Who knew a few strands of hair could pack such a powerful informational punch. It sounds preposterous at first, but researchers from the University of Utah were able to analyze dietary trends among different U.S. socioeconomic brackets using nothing but hair samples collected from participants.
By the end of the project, researchers estimated how much someone paid for their haircut based on only a few strands of their hair.
How is this possible? Unbeknownst to you, your hair has been keeping close track of your diet for your entire life. Everyone knows the human body needs food to survive, support itself, and thrive. Well, your hair is no different than any other part of your body. Each hair strand on an individual’s body is produced from the amino acids found in food. But, long after a hair has grown, trace protein isotopes from the food remain.
Analyzing these proteins can tell a whole lot about a person’s diet. For example, researchers say a hair sample can reveal if someone typically eats veggie burgers or bacon cheeseburgers. Beyond just figuring out go-to restaurant orders, though, the research team used collected hair samples to examine diet trends and subsequent health risks among different socioeconomic brackets of Americans.
“This information can be used to quantify dietary trends in ways that surveys cannot capture,” comments distinguished professor Jim Ehleringer, of the U’s School of Biological Sciences, in a release. “We would like to see the health community begin to assess dietary patterns using hair isotope surveys, especially across different economic groups within the US.”
All in all, the researchers’ efforts revealed that Americans living in poorer areas tend to consume more protein from corn-fed animals. On a larger scale, though, the success of this endeavor represents a unique, new way for scientists to examine dietary trends in the United States.
Naturally, once researchers realized they needed to collect hair samples, they got in touch with a group of barbershops and hair salons. Once everything was said and done, hair samples had been collected from haircutting establishments in 65 different U.S. cities. The Salt Lake Valley area made up a large portion of those samples (hair was collected from 29 ZIP codes in just that area alone).
“They would then let us go to the trash bin and pull out a handful or two of hair, which we then sort into identifiable clusters representing individuals.” professor Ehleringer explains.
Now, while samples from close to 700 different people ended up being collected, researchers had no idea about any of those individuals’ gender, age, income, or health issues. All they had to work with were the hidden isotopes within the hair samples.
Variations specifically regarding carbon isotope ratios in the hair samples proved to be the crux of this study and its findings. This was so important because the carbon isotope signature in corn is quite different than that of other vegetables or legumes. Essentially, people who usually eat protein that had been fed corn while alive show a different carbon isotope signature in their hair than people who eat more protein from plant sources or animals that were fed other vegetables.
An analysis of all the collected hair samples revealed that carbon isotope values indeed correlated with the cost of living. People living in poorer areas ate more corn-fed protein. Moreover, for samples collected in the Salt Lake Valley area, using nothing but a hair sample’s carbon isotope signature, the study’s authors were able to roughly estimate how much that person paid for their haircut.
“We had not imagined that it might be possible to estimate the average cost an individual had paid for their haircut knowing carbon isotope values,” professor Ehleringer notes.
A connection between isotope ratios in hair samples and obesity rates within a given ZIP code was also noted by the study’s authors. So, not only are people living in poorer areas eating more corn fed protein, but obesity is also more common in these regions. This finding, they say, confirms that hair sample analysis can be used in the future to examine health trends among Americans.
“This measure is not biased by personal recollections, or mis-recollections, that would be reflected in dietary surveys,” professor Ehleringer concludes. “As an integrated, long-term measure of an individual’s diet, the measurement can be used to understand dietary choices among different age groups and different socioeconomic groups.”
In the future, hair analysis may become a popular way to quickly and accurately assess either a single individual’s or an entire community’s eating habits. We often forget about certain food items we’ve eaten, but our hair remembers.
The full study can be found here, published in Proceedings of the National Academy of Sciences.