Modern diets change human gut
Scientists have found that humans who live in towns and cities are less likely to be able to digest fruit and vegetables properly. A recent study says that people’s ability to process the plants they eat is all down to the microbes (tiny living things) in the gut, but modern diets are changing those microbes.
Plants, such as fruits and vegetables, contain a tough material called cellulose. For a long time, scientists didn’t think humans could digest cellulose in the same way that cows and sheep can. However, back in 2003, scientists found gut microbes in humans that can break down cellulose. This new study looked at these microbes in detail.
A team from Ben-Gurion University of the Negev, in Israel, studied human poo and identified a microbe called Ruminococcus, which can break down cellulose. This suggests humans have more in common with grass-munching cows than scientists thought, because their guts are home to this kind of microbe too. It’s thought that Ruminococcus spread from animals to humans thousands of years ago, when people lived more closely with animals. The team compared poo from modern humans with poo from early humans, and found that Ruminococcus was far more common in people who lived in the countryside in ancient times. It is scarcer in modern humans who live in more urbanised (town-like) places.
The scientists think that as societies have changed, diets changed too. Nowadays people tend to eat more processed food than in the past. “Processed” food is food that has been altered in some way, such as being cooked or having salt or sugar added to it. Scientists say that by eating more processed foods, people may be losing the microbes that a healthy gut needs to break down the plants they eat. It is not yet clear what this could mean but the study is a big step for scientists trying to understand gut microbes and how they affect our health.