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It’s International Sushi Day – ready for a bit of sushi science?

Here’s an interesting story…

Sushi – arty food that packs a scientific punch!
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A research group from the National Centre for Scientific Research (CNRS) in France, did a study on bacteria, and specifically their ability to produce enzymes to break down carbohydrates in their food. One of these enzymes, called porphyranase, specifically breaks down polysaccharide, a carbohydrate in the cell walls of Porphyra, an algae present in nori sheets, used to wrap sushi. Polysaccharide occurs very rarely in other marine plants.

By chance, they discovered that the enzyme porphyranase also occurs in the gut of a Japanese person. This was so unexpected that they pursued the discovery, by testing a group of Japanese people against a control group of Americans. It turned out that none of the Americans tested positive for the specific enzyme, while it occured in almost half of the Japanese test subjects.

Given that porphyranase is normally produced by the bacteria feeding on nori sheets, which is a main ingredient in the sushi-rich diet of the Japanese, they made the deduction that this “porphyranase producing ability” was genetically passed on from the bacteria in the food, to the bacteria in the intestines of the people.

The bacteria present in the intestines of the Japanese thus seem to have developed the ability to produce an enzyme that can digest seaweed, while the seaweed passes straight through the intestines of their American counterparts.

Source:  Nature, April 8, 2010

While this study is not conclusive, it is an interesting example of how the food we eat may affect us in very complex ways. Guess there’s truth in the saying “We are what we eat”!

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