LONDON: It might be an insignificant part of the human body, but the tiny toenail holds the secrets of what we eat and where we live.

Detailed laboratory work carried out on a severed leg washed ashore on a Scottish beach, has revealed that a toenail can act as a chemical fingerprint of what we eat and drink and, more importantly, where we consume our food.

Eight months after detectives from Tayside Police discovered the severed limb, Professor Sue Black of the Department of Forensic Anthropology at Dundee University, found that the man, whose identity they are seeking to determine had dark hair, was 5ft 6in and aged between 16 and 25 years old.

However, a major step forward was taken by Wolfram Meier-Augenstein, a chemist at Queen's University, Belfast, who used a forensic technique, known as stable isotope profiling, and provided the investigators with an incredibly detailed picture of the unidentified man's movements around various parts of Europe during the last two years of his life.

Meier-Augenstein used samples taken from one of the man's toenails to tell detectives the victim had spent time in at least three different parts of northern Europe in the 20 months before his death.

Prof Black said that the science behind the amazing insight into the life of one man from a toenail, came down to what we eat, reports the Scotsman.

"It's smart science. The basic principle is that you are what you eat - that every single cell that we have in our body is made up from elements that we consume, whether we eat them or drink them or breathe them in. These stable isotopes are chemical compounds that exist within the food that we consume that we then lay down in our bodies," she said.

"With bone it can get laid down in all sorts of places, but with nail and hair it gets laid down in a time sequence so that you can almost read it. And the closer you get to the root of your hair, or the closer you get to your nail-bed, the more recent the indication of what you have been eating. It's like a timeline," she added.

Prof Black explained that the clues originate from the hydrogen, nitrogen, carbon and oxygen molecules in the toenail, which contain a record of the chemical element make-up of a person's dietary intake.

Det Sergeant Kevin McMahon, who is investigating the discovery of the severed limb, said that the leads provided by the scientists were "fascinating".

Isotope profiling has also been used to help identify a man whose torso was found in the Thames, enabling detectives to identify some of the life history and geographic point of origin of the murder victim.

Experts believe that the same sophisticated forensic techniques could be adapted to sketch the geographical movements of suspected terrorists and the origin and source of drugs.