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Many people know the craving for sweets and the bad conscience when all the chocolate has been eaten again. Most people think the problem is in the head. But that is only partly true. New studies with mice show that the intestinal bacteria also control the craving for sweets.
Mice without natural intestinal bacteria eat significantly more sugar and work hard for a sweet reward, according to a study published in the journal Current Biology study.
The researchers observed this when they gave two groups of mice a choice: to eat pellets with a high sugar content or normal grain pellets. In one group of mice, the team had previously killed all the intestinal bacteria with antibiotics. The remaining animals had a healthy microbiome.
Scoundrels for sweets
Both groups ate the same amount of normal food overall. But animals with a disturbed microbiome ate 50 percent more sugar pellets than mice with healthy intestinal flora.
A second experiment showed that the animals were willing to work hard for the sweet reward: they had to press a button again for each additional sugar pellet. Animals without a microbiome really worked hard: Some pressed the switch more than 50 times. Mice with a healthy bacterial community gave up after just a few attempts.
“So the animals with no bacteria were willing to work a lot harder for that sweet food. And that, to me, is clear evidence that the animals made a conscious choice,” said Sarkis Mazmanian, a microbiologist at the California Institute of Technology, Caltech, and co-author of the study.
Lactic acid bacteria curb the craving for sweets
In order to find out which bacteria control this addiction-like behavior, the researchers then gave the animals individual strains of microbes that occur naturally in the intestine. It was found that certain lactic acid bacteria curbed the animals’ craving for sweets.
It is still unclear how these microbes in the intestine control cravings. But Sarkis Mazmanian suspects that they produce neurotransmitters such as dopamine, which act on the brain and thus control the animal’s craving for sweets.
If these microbes had the same effect on us, we could use them to treat binge eating.
It remains to be seen whether these lactic acid bacteria can also keep people from snacking. However, many strains of bacteria produce surprisingly similar effects in mice and humans: mice into which researchers transplanted the intestinal bacteria of obese people also became obese.
And the intestinal bacteria of well-trained athletes allowed mice to last longer on the running wheel. Sarkis Mazmanian is therefore confident that a bacterial cure can also help people who eat sweet or fatty foods uncontrollably.
Microbes against binge eating
“If these microbes have the same effect on us, we could use them to treat binge eating. It arguably doesn’t help people with the wrong dietary habits that lead to weight gain or obesity and diabetes. But it could work for ‘binge-eating’ behavior,” Mazmanian said.
Studies have already shown that the intestinal microbiome is altered in people with certain eating disorders. Perhaps those affected do not need a lot of chocolate, but a bacterial cure that restores the balance in the intestine.