SALT LAKE CITY, Utah — Your hair says a lot about you, but does it tell people what you eat for dinner too? A new study finds the compounds that make up your food end up creating the hair on your head. Researchers believe these chemical traces not only tell what’s in your diet, but may also reveal how much your regular haircut costs!
A team from the University of Utah reveals hair strands preserve many of the markers in the proteins you consume. The amino acids that build hair are so strong they show whether you prefer veggie burgers or cheeseburgers for lunch.
You are what you eat
Professor Jim Ehleringer says as food breaks down, isotopes in the meal (like carbon and nitrogen) travel throughout the body and into the hair. Studies from 2008 find this is also true about water. It can vary in its ratios of oxygen and chemical isotopes according to where it comes from on Earth. Based on those differences, scientists can actually trace where people have traveled via the water in their bodies.
“We then began consideration of what we could learn from carbon and nitrogen isotopes in the hair,” Ehleringer says in a university statement.
In this study, researchers find there are distinct differences in your isotopes depending on what livestock eats. Basically, the food an animal eats before it becomes your dinner is the key to revealing your diet.
Livestock raised on concentrated animal feeding farms are usually fed corn. Corn is considered a “C4 plant,” a group which includes sugarcane and photosynthesizes differently than legumes or vegetables. Just like your body, the corn absorbs into an animal’s body. If you eat protein that lived on corn, amino acids that create your hair have chemical ratios just like corn.
The same cycle applies for people who eat proteins that once lived on legumes or vegetables, which are “C3 plants.”
Can hair really show your income level?
Ehleringer’s study then focused on collecting hair samples from local barbershops and salons across the United States. The research looks at clippings from shops in 65 cities and 29 ZIP codes in Utah’s Salt Lake Valley area. In total, researchers gathered random hair samples from about 700 people.
After testing these samples, a pattern emerged showing a link between the isotopes in hair and the average cost of living in the ZIP codes they came from. The study finds corn-like isotopes are more common in hair from poorer economic areas. Meat-eaters who get their protein from cornfed animals from mass produced meat plants have higher levels of corn isotopes too.
Amazingly, data from the Utah samples also shows a link between carbon isotopes in hair and the price of a haircut at the shop it comes from.
“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,” the Utah researchers write.
Risk for obesity also revealed
The links between diet and income level have been regularly studied by nutritionists. It turns out these hair samples reveal another aspect of that connection — obesity.
Researchers say when they add in driver’s license data — to find trends in body mass index for certain ZIP codes — the results show a link between the hair isotopes and obesity rates. Ehleringer explains this data, locked in your hair, can help communities address local health and dieting issues.
“This measure is not biased by personal recollections, or mis-recollections, that would be reflected in dietary surveys,” the distinguished professor of biological sciences says. “The measurement can be used to understand dietary choices among different age groups and different socioeconomic groups.”
The study appears in the journal Proceedings of the National Academy of Sciences.