Are we what we eat? This question has been much debated over the years, but a fast and cheap urine test might prove just that. 

Scientists in Australia, the UK and the US have created a urine test that can provide a person with a snapshot of what they have been eating and drinking over the previous 24 hours. 

The team also created a scoring system that allows a nutritionist to assess how healthy someone’s diet is. 

Historically, the only way to record what someone ate and drank was to rely on a person’s memory and what they noted down in a food diary, which is not normally very accurate.

“The problem is people are prone to forgetfulness. And they’re also prone to lying about what they’ve been eating,” said Jeremy Nicholson, a professor at Murdoch University in Perth and emeritus professor at Imperial College London, one of the lead researchers on this project.

What your urine says about your diet

Nuclear magnetic resonance (NMR) spectroscopy is a commonly used technique to measure levels of different chemicals in a mixture or to find out how pure something like a drug is. Samples to be tested are placed inside a machine that has a magnetic field and exposed to radio waves. This makes the chemicals vibrate and each one has a different vibration signature that the machine is able to read. 

“The beauty of NMR spectroscopy is it’s very fast and cheap to run,” said Nicholson. “The machines themselves are phenomenally expensive, but if you look at the overall lifetime of a NMR spectrometer, which is a long, long time, and how many samples it can do, it comes back with a cost per sample that can be as low as $17 for doing a test.”

In this case, the researchers tested levels of different chemical residues or ‘metabolites’ in people’s urine and linked them to specific foods or drinks they had consumed. They compared written records of everything almost 2000 volunteers in a US-based research study ate and drank over a 24 hour period with a test of their urine.

They found that it was possible to track what people had consumed over the 24 hours by measuring a range of different metabolites in their urine. 

For example, the test could measure alcohol and caffeine intake and sugar consumption, but also more healthy indicators such as whether the person had been eating fruit. In addition, it was able to pick up some chemicals linked with health problems such as obesity and high blood pressure.

“We found that this is actually much more predictive of what people have been eating than their recall of what they’ve been eating,” Nicholson told me. 

A healthy diet for you, might not work for me

In another part of the study, the scientists asked a small group of people to eat four different diets that ranged from very healthy (100% balanced) to unhealthy (25% balanced) over a period of time and tested their urine after they consumed each one. 

Notably the team found that two different people eating the same diet did not necessarily have the same test results and some diets were scored as being healthy for some people, but less so for others. 

“Not everybody responds to a good diet in the same way. So what is good for you may not be good for somebody else; it depends on your own biochemistry. An important part of how you interact with a diet is your individual pattern of gut microbes, because gut microbes are really very diverse,” said Nicholson.

The world of nutrition is notorious for fad diets and inaccurate information. The tests that Nicholson and his colleagues have created have real potential to provide accurate, unbiased information on how healthy a person’s diet is and to give them advice on what type of diet is most healthy for their body.  

“We created something called a dietary metabotype score or DMS, which captures all that variability and it gives a simple number about how healthy that particular diet is for you at any one stage,” explained Nicholson. 

In general, the higher the DMS score, the more healthy the person’s diet. For example, people with high DMS scores tend to have lower average blood sugar than people with low scores. 

People with high scores also seem to excrete more calorie-rich chemicals into their urine rather than absorbing them into their body, which the researchers think could be due to them having a ‘healthier’ population of microbes in their gut than those with lower scores. This difference equated to approximately 1500 calories a year, which translates to an estimated body fat difference of 215 grams between someone with a high and someone with a low DMS score. 

What’s next?

Nicholson cautioned that at present the test has been created using a mostly Caucasian population, but he says it would be straightforward to calibrate it for populations with different ethnicities. 

The test is only able to accurately measure recent diet from a few days prior to the time of testing, but if regular readings are taken over time then it could provide an accurate reflection of how someone’s diet varies over a longer period.

To allow these findings to be used on a wider scale, a spinout company called Melico was recently founded in the UK. Elaine Holmes, also a professor at Murdoch University and Imperial College London, Nicholson and five other researchers working on this project were co-founders of the company.

It has only recently been established, but Melico plans to provide dietary analysis of people’s urine in order to improve their dietary health with the help of specialist nutritionists. 

The researchers also want to investigate how these test results could be linked to someone’s risk of becoming obese or developing diabetes and high blood pressure.

They are also using the same technology to assess how healthy a specific food is, with a view to being able to verify a producer’s claim that a specific food is a ‘super food’ for example. It will also help to reduce food fraud where low quality or contaminated food is sold as ‘high quality’. 

“We are trying to link the quality of food to nutritional information so that you can actually put a health claim on a particular foodstuff, which means that the producer of that food could brand it as being a quality product that produces good physiological effects,” explained Nicholson, although he cautioned that this research is very early stage at the moment.