Your hair says a lot about your style, but it can also say a lot about what you've been eating and where you live.

That's why researchers in Ottawa have spent the last three years collecting and grinding up hair samples to create a database that they hope could help solve cold cases.

University of Ottawa scientists Gilles St-Jean and Michelle Chartrand are conducting a pan-Canadian database filled with the information gained by analyzing hair samples.

Police detectives could then turn to the database when investigating unidentified bodies to learn a little more about them.

Chartrand says the old adage that "you are what you eat," is actually true, when it comes to hair analysis.

"Everything that we eat goes into fuelling our body's tissues, including our hair," Chartrand told CTV's Canada AM earlier this week.

Chartrand, a researchassociated who specializes in environmental chemistry, explains that hair grows about one centimetre a month, so the length of time investigators can go back depends on the length of the hair they find.

"So if someone's hair is 12 centimetres long, that's approximately one year worth of information that we could get," she says.

Chartrand's team uses something called "isotope analysis," a chemical analysis method that looks for clues among three key elements in hair: carbon, hydrogen and nitrogen.

She explains that analyzing a hair's carbon and nitrogen can offer a glimpse into the type of food a person has eaten.

"It can also tell us your particular protein intake, so it can the difference between a vegetarian, a vegan and an omnivore," she says.

Analyzing the isotopes in the hydrogen in a strand of hair can offer a clue about where someone has lived.

"The way that this works is that water is different in different regions. So it varies in terms of its isotope profile -- so the hydrogen that's in the water," she says.

The isotopes in some water are heavier than others, and their proportions can vary depending on the latitude and how far away one is from the equator or the ocean.

Because people tend to drink their local water, "the signals we find in local water reflects what we find in people's hair," Chartrand explains.

Chartrand says many people ask whether dyed hair can skew the analysis. Surprisingly, most times it doesn't. Her team has conducted a small study in which they analyzed the differences between dyed hair and undyed hair.

"What we found was that for the isotope analysis, dyeing hair does not have a significant on the results. Dyed hair and undyed hair give very similar results. That was very encouraging for us because a lot of people colour their hair," she said.

Chartrand says it's likely that hair dye simply stays on the shaft of the hair and doesn't penetrate it, so doesn't interfere with the hair's chemistry. Henna-dyed hair, on the other hand, is a different story; that gives results that are completely different from hair without henna.

For the last three years, Chartrand have been building a database of those signals, mapping out where certain hydrogen isotopes are found and where they aren't.

To build that database, they've been travelling the country, taking hair samples from long-time residents.

"So we can sample their hair and analyze it and say, 'Okay, this is the kind of signal we can expect from someone who lives in, for example, Ottawa'," she says.

"So when there's an identified body that's found, we can analyze their hair and compare it against our database to give us clues as to where that person has been spending most of their recent time."

The RCMP's Forensic Laboratory Services are doing their part too, by including trace elements from soils and quartz grains collected during the research team's sampling work.

And a group at the Universite de Montréal is building the first modern pollen database from the sampling efforts as well.

At the moment, all the data is housed with each of those groups and at the University of Ottawa, but they will all be brought together in 2012, when the full database is established.

The project is funded by the Centre for Security Science, a joint endeavour between Defence Research and Development Canada and Public Safety Canada.