Sweeteners ‘could cause obesity’ scientists warn

Artificial sweeteners could cause more weight gain than just having sugar, scientific trials suggest

By Laura Donnelly and National News

Artificial sweeteners in diet drinks and food could cause obesity and diabetes, new research suggests.

Experiments on mice and humans suggest that common sugar alternatives alter the metabolism, causing blood sugar levels to rise and triggering diseases by altering bacteria in the gut.

The trial on humans who were given the supplement saccharin suggested such changes to the body could begin to occur after just four days.

Scientists involved in the study said the widespread use of the chemicals in diet drinks and food could be contributing to the obesity and diabetes epidemic sweeping the world.

Others expressed caution, highlighting the fact that the majority of the research was carried out on mice, with just seven people involved in the human trials, which involved very high intake of sweeteners.

Previous studies have suggested that artificial supplements such as Canderel and Sweetex could trigger a “sweet tooth” – so that those who consume them are more likely to seek out sugary foods afterwards.

But the new research published in Nature suggests artificial supplements themselves could alter the metabolism of the body, making it easier to put on weight.

Scientists added one of the three most common supplements (saccharin, sucralose or aspartame) to the water of mice and found they altered metabolism, raising blood glucose to much higher levels than among mice who were given sugar.

When they used antibiotics to deplete the gut bacteria, the glucose intolerance caused by the supplements was eliminated, showing the supplements were to blame.

Next, they transferred the microbiota from mice that consumed artificial sweeteners to ‘germ-free’ mice – those with no gut bacteria of their own – resulting in a complete transmission of the glucose intolerance.

This showed the changes to the gut bacteria were responsible for the changes in metabolism.

Analysis found changes in the bacteria that are known to infer a propensity to obesity, diabetes and complications of these problems in both mice and humans.

A separate study of 400 humans found that those who regularly consumed artificial sweeteners had very different gut bacteria to those who did not. They also had higher blood sugar levels and were more glucose intolerant – putting them at greater risk of obesity and diabetes.

Seven volunteers who did not normally consume the artificial sweeteners were asked to consume very high levels of saccharin for a week – equivalent to 40 cans of diet cola a day.

After just four days, most had elevated blood sugar and altered gut bacteria, mirroring the results seen in the mice.

The researchers believe certain intestinal bugs reacted to the chemical sweeteners by secreting substances that then provoked an inflammatory response similar to sugar overdose, promoting changes in the body’s ability to utilise sugar.

Glucose intolerance, generally thought to occur when the body cannot cope with large amounts of sugar in the diet, is the first step on the path to metabolic syndrome and obesity related diabetes, the form that develops in adulthood.

The researchers said the findings were “alarming” and said those trying to lose weight should think again about consuming sweeteners.

Dr Eran Elinav, of the Weizmann Institute of Science, Rehovot, Israel, said: “Our relationship with our own individual mix of gut bacteria is a huge factor in determining how the food we eat affects us.

“Especially intriguing is the link between use of artificial sweeteners – through the bacteria in our guts – to a tendency to develop the very disorders they were designed to prevent; this calls for reassessment of today’s massive, unsupervised consumption of these substances.

“Some studies have suggested artificial sweeteners may be beneficial, while others have suggested they have a tendency to make people more obese and glucose intolerant. Our results are designed to understand a new mechanism, and we have gone a long way to finding one.”

He added: “Regarding sugary drinks, we are by no means saying they are healthy. What we are saying is there are changes promoted by artificial sweeteners, in some individuals. The finding is alarming and needs to be corroborated. We were surprised by the results, which is why we replicated them many times.”

Professor Naveed Sattar, who reviewed the findings for the journal, described them as “interesting’ but advised caution in extrapolating those concerning the mice to humans.

He said larger studies in humans had not found a “meaningful link” between diet drinks and diabetes risks, whereas sugary beverages were associated with higher diabetes risk.

“These findings would not make me choose sugary drinks over diet drinks,” he said.

Dr Nita Forouhi, Programme Leader at the MRC Epidemiology Unit, University of Cambridge said the studies in mice had made an important advance in understanding how supplements could cause metabolic disturbance, but said far more research was needed in humans.

“The findings in humans are currently inconclusive, being based on seven individuals, testing only one artificial sweetener (saccharin) in very high doses at the upper limit of the acceptable daily intake – equivalent to about 40 cans per day of a typical artificially sweetened cola-type drink,” she said.

Dr Katarina Kos, Senior Lecturer and Consultant in Diabetes and Endocrinology at the University of Exeter, said: “The study is based primarily on mouse experiments and only seven human subjects were studied. The findings require further confirmation prior to making firm conclusions. Larger scale human studies and funding are urgently required controlling for overall calorie intake. “

She said water was the healthiest drink option.
Artificial sweeteners in diet drinks and food could cause obesity and diabetes, new research suggests.