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There are about 10 thousand species of microbes in a healthy person's body
Last reviewed: 01.07.2025

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The body of a healthy person is home to about 10 thousand species of microbes. This is the conclusion reached by American scientists who took part in a large-scale project called "The Human Microbiome".
As researchers have found out, many of these microorganisms are harmless or even useful. At the same time, in the body of every person, even an absolutely healthy one, there is always a small amount of harmful bacteria that cause various diseases under certain conditions.
The next step, the scientists say, will be to figure out what these conditions might be and how to prevent the development of diseases caused by microbes that are constantly present in the human body. In addition, the researchers will have to determine how the body distinguishes between "bad" microorganisms and "good" ones.
Knowing which microbes live in the human body could help us better combat the diseases they cause, such as obesity and Crohn's disease, according to researchers at the Genome Institute at the University of Washington in Missouri.
"Most of the time, the human body lives in harmony with microbes, but sometimes this harmony is disrupted, which leads to the development of diseases," says Eric Green, director of the National Human Genome Research Institute, located in Maryland. One of the goals of the project is to establish the possible causes of this "disharmony."
For the study, the scientists took 5,000 samples of saliva, blood, skin and feces from 242 people aged 18 to 40, whose health had been thoroughly checked beforehand. Using modern computer programs, they analyzed the DNA contained in the samples and determined which microbes were present in different parts of the body and in what quantities.
The Human Microbiome Project, which began five years ago and is sponsored by the National Institutes of Health, involves about 200 scientists from 80 research institutions and has cost $173 million.