Do zero-calorie sweeteners increase diabetes risk?
Artificial sweeteners repeatedly have attracted negative headlines, and they did again last month when a study in the journal Nature suggested they may promote glucose intolerance – a risk factor for diabetes.
Again and again, food safety organisations, including the European Food Safety Authority (EFSA), have refuted concerns about artificial sweetener consumption. EFSA has reviewed aspartame safety six times since it was first approved for use in Europe in 1994, most recently last year, concluding that there was “no reason to revise” its opinion on the sweetener’s safety at current consumption levels.
Meanwhile, researchers continue to examine potential risks from zero-calorie sweetener consumption.
This latest study centred on research in mice fed water sweetened with saccharin, aspartame and sucralose, at levels equivalent to the maximum permitted by the US FDA. When compared to mice that drank water or sugar water, the team found that these mice were more likely to develop glucose intolerance.
Sweeteners: Not a ‘magic bullet’
Dr Nita Forouhi, programme leader of the MRC epidemiology unit at the University of Cambridge, called the research “a series of elegant experiments in mice”.
She added: “This research raises caution that [non-caloric artificial sweeteners] may not represent the ‘innocent magic bullet’ they were intended to be to help with the obesity and diabetes epidemics, but it does not yet provide sufficient evidence to alter public health and clinical practice.”
The main reason for this is that the research was carried out in mice – and only seven humans. Furthermore, only four of the seven humans showed poor responses to a glucose challenge. While mouse studies are often a useful first step on the road toward research in people, their diet and physiology are very different from ours.
‘No real human story’
Principal dietitian at St George’s Hospital NHS Trust, Catherine Collins, said: “There’s no real human story here at all.”
She pointed out that a typical mouse diet consists of about 60% fat, with about 25% carbohydrates; people’s diets tend to be about 30% fat and 50% carbohydrates.
“This mouse dietary profile is bound to influence the results as found,” she said. “…Our naturally higher carbohydrate intake has generated bowel bacteria happily digesting whatever we swallow, and their symbiotic relationship with our bowel cells and beyond is testimony to this. This is significantly different to the lab mouse and can’t be discounted when trying to suggest cross-species effect.”
This is not the first time zero-calorie sweeteners have been linked to metabolic effects, but experts have been unified in a call for more controlled studies in humans.
Senior lecturer and consultant in diabetes and endocrinology at the University of Exeter, Dr Katarina Kos, said: “Larger scale human studies and funding are urgently required controlling for overall calorie intake.”
Others have claimed that zero-calorie sweeteners could be harmful simply by increasing desire for sweet foods and drinks. However, a recent study tested that hypothesis, and the results suggested that people who consumed diet soft drinks did not eat more sugary (or fatty) foods.
