It's almost logical that our urine contains traces of what we eat and drink. But an international team of researchers decided to learn more and has analyzed frozen urine samples from 4,630 people. These samples have been collected between 1997 and 1999 in China, Japan, the UK and the U.S. According to the researchers, this study shows the diversity of human metabolism across the globe. They can even predict where a person lives according to her or his urine. More importantly, this can lead to new ways to treat a variety of health problems, including obesity, diabetes or high blood pressure. But read more...
As the illustration above shows, people eat very differently in the countries studied, China, Japan, the UK and the U.S. This figure shows the macronutrient intake (in kcal) by country for the 2,336 men sampled. (Credit: Imperial College London, via Nature)
This research was led by Elaine Holmes, Professor of Chemical Biology at the Imperial College London (ICL), and one of her graduate students, Ruey Leng Loo. Additional help was provided by researchers from Belgium, China, Japan and the U.S.
Here is a quote from Professor Jeremy Nicholson, Chair In Biological Chemistry at ICL, about this research project. "'What our study really shows is how incredibly metabolically diverse people are around the world,' says Nicholson. 'British and American [metabolomes] are nearly identical. Japanese and Chinese people are totally different metabolically even though they are nearly identical genetically.' People who lived in Hawaii had metabolomes equally similar to those of people on the mainland United States and in Japan."
It's also worth to note the differences according where you live. "Interestingly, Nicholson says, the biggest difference between the 17 groups was between people from South China and everyone else. 'They have a very different and much broader range of diet,' he says. 'Very broadly speaking, the southern Chinese are the healthiest and the people in southern Texas are least healthy.'"
LiveScience also interviewed Nicholson for an article titled "Cultural Differences Found in Pee." Here is a quote. "'We know there's a huge difference in the diseases that different nations risk -- broadly speaking, the Japanese tend to die of strokes, the Chinese of heart attacks -- and we see those differences reflected in their urine,' he added. 'Of course they're different in terms of lifestyle -- the Japanese tend to eat more fish than the Chinese as a whole do -- but their gut bacteria are also very distinct as well.'"
Then, Nicholson explains how the gut microbes inside us get energy from what we eat. And he gives very surprising numbers -- at least for me. "'In your guts, you have about 1.5 kilograms (3.3 pounds) of 1,000 different species of bacteria,' Nicholson explained. 'If you include all the genes from bacteria along with your own, only about 1 to 2 percent of the genes in your body are human, with the rest from the gut microbes. And what bacteria you have can be quite different from person to person.'"
This research work is featured on the Nature website as an advance online publication dated April 20, 2008. It carries the title "Human metabolic phenotype diversity and its association with diet and blood pressure." Here is a link to the abstract. The figure above has been extracted from some supplementary information available from Nature.
Finally, it's interesting to note that Elaine Holmes, who is less vocal than Nicholson, also co-signed an article on the same subject published in the International Journal of Epidemiology, "High-throughput 1H NMR-based metabolic analysis of human serum and urine for large-scale epidemiological studies: validation study" (Volume 37, Supplement 1, Pages i31-i40, April 2008). Here is a link to the abstract.
Sources: Emma Marris, Nature News, April 18, 2008; Charles Q. Choi, Special to LiveScience, April 20, 2008; and various websites
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