Weizmann Inst: Sweeteners cause diabetes, obesity

artificial sweeteners
artificial sweeteners

A study found that artificial sweeteners adversely affect intestinal bacteria.

Artificial sweeteners like saccharin, aspartame, and sucralose have always been suspect, because they are materials not found in nature. Comprehensive studies conducted with them, however, have never produced any concrete proof of damage in humans, and the scientific community remains divided on whether they are more or less damaging than sugar. Weizmann Institute researchers have now discovered that the sweeteners affect the bacterial population of the intestine in a way that leads to diabetes.

Prof. Eran Segal, Dr. Eran Elinav, and PhD candidate Yotam Suez from Elinav's laboratory, who led the current study, examined the effects of the sweeteners in several ways on animals and humans. Among other things the study examined how a change in the quantity of sweeteners consumed by humans affects their blood sugar levels. For the first time, the mechanism through which the negative effect occurs was identified.

Should we completely give up sweeteners? The researchers also note the limitations of the study, and do not propose giving up sweeteners altogether at this point. They say that the study should be expanded and its findings replicated in larger groups and over time, and suggest examining more sweeteners. The study is slated for publication in the prestigious medical journal Nature.

Rising suspicion

Elinav and Segal are leading the Personal Nutrition Project. They sought to investigate the effect of bacterial composition in the intestine on the food that each person should eat. They first examined the diet of hundreds of people, and how it affected their blood sugar level (each participant in the study carried a continuous sugar meter) and their intestinal bacteria. Their aim was to see whether certain food causes an exceptional rise in blood sugar among people having or lacking certain bacteria. Initial findings from this study caused them to suspect artificial sweeteners.

At this point, the researchers turned to an initiated test (as opposed to observation) on mice. They gave groups of mice three types of artificial sweeteners: saccharin, sucralose, and aspartame, while the control groups were given only the powder in which the sweetener was mixed. Incidentally, the sweeteners also contain a certain quantity, albeit small, of ordinary sugar in order to mask the aftertaste of the sweetener.

The mice exposed to sweetener were three times as likely to become obese and diabetic than mice who consumed only the powder. The composition of their intestinal bacteria in tests was different from the second group of mice.

The researchers then examined the development of obesity and diabetes resulting from the intestinal bacteria. They implanted the intestinal bacteria of the mice who consumed saccharin in mice that had never been exposed to these bacteria, and found that this group also had a greater tendency to develop diabetes. Antibiotics killed all the bacteria, and equalized the blood sugar level of the two groups of mice.

These trials gave rise to a suspicion that intestinal bacteria were indeed responsible for the difference in the blood sugar levels among rats, but what about humans? In order to examine this point, two studies were conducted. One, based on information from the Personal Nutrition Project, showed that fatter and more diabetic people also consumed more sweeteners. By itself, this figure does not mean much, because it is possible that fat people and diabetics consume more sweeteners because they believe it will help them get slimmer. The researchers discovered, however, that in both groups of humans, those who consume sweeteners and those who do not, there are differences in the intestinal bacteria population.

Another study was conducted on seven volunteers who usually do not consume sweeteners at all, and who began to do so for the purpose of the study; their consumption was at a high rate, but not an excessive one: about 12 small packets of saccharin a day. The blood sugar level rose in four of them. A major difference in intestinal bacteria was found between those who had a negative reaction to saccharin and those who did not even before the trial, enabling the researchers to predict who would respond negatively to the sweetener. Seven subjects are certainly not enough to draw a definite conclusion, but in combination with the other data, they constitute supporting evidence that intestinal bacteria are responsible for the phenomenon.

What happened to the bacteria?

What happened to the intestinal bacteria, and how does this cause diabetes? "We think that consuming saccharin causes a certain population of intestinal bacteria to prosper, or poisons a certain other population of intestinal bacteria, enabling other bacteria to prosper in their absence," Elinav explains. "The new population that prospers after consumption of sweeteners is the same as the one identified as linked to obesity and diabetes in previous studies not dealing in sweeteners.

"These bacteria encourage obesity and diabetes in several ways. One is by breaking down the food we eat into elements that are easier for the body to digest. This means that in the presence of these bacteria, the utilization of energy from a given food can rise by an average of 10%." In other words, a person who has these bacteria will gain 10% more weight than a person who ate the same food, but who does not have these bacteria.

"Globes": In the trial, you did not compare the sweeteners to sugar. If someone feels they need to sweeten something, which is better?

Elinav: "We didn't test it, and the last thing we want is to drive people away from sweeteners back to sugar without testing this. Don't draw premature conclusions from the study."

What about natural sweeteners, such as stevia?

"We didn't test them; we'll do it later. Natural material isn't necessarily better or worse; there are natural materials that are terribly poisonous. Each material has to be tested individually."

Goodbye calories

"This study supports our approach, which holds that food does not have a single uniform nutritional value. Each person can produce a different amount of energy from each type of food. It depends on how this food is broken down by his own special intestinal bacteria," says Elinav. This means that if one person eats rice, he will get fat, while ice cream will not affect him, while the opposite can be true about someone else. In other words, counting calories the way people do when they go on a diet is meaningless.

Does this mean that someone who up until now has eaten according to some fixed menu of calories or points, and is not a participant in your diet project, can do a kind of study himself at home by taking note of what food makes his situation especially worse?

"In my opinion, no. We have developed a special computer algorithm that simultaneously tests many food elements, including the interactions between them, even at a difference of several hours. There are many surprises with each one of the subjects, and I don't think that a simply perusal of food and its result can lead to such personal conclusions. Our goal is to eventually classify the effect of different intestinal bacteria, so that when we test your intestinal bacteria, we'll be able to reach the same conclusions about what you should and shouldn't eat, without putting you through everything that we're doing in the project."

"Everyone has to make a decision about what works for him."

Clalit Health Services senior dietician Mariana Orbach is a great believer in Segal and Elinav's Personal Nutrition Project. "They are definitely going in the right direction, and they should be given a very large budget," she says, but expresses the same reservation as the researchers themselves: "Seven people make a very small study, and they investigated only a few isolated materials - only saccharin or only aspartame. Today, almost all sweeteners contain a mixture of several materials. Furthermore, they did not directly compare the sweetener to sugar, and the all-important question is whether using sugar or an artificial sweetener is preferable."

Orbach also criticizes the way the trial was conducted. "A recent study raises the possibility that sweeteners also play a role in the development of breast cancer," she says. "Estrogen is produced in the body, and is broken down in the intestine by bacteria found in some women, but not in others, after which it becomes a material that protects against breast cancer, but only in the group having the beneficial intestinal bacteria. I have always said that all diseases are in the intestine."

In a previous interview with her, Orbach said that her own experience also shows that people respond differently to different foods, and told about a patient who became obese by eating large amounts of lettuce. One of her theories is that the intestinal bacteria of that patient broke down the lettuce, which is usually not digested, into digestible materials, but as a dietician, Orbach has no way of testing this mechanism in depth.

"Globes": Will the current study change your recommendations to patients?

Orbach: "It will certainly make me pay more attention to this point. I'm already frequently recommending that diabetic patients start with a three-week diet of totally avoiding anything sweet, even sweeteners and fruit. Those who persist with it will continue to prefer non-sweet food even after this period ends, and they will have better chances of keeping their weight down. At the same time, I'm aware that this does not affect everyone the same way. I interview my patients in depth and in great detail in order to understand what diets they have been more successful with in the past, and what made them go off the wagon. In this way, I can direct them to food that is suitable for them. Everyone has to make a decision about what works for him.

"I congratulate these scientists, and I'm waiting for more accurate results of their work. The problem is that if a study comes out that weakens these results, it won't be put in a newspaper headline, so people will go around with wrong information for years. So I say to your readers, don't throw your sweeteners away yet."

Published by Globes [online], Israel business news - www.globes-online.com - on September 23, 2014

© Copyright of Globes Publisher Itonut (1983) Ltd. 2014

artificial sweeteners
artificial sweeteners
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