How bowl of bran beats off bugs

EATING plenty of fibre is not only good for your heart – it also protects against infection, scientists have found.

A bit of roughage, whether a stalk of broccoli, bowl of bran flakes or a slice of wholemeal bread, maintains the layer of mucus which is the gut’s first line of defence against bacteria.

The layer helps keep out bugs such as E.coli which can cause food poisoning. But it relies on fibre to function because, when our digestive microbes do not have fibre to eat, they are now believed to start feasting on the protective barrier instead to the point where invading bugs can get in.

Scientists at the University of Michigan put human gut bacteria into mice and discovered that those deprived of fibre were more easily infected with E.coli. It is another reason to eat your greens, porridge oats, lentils and nuts, with fibre already known to cut the risk of heart disease, stroke and bowel cancer. However most Britons eat less than half the 30g we should get a day.

Dr Eric Martens, an associate professor at the University of Michigan’s Medical School, said: ‘While this work was in mice, the takehome message from it for humans amplifies everything that doctors and nutritionists have been telling us for decades: Eat a lot of fibre from diverse natural sources.

‘Your diet directly influences your microbiota (bacteria in the body), and from there it may influence the status of your gut’s mucus layer and tendency toward disease.’ For the study, published in the journal Cell, mice with no gut microbes of their own received a transplant of 14 bacteria that normally grow in the human gut. Some mice were infected with a bacterial strain with similar effects to E.coli on humans including inflammation and diarrhoea.

Those given a diet made up of 15 per cent fibre from plants and grains did not see the infection take full hold because their protective mucus layer stayed thick. But a few days without fibre saw the microbes start to feast on the mucus. These mice became more infected by dangerous bacteria.

Dr Martens said: ‘The lesson from studying the interaction of fibre, gut microbes and the intestinal barrier system is that if you don’t feed them, they can eat you.’