Poor people eat more meat than the middle-classes who have a diet filled with more fruit and veg, study finds

  • Researchers discovered a way to look for different food proteins in human hair 
  • They found that people from poorer backgrounds eat a more meat heavy diet
  • The team say hair studies could help better analyse food and economic status 

Wether you eat a vegan or meat heavy diet and your socioeconomic status can be determined simply by looking at proteins in your hair, a new study found.

A study led by a team at the University of Utah examined proteins in discarded hair found in rubbish bins from barbershops and salons across 20 US states. 

They found a way to determine what you eat, where you’ve been, and even how much you paid for your haircut simply by looking at proteins in hair samples. 

Poorer people had higher proportions of protein coming from cornfed animals in their hair, whereas more wealthy people had proteins from fruit and vegetables. 

The US team discovered that hair isotopes matched closely to standards of living, where people live, what you’ve eaten and even how much your last haircut cost.

Poorer people had higher proportions of protein coming from cornfed animals in their hair, whereas more wealthy people had proteins from fruit and vegetables. Stock image

The team examined the source of proteins – plant or meat – found in hair samples and then looked at the socioeconomic status of the owner of the hair.

PROTEINS IN HAIR CARRY INFORMATION ON FOOD SOURCES 

The researchers are able to match different proteins in hair to the food or drink they source they originated from.

Different food sources have different ratios of stable isotopes, or atoms of the same element with slightly different weights.

As food breaks down into amino acids, the isotopes present in our food find their way into all parts of our bodies – including our hair.

For example, corn photosynthesises differently to vegetables and legumes.

Corn is in a group called ‘C4 plants’ and vegetables are ‘C3 plants’.

So if you eat protein that ate corn, the amino acids that comprise your hair will have isotope ratios more like corn.

If your protein comes more from plant sources or from animals who ate C3 plants, your hair will have an isotope signature more like C3 plants.

Water, which varies in its oxygen and isotope ratios according to geography, works the same way and could be used to determine where someone has been.

Next, the authors correlated the isotope information in the hair samples with US census socioeconomic data. 

Isotopes are atoms which differ in the number of sub-atomic neutron particles and scientists use this to predict details about the life of the person who grew the hair. 

For example, scientists can predict where you have been because of the water you drank – as seen in the isotopes – which is different from place to place.

They also found that  hair could be used to reveal socioeconomic status, as poorer people had higher proportions of protein coming from cornfed animals in their hair.

The researchers say their method could be used as a way to assess the health of entire communities at a time, and to spot health risks. 

Compared with plant-derived proteins, corn-fed animal-derived proteins were more common in the diets of individuals from low socioeconomic populations. 

‘Animal proteins accounted for 57 per cent of diets on average, and, in areas with low socioeconomic status , they accounted for as much as 75 per cent,’ they found.

 The findings suggest that consumption of corn-fed animal proteins is more common among lower economic populations than high economic populations,.

The team say this puts those in poorer communities at a heightened risk of illness. 

The study’s author, Jim Ehleringer, said: ‘This information can be used to quantify dietary trends in ways that surveys cannot capture.

‘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.’

Since the 1990s Ehleringer and colleagues Denise Dearing and Thure Cerling have been looking into the ways that traces of diets could be detected in hair.

Different food sources have different ratios of stable isotopes, or atoms of the same element with slightly different weights.

As food breaks down into amino acids, the isotopes present in our food find their way into all parts of our bodies – including our hair. 

Ehleringer said: ‘We then began consideration of what we could learn from carbon and nitrogen isotopes in the hair.

‘For livestock raised in concentrated animal feeding operations, the corn that they eat is incorporated into their tissues.’

He explained how corn is in a group of plants called ‘C4 plants’ which photosynthesise differently than ‘C3 plants’, a group that includes legumes and vegetables.

So if you eat protein that ate corn, the amino acids that comprise your hair will have isotope ratios more like corn.

If your protein comes more from plant sources or from animals who ate C3 plants, your hair will have an isotope signature more like C3 plants.

He added: ‘Those are the principles of hair isotope analysis, but this study is about the applications – and for that, we’ll need some samples of hair.’

A study led by a team at the University of Utah examined proteins in discarded hair found in rubbish bins from barbershops and salons across 20 US states. Stock image

The team mustered up hair samples from more than 700 people from 65 cities across the USA by rummaging through the bins are hairdressers.

A group of those samples were from 29 post codes in the Salt Lake Valley, Utah so they could study differences between areas that were close together.

Ehleringer said: ‘Barbers and salon owners were supportive. They would 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.

‘This sampling technique was blind to the individual’s age, gender, income, health status or any other factor, except for the isotope record.’

The samples collected from the Salt Lake Valley showed that carbon isotopes in hair matched with the price of the haircut at the sampling location. 

‘We had not imagined that it might be possible to estimate the average cost an individual had paid for their haircut knowing values,’ said Ehleringer.

They then went a step further and used driving license data to calculate trends in body mass index for particular post codes, the researchers found that the isotope ratios also correlated with obesity rates.

Ehleringer said: ‘This measure is not biased by personal recollections, or mis-recollections, that would be reflected in dietary surveys.

‘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.’  

Their findings have been published in the journal Proceedings of the National Academy of Sciences.

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