In an international, population-based study, scientists from Imperial College in London and a professor from the Feinberg School of Medicine identified chemicals in urine that highlight certain dietary elements associated with high blood pressure.

The paper, published online last month in the journal “Nature,” analyzed four chemicals in urine samples from 4,630 participants ages 40 to 59 from Japan, China, the United Kingdom and the United States. The chemicals, called metabolites, account for certain patterns of risks of high blood pressure and major heart diseases, said preventative medicine Prof. Jeremiah Stamler, who was formerly the first chairman of his department.

“We know that there are group differences in blood pressure,” he said. “Conditions of high blood pressure levels, known as prehypertension or the more elevated hypertension, vary between geographical areas like the north and south of China, as well as between dietary choices like getting protein from vegetables or from animal products.”

The paper is the most recent of several published works from scientists in the group, which has been studying the relation of dietary factors to blood pressure since the mid-1990s, said Stamler, the international principal investigator for the long-term research project.

“What we’re reaching for fundamentally are metabolic pathways by which dietary factors influence blood pressure,” he said. The compounds in urine, which he called “a mirror of the metabolism of the body,” can reveal the way food produces effects in the body.

The urine samples, gathered alongside dietary information and blood pressure measurements, were examined using nuclear magnetic resonance, a method of identifying “images” of biochemical compounds, he said.

The researchers looked at four metabolites in urine, three of which significantly related to blood pressure and helped account for the group differences. They found that higher levels of the chemical alanine, and lower amounts of formate and hippurate each correlated with higher blood pressure, Stamler said.

“We have taken four of a long list of metabolites in these first efforts,” he said, noting that the scientists still have to study the effects of many other metabolites, some of which have yet to be identified.