Israeli researchers link artificial sweeteners with obesity
Consuming non-caloric sweeteners such as saccharin instead of sugar may promote obesity rather than prevent it, according to a study published in the scientific journal Nature.
The research, carried out at Israel’s Weizmann Institute, appears as health campaigners exert growing pressure on the food and drinks industry to cut the sugar content of their products – and many manufacturers are turning to artificial sweeteners instead.
The Weizmann scientists carried out a series of experiments with mice and people using three sweeteners – saccharin, sucralose and aspartame – that are commonly incorporated into low-calorie snacks and beverages. Sports and energy drinks often contain two different “intense sweeteners” as the chemicals are sometimes known.
The study found that all three induced metabolic changes such as glucose intolerance which are associated with diabetes and obesity, though the effect was strongest for saccharin.
“Artificial sweeteners were extensively introduced into our diets with the intention of reducing caloric intake and normalising blood glucose levels without compromising the human ‘sweet tooth’,” the Nature paper concludes.
“This increase in non-caloric artificial sweetener consumption coincides with the dramatic increase in the obesity and diabetes epidemics,” the authors say. “Our findings suggest that [sweeteners] may have directly contributed to enhancing the exact epidemic that they themselves were intended to fight.”
Although slimmers have been adding tiny tablets of saccharine to their tea or coffee instead of sugar for decades, the widespread addition of sweeteners to a wide range of processed foods and drinks is more recent.
Mintel, the consumer research company, estimates that 5.5 per cent of all food and drink products launched last year contained at least one sweetener, compared with 3.5 per cent in 2009 – an increase it attributes to the “demonisation of sugar”.
The findings could reinforce demand for natural sweeteners. Sales of zero-calories carbonated drinks have faltered recently despite their lack of sugar because of consumer concerns about artificial sweeteners. In response, Coca-Cola launched a naturally-sweetened Coke for the first time last year, having already experimented with Sprite. The new drink – Coca-Cola Life – has a sugar and calorie content that is two-thirds of regular Coke, helped by the addition of stevia, a natural sweetener.
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But independent experts said people should take care in interpreting the findings. “This research raises caution that non-caloric 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,” said Nita Forouhi of the UK Medical Research Council Epidemiology Unit in Cambridge.
Sir Stephen O’Rahilly, professor of medicine at Cambridge university, said the work appeared to contradict the findings of other studies that showed no association between the consumption of artificially sweetened drinks and the development of diabetes.
“This new report must be viewed very cautiously as it mostly reports findings in mice, accompanied by human studies so small as to be difficult to interpret,” Sir Stephen said.
The Israeli authors, however, insisted that their findings did chime in with research elsewhere showing links between artificial sweeteners, weight gain and diabetes risk. “In no way are we saying that sugary drinks are healthier than drinks with artificial sweeteners,” said Eran Segal of the Weizmann, “but these results should provoke debate about the current massive use of these sweeteners.”
The most original feature of the study is the way it provides a mechanism for the metabolic effects of artificial sweeteners. The researchers found that they caused big changes in the “gut microbiota”, the billions of beneficial bacteria that populate the human stomach and intestines. Medical experts have only recently come to appreciate that the microbiota play a vital role in metabolism and more generally in disease.
“The sweeteners have no calories and are considered to be inert,” said Dr Segal. “But in fact when they go through the gastrointestinal tract they encounter this huge ecosystem and disturb its balance.”
Though the Weizmann researchers are not ready to make recommendations for the general population, Eran Elinav, the study leader, said he personally had stopped putting artificial sweeteners into coffee as a direct result of the research.
“These findings support the widespread understanding that water is the healthiest drink option and that we should avoid sweet and sweetened drinks,” said Katarina Kos, a diabetes consultant at the University of Exeter. “Water is the best drink to control our blood sugar.”