Artificial sweeteners modify the intestinal flora with harmful effects
Saccharin and other artificial sweeteners modify the intestinal flora in a way that facilitates weight gain, hinders blood sugar level control and increases the risk of type 2 diabetes . It is the conclusion of an investigation by the Weizmann Institute of Rehovot (Israel) that is presented in the journal Nature and that will force us to reconsider the massive use of artificial sweeteners in the food industry.
"Our results indicate that artificial sweeteners induce the same problems that they intend to prevent, " said Eran Elinav, co-director of the research, at a telephone press conference. But he adds that these results "are not the last word" on the issue, but the first, so "it would be premature to make general recommendations on the consumption of sweeteners."
Unlike sugar, artificial sweeteners usually pass through the digestive system without being digested. For this reason they do not contribute calories. But for this same reason they arrive intact to the intestinal flora - the bacteria that populate the large intestine.
Since the food we eat regulates intestinal flora, and since intestinal flora regulates health, researchers wondered if artificial sweeteners could have any relevant effect.
To find out, they conducted a series of experiments on mice and "we were surprised that the effect was so great, " says Eran Segal, also co-director of the Weizmann Institute research. Subsequently, they conducted two studies on people who confirmed the results.
Experiments in mice have shown that when an animal ingests saccharin, aspartame or sucralose, the blood sugar level rises more than when it ingests sugar.
They have also shown that sweeteners modify the composition of the intestinal flora. Specifically, they reduce the bacteria of the genus Bacteroidetes - which are an antidote against obesity - and increase those of the genus Firmicutes.
To ensure that the intestinal flora is the key to the effect of sweeteners on blood sugar, they have performed a transplant of intestinal bacteria from mice fed with saccharin to mice that had never taken saccharin. The results have dispelled the doubts: after the transplant, the blood sugar level has skyrocketed.
In people, the results have been equally significant. In a first study, the consumption of artificial sweeteners has been evaluated in a sample of 381 people who answered a nutritional survey. The answers have revealed that, the more frequent the consumption of saccharin, the greater the weight of a person is usually and the higher the blood sugar level is usually. In addition, extra pounds tend to accumulate in the abdomen, which is where they are most harmful to health.
When performing blood tests on regular consumers of saccharin, abnormally high levels of glycosylated hemoglobin (indicating the concentration of blood sugar in the previous three months) and of the ALT enzyme (indicating liver damage and which the researchers attribute to a fatty liver disorder).
In a second study, seven healthy people who were not regular consumers of artificial sweeteners have agreed to take 360 milligrams of saccharin daily for a week, a dose considered acceptable by the US Food and Drug Agency.
By the end of the week, four of the seven participants in the study had their ability to regulate blood sugar levels altered. The composition of its intestinal flora has also been altered throughout the week. In the other three participants, saccharin has had no harmful or beneficial effects.
A retrospective analysis has revealed that, before starting the experiment, the four people harmed by saccharin had a different intestinal flora composition than the other three people.
"Not everyone responds negatively to artificial sweeteners, " says Eran Segal. But "they can be harmful to a large sector of the population." For now there is no test that allows to know for whom they are harmless and for whom they are harmful.
"It is a very surprising and interesting investigation, " highlights Francisco Guarner, director of the digestive system unit at the Vall d'Hebron hospital and researcher specializing in intestinal flora. Guarner recalls that previous research had shown that digestive tract bacteria play an important role in type 2 diabetes and obesity. But "the influence of artificial sweeteners is an important novelty that can affect a large number of people."
Research has been limited to three of the most consumed artificial sweeteners. All three affect the ability to regulate blood sugar levels and the risk of diabetes, although saccharin has a more pronounced detrimental effect than aspartame and sucralose .
When researchers have been asked if other sweeteners such as stevia can have a similar effect, researchers at the Weizmann Institute have avoided pronouncement. "We have not analyzed stevia and cannot speculate on sweeteners that have not been studied, because different intestinal floras react differently to different sweeteners, " said Eran Elinav. Stevia, in addition, is a natural sweetener, while saccharin, aspartame and sucralose are artificial. But "our results invite these studies to be done ."
They have also avoided ruling on whether sugar is better than artificial sweeteners because " in no way do we want to understand that sugar drinks are healthy and should be recovered, " added Eran Segal.
Predictably a new phase of research on sweeteners will now be opened in which its effects on intestinal flora will be taken into account. These investigations will be aimed at looking for molecules that do not have the disadvantages of sugar or saccharin.
With the data available so far, "we do not believe there is sufficient basis to change dietary recommendations, " Elinav warned. But he has admitted that "for years I have been drinking large amounts of coffee and consuming sweeteners thinking that they were not harmful and personally I have made the decision to stop using them."
The results of the research "require a reassessment of the massive use of artificial sweeteners, " conclude the scientists at the Weizmann Institute in Nature .
By: Josep Corbella
Source: http://www.lavanguardia.com
Saccharin favors diabetes
