The blood and urine of 11 men, who he jokingly called “weird” for their indifference to chocolate, were compared to 11 similar men who ate chocolate daily. They were all healthy, not obese, and were fed the same food for five days.

The researchers found that a dozen substances were significantly different between the two groups. For example, the amino acid glycine was higher in chocolate lovers while taurine (an active ingredient in energy drinks) was higher in people who didn’t eat chocolate. Also chocolate lovers had lower levels of the bad cholesterol, LDL.

The explanation was that the difference in these two groups was due to difference in their bacteria naturally living in guts. Everyone has a vast community of microbes in their guts. But people who crave daily chocolate show signs of having different colonies of bacteria than people who are immune to chocolate’s allure.

That may be true for other foods, too. The idea could eventually apply to treating some forms of obesity by changing the composition of bacteria in our intestines and stomach.

The study was done in Switzerland and published in the peer-reviewed Journal of Proteome Research.

It is still unclear how and when bacteria are changing and made troubles.

How gut bacteria affect people is a hot field of scientific research.

Past studies have shown that intestinal bacteria change when people lose weight, said Dr. Sam Klein, an obesity expert and professor of medicine at Washington University in St. Louis.

Since bacteria interact with what you eat, it is logical to think that there is a connection between those microbes and desires for certain foods, according to Dr. Klein.

Ref: The Journal of Proteome Research: http://pubs.acs.org/journals/jprobs/index.html