Most dieters have probably lied to themselves about their food intake at some point. But not being honest in food diaries when on a doctor-prescribed diet or study can introduce serious inaccuracies and complicate any weight loss attempts. Since it seems we can't be trusted, researchers have developed a urine test that can independently measure the health of a person's diet in just five minutes.

The test was developed by researchers from Imperial College London, Newcastle University and Aberystwyth University and measures biological markers in urine created when foods such as red meat, chicken, fish, fruit and vegetables are broken down as they travel through our bodies. Additionally, the test can also provide an indication of a person's intake of fat, sugar, fiber and protein.

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"A major weakness in all nutrition and diet studies is that we have no true measure of what people eat," says Professor Gary Frost, senior author of the study from the Department of Medicine at Imperial. "We rely solely on people keeping logs of their daily diets – but studies suggest around 60 per cent of people misreport what they eat to some extent. This test could be the first independent indicator of the quality of a person's diet – and what they are really eating."

The team's study involved 19 volunteers following four different diets, which ranged from very unhealthy to very healthy and were formulated using World Health Organization dietary guidelines. The volunteers followed their diets for three days and provided urine samples in the morning, afternoon and evening throughout the study. These samples were then analyzed for the presence of metabolites that are produced when certain foods are broken down in the body.

In addition to indicating foods like red meat, chicken, fish, fruit and vegetables, these metabolites can also indicate specific foods, such as citrus fruits, grapes and green leafy vegetables, and give a general picture of the amount of protein, fat, sugar and fiber eaten.

Using this information, the researchers were able to develop a urine metabolite profile indicating a healthy, balanced diet that included a good intake of fruit and vegetables. By comparing this "healthy diet" profile to the diet profile of an individual's urine could provide a quick and easy indication of whether the person is eating healthy or not.

To test the accuracy of the urine test, the researchers compared it to data from a previous study involving 291 volunteers who had kept information on their daily diets and provided urine samples. By analyzing these urine samples, the team was able to accurately predict the diet of the volunteers.

"For the first time, this research offers an objective way of assessing the overall healthiness of people's diets without all the hassles, biases and errors of recording what they've eaten," says Professor John Mathers, study co-author from the Human Nutrition Research Centre at Newcastle University.

However, the researchers point out that their work is still at the early stages and more needs to be done to improve the test. To this end, they are looking to conduct testing on more people and test its accuracy om an average person's diet outside of a research setting.

"We need to develop the test further so we can monitor the diet based on a single urine sample, as well as increase the sensitivity," says Dr Isabel Garcia-Perez, co-author from the Faculty of Medicine at Imperial. "This will eventually provide a tool for personalized dietary monitoring to help maintain a healthy lifestyle. We're not at the stage yet where the test can tell us a person ate 15 chips yesterday and two sausages, but it's on the way."

The researchers are hoping to have the test available to the public within two years, with the idea being people could collect their sample at home and deliver it to a local center for analysis, whether as part of a weight-loss effort, patient rehabilitation, or simply by individuals interested in learning more about the links between diet and health.

Source: Imperial College London via EurekAlert