Eating a high-fibre diet could trigger changes in the immune system that protect against allergen-triggered asthma. Benjamin Marsland at the University Hospital in Lausanne in Switzerland found that mice fed a low-fibre diet had double the number of immune cells associated to asthmatic inflammation as those on a standard diet, after both groups were exposed to house mite dust.
Mice given fibre supplements on top of a standard diet showed a reduction in these immune cells – but only if the supplement was easily fermentable in the gut. This suggests that the protective effect can be traced back to gut bacteria.