Hair shows eating disorders

Researchers at Brigham Young University say that human hair is like a little cassette player that records nutritional and dietary status over time — and it can be used to provide a more accurate picture of what someone who is battling an eating disorder is eating.

Such "objective" information is important for diagnosing and treating disorders such as bulimia nervosa and anorexia because those who have them "often try to hide them or even deceive themselves they don't have an eating disorder," said Kent Hatch, an assistant professor in the department of integrative biology at BYU.

Hair analysis won't tell anyone how many beans you ate or whether you skipped or had dessert, but in blind sampling, mass spectrometry analysis was able 80 percent of the time to identify those with either anorexia or bulimia nervosa and those who do not have the eating disorders.

The researchers expect to refine the testing for even better results, said Hatch, lead author on the study, being published today in the journal Rapid Communications in Mass Spectrometry.

An estimated 1 percent to 5 percent of American females in their teens and early 20s have eating disorders, which can be deadly. While they're diagnosed based on measures such as body-mass index, they also require subjective evaluation and accurate input from the patients, which some are reluctant or unable to give, said Steve Thomsen, one of the co-authors and a professor of communications at BYU.

"Diagnosing an eating disorder is such a subjective thing when you ask about eating habits. I think that anything that helps us have a better idea what is going on is very, very helpful," said Morgan Crawford, a medical student at the University of Utah. As an undergraduate at BYU, Crawford worked with another BYU student, Amanda Kunz, to process most of the hair samples and analyze them for the study.

Hair is useful to explain dietary history for much the same reason it's used to test for illicit drug use. "It's really quite inert and stores signals well. It doesn't change a lot," said Hatch. Long after something leaves the bloodstream, it may be recorded in the hair, which is so stable that anthropologists have studied hair on intact mummies to see when corn was introduced into diets in Central America.

Hair acts as tiny time capsules because of the way it grows. New proteins are added to the base of the strand, which is then pushed up out of the hair follicle. What you consume influences the proteins of that moment's hair growth and patterns associated with eating disorders are discernible — such as whether someone is "using food they eat for energy or consuming their own tissue for energy" due to lack of protein, Hatch said.