We all love to eat, but it’s no secret certain meals are much better for our bodies than others. Some ingredients, most often vegetables, are hailed as “super foods” that provide many nutrients and may help prevent illness. But how do researchers discover which foods defend us from diseases like cancer?

Usually, scientists rely on population studies to make associations between certain foods and cancer prevention. Participants track their diet in a log, which can lead to unreliable data — people forget things, and they sometimes alter their records to appear more favorably to researchers. A team of scientists from the Georgetown Lombardi Comprehensive Cancer Center in Washington say they’ve found a better way.

The researchers have developed a method that can efficiently assess the levels of specific food compounds in human urine — in other words, they can find a food journal in your pee. They say the tool could replace current methods used in population studies, making it easier to identify the effects of diet and particular foods on cancer. For the study, the team looked at cruciferous vegetables, including Brussels sprouts, cabbage, cauliflower, and watercress, which have previously shown protective benefits against lung cancer.

“We know these foods are beneficial to health, and the ten-minute method we developed, which can test for the presence of specific compounds linked to these vegetables, will help researchers quantify exactly how much of these molecules are being consumed,” said lead author Dr. Marcin Dyba of Georgetown Lombardi.

Dyba, who will present the findings at the annual meeting of the American Association for Cancer Research on April 18, explained that the urine test will also allow scientists to see which food compounds have the strongest association with cancer prevention. This could be tested in animal models, and if any molecules prove to be significantly protective, public health officials could strengthen dietary recommendations.

“We are very interested in understanding how and why the compounds work,” Dyba said. “You couldn’t do this work just using self-reported food logs.”

The test looks for specific members of the isothiocyanates (ITCs) family, along with other compounds found in cruciferous vegetables. Studies on animals and cells have shown that different ITCs have various anticancer properties, meaning they aren’t all equal in protecting against the disease, according to Dyba.

“We developed our test because there has been no way to find out which specific ITCs work best.”

Source: Chung F, Adams-Haduch J, Dyba M. A LC-MS/MS method to quantify specific dietary isothiocyanates in human urine for epidemiological studies. AACR Annual Meeting 2016. 2016.