Sweeteners may worsen obesity, type II diabetes

Artificial sweeteners used widely in processed foods may worsen obesity and Type II diabetes by disrupting our gut microbes. A new study found that sweeteners commonly used for diet foods and reducing calorie intake lead to glucose intolerance, a precursor to many metabolic disorders involved in the modern obesity epidemic.

Artificial sweeteners such as aspartame, saccharin, and sucralose are typically considered less fattening than natural sugars such as glucose or sucrose because they contain little or no calories. The study said that doctors frequently suggest patients suffering from obesity and Type II diabetes substitute natural sugars with artificial sweeteners to reduce calorie intake. However, regularly consuming artificial sweeteners could actually worsen obesity or Type II diabetes.

The study, published last week in Nature by the Weizmann Institute of Science in Israel, used dietary trials on mice and humans. Mice were divided into two groups. One group was fed a low-fat diet and the other group was fed a high-fat diet, which was meant to replicate a modern high-fat diet in humans. Half of each group was also fed either natural sugars or artificial sweeteners. After 11 weeks, the high-fat diet mice which were fed artificial sweeteners had developed glucose intolerance, or the inability to break down sugar before it enters the bloodstream. Glucose intolerance is a symptom and a common precursor to Type II diabetes in humans.

The study then took the gut flora from the mice that had developed glucose intolerance and implanted them in those mice that had not. These previously healthy mice also developed glucose intolerance, showing that the gut bacteria were its causative agent in this case. 

Analyzing the composition of this compromised gut flora showed that species of bacteria associated with type II diabetes in humans had become more dominant.

Some healthy mice were also injected with gut flora cultured with artificial sweeteners outside of mice’s guts, which then also developed glucose intolerance.

The study had a two-component human analysis as well. A correlation test among 400 questioned participants found a link between metabolic disorders and the regular consumption of artificial sweeteners. 

Seven volunteers who didn’t regularly consume artificial sweeteners and who were of good health were also fed the maximum daily amount of artificial sweeteners for a week. Four of these seven developed glucose intolerance in that time, while the other three were unaffected.

Not all seven volunteers developed glucose intolerance. The difference between the tests is likely the product of more individualized gut flora in humans than in mice because mice regularly consume other mice’s feces.

How artificial sweeteners lead gut flora to induce glucose intolerance is still uncertain. They may induce an inflammatory response when certain microbe species become more or less dominant.

The study said behavior also has a role in the development of glucose intolerance, but to what extent is uncertain. 

These findings indicate the possibility for individualized dietary or nutritional therapy based on gut flora.

This is the first study to examine the effect of artificial sweeteners on our gut flora, which include cellular bacteria, fungi, and archaea, and outnumber our body cells ten to one. Previous correlation research had found links between artificial sweeteners and metabolic disorders, but could not find a causative agent.

Artificial sweeteners are not digested, so they come in direct contact with the microorganisms that reside in our intestines and other digestive organs. Research has shown that gut our gut flora can have powerful effects on behaviour and mood, based primarily on diet. 

Health Canada said it has not yet reviewed the study’s findings to inform its regulation of artificial sweeteners. The European Food Safety Authority has already said that the findings might change the European Union’s regulatory policy. 

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