Posted by: Hourglass PJ22 JAN 2014
Having researched the topic of dietary fibre fermentation in the gut more than 25 years ago, I was interested in a new Swiss study showing that fermented fibre might protect against asthma. The rationale is that gut bacteria ferment soluble fibre from foods such as vegetables, fruits, beans and lentils to produce short chain fatty acids.
The health benefits of these fatty acids in the large intestine have become better characterised since I conducted my research in that they are now known to have a potential role in helping to prevent bowel cancer. However, the findings of this new Swiss study suggest that these fatty acids may also have an influence in the lungs.
This was a preliminary study in which mice were put on to a highly fermentable fibre diet or a western diet with a lower proportion of fermentable fibre. When the mice were exposed to an extract of house dust mites, those with the low-fibre diet developed a stronger allergic reaction with much more mucus in the lungs than the mice with the standard diet.
The researchers found that the short-chain fatty acids produced by fermentation of the dietary fibre in the colon enter the bloodstream and influence the development of immune cells in the bone marrow. Attracted by the extract of house dust mites, these immune cells migrate into the lungs, where they eventually trigger a weaker allergic response than is the case if short chain fatty acids are not produced or are produced to a more limited extent.
Although this is a study in mice, the researchers say that the immune aspects they examined are indistinguishable between mice and humans. They plan to conduct studies in humans to see how fermentable fibres influence immunity and allergy.
In the meantime, the findings from this study suggest yet another good reason to eat plenty of fruit and vegetables.