The diverse wilderness of life inside of our bodies is just starting to gain the attention of scientists. The human gut alone typically holds some 100,000 billion bitty bacteria, and with no two people's microbiomes being the same, classifying these crucial organisms has been challenging.

A new study, published online April 20 in Nature, proposes a simple schematic for profiling people's gut microbiota, breaking down these helpful hangers-on into three overarching categories. (Scientific American is part of Nature Publishing Group.)

"The three gut types can explain why the uptake of medicines and nutrients varies from person to person," Jeroen Raes, a bioinformatician at Vrije University in Brussels and coauthor of the new study, said in a prepared statement. "This knowledge could form the basis of personalized therapies," by basing treatments on the known metabolic tendencies of a person's microbiota category.

The study profiled the gut flora of 39 people from Europe, the U.S. and Japan and found that categories were not dependent on location—or on age, gender or body mass index.

"We may have uncovered a new 'biological fingerprint' on the same level as blood types and tissue types," Oluf Borbye Pedersen, a professor at the Faculty of Health Sciences at the University of Copenhagen and a research on the study, said in a prepared statement. Having one of the three types, which are characterized by a dominate genus of bacterium—Bacteroides, Prevotella or Ruminococcus—might play a large role in determining how you metabolize food to what vitamins your stomach is good at formulating (those in the Bacteroides group, for example, had a gut environment that was better at making vitamins B2, B5, C and H; those in the Prevotella group had more B1 and folic acid-making bacteria).

The researchers point out that this profiling is still in an early stage, but, Pedersen noted, down the line the new discoveries "may be translated into individual diet advice or design of drugs that are adapted to the individual."

Image courtesy of iStockphoto/kaarsten