase blood sugar levels,’ she says.
It’s been suggested that the use of artificial sweeteners may have a stimulating effect on appetite and, therefore, may play a role in weight gain and obesity.
But research into sweeteners and appetite stimulation is inconsistent. Also, there’s little evidence from longer term studies to show that sweeteners cause weight gain.
The findings suggested those people consuming larger quantities (typically 79mg per day) of artificial sweeteners had a 13 per cent higher risk of overall cancer compared to those having none.
The findings were strongest for aspartame and acesulfame-K, both sweeteners that are approved in the UK. They are about 200 times sweeter than normal sugar.
Higher risks were observed for breast cancer (22 per cent increased risk for aspartame) and obesity-related cancers, the scientists said.
The study had several limitations, including that those in the study were more likely to be women and to be health-conscious.
The researchers said: ‘Our findings do not support the use of artificial sweeteners as safe alternatives for sugar in foods or beverages and provide important and novel information to address the controversies about their potential adverse health effects.
‘While these results need to be replicated in other large-scale cohorts and underlying mechanisms clarified by experimental studies, they provide important and novel insights for the ongoing re-evaluation of food additive sweeteners by the European Food Safety Authority and other health agencies globally.’
Dr Michael Jones, senior staff scientist in genetics and epidemiology at the Institute of Cancer Research (ICR), London, said the current consensus ‘is that there is no clear evidence that artificial sweeteners cause cancer in humans’, although the issue is frequently looked at.
He added: ‘The link between artificial sweeteners and cancer reported in this study does not imply causation – it is not proof that artificial sweeteners cause cancer.
‘The types of people who use artificial sweeteners may be different in many ways to those who do not, and these differences may partly or fully explain the association.’
Fiona Osgun, senior health information manager at Cancer Research UK, said: ‘This large study suggested there’s an association between some artificial sweeteners and cancer, but that doesn’t mean they cause it or that people need to avoid them.
‘While the researchers have tried to find out what people were eating and account for other factors that could affect cancer risk, this is a single study that relies largely on self-reports.
‘What we eat and drink overall is much more important than one single element of our diet – so aim to eat more fruit, veg and wholegrains, and cut back on red and processed meats and foods high in fat, sugar and salt.’
Dr Duane Mellor, from Aston University, said the findings related to about ‘three more cases of all types of cancer per 10,000 people over an average of about eight years’.
He pointed to weaknesses in the study, adding: ‘This study does not prove or even suggest that we should go back to sugar and turn our backs on artificial sweeteners or diet drinks.’
Professor Tom Sanders, from King’s College London, said: ‘It is well known that women who are obese or who have a tendency to gain weight are more likely to use artificial sweeteners and this limits the validity of the conclusions of this study because it is not possible to completely control for this in the statistical analysis.’
Dr Kotryna Temcinaite, senior research communications manager at Breast Cancer Now, said: ‘What we do know is that eating a balanced diet, maintaining a healthy weight and being physically active are steps people can take to help reduce their risk of breast cancer.’