Each strand of hair on the head holds a record of a person’s eating habits - a fact that may allow doctors to objectively diagnose eating disorders, preliminary research suggests.

Scientists at Brigham Young University have developed a test that may be able to diagnose anorexia and bulimia by analyzing the nitrogen and carbon content of just a few strands of hair.

Right now, diagnosis of these disorders relies heavily on the patients’ honesty about their eating habits and body image. This is a significant obstacle because women with anorexia or bulimia often deny that they have a problem.

An objective measurement such as the new hair test could help confirm a suspected eating disorder, as well as help monitor patients’ recovery, according to the study authors, led by Dr. Kent A. Hatch.

He and his colleagues at the Provo, Utah, university report their findings in the journal Rapid Communications in Mass Spectrometry.

For hair to grow, proteins have to be added to the base of the strand, and the composition of these proteins is influenced by diet. So each strand essentially contains a record of dietary intake over time.

For their study, Hatch and his colleagues measured the carbon and nitrogen ratios in hair samples from 20 women with anorexia, bulimia or both, and from 23 healthy women. They found that the test was able to identify those with an eating disorder 80 percent of the time.

The test needs further refinement before it can be used in practice, according to the researchers. But this preliminary success, they say, is promising.

“We believe that the current work shows that the method is already quite robust,” Kent said in a statement.

While there are already certain objective ways to diagnose eating disorders - such as very low weight in anorexia - much depends on patients’ ability to recognize and admit their problems, Kent noted.

“This test,” he said, “has the potential of providing an objective, biological measure for diagnosing eating disorders.”

SOURCE: Rapid Communications in Mass Spectrometry, November 30, 2006.