February 27, 2009

Saliva May Provide Clues To Human Development

Researchers said on Thursday that bacteria found in human spit does not vary much around the world, a finding that could provide insights into how diet and cultural factors affect human health.

Experts say the human body harbors 10 times more bacterial cells than human cells and researchers are hoping to learn more about the diverse array of microbial species we carry in our mouths.

While little is known about the diversity of the bacteria found in people's spit and how it relates to diet, environment, health and disease, scientists know that the mouth is a major gateway for bacteria into the body.

Mark Stoneking of the Max Planck Institute in Leipzig, Germany, who led the study, told Reuters they were interested in the bacteria because they would gain more insight into human populations than they would get from just studying the human DNA.

For the study, the researchers sequenced bacteria found in saliva samples taken from 120 healthy volunteers from North America, South America, Western Europe, Eastern Europe, Africa and Asia.

They noticed considerable diversity of bacterial life in the overall saliva microbiome, both within and between individuals.

However, they found little variation after comparing samples from different geographic areas, suggesting that bacteria within the mouth of a person's neighbor is likely to be just as different as someone on the other side of the world.

The team believes the results could help science to better understand human migrations and populations as well as providing background for future studies looking at the influence of diet, cultural factors and disease on differences in saliva bacteria.

Stoneking said the saliva microbiome does not vary substantially around the world, which seems surprising given the large diversity in diet and other cultural factors that could influence the human salivary microbiome.

The full study was published online in Genome Research.


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