The latest research from Sahlgrenska Academy clarify the mechanisms for how fiber contributes to colonic health . Meanwhile, many people in contemporary society appear to be heading in a different direction altogether. The study was published in the  Cell Host & Microbe

Dietary fiber is a key source for their nutrition. Thus the quantity of fiber in your diet influences your weight, blood glucose level and sensitivity to insulin is well-established. Scientists at Sahlgranska Academy shows that colonic health is also affected.    

"Average fiber has declined drastically in developed countries over the past few decades," Fredrik Bäckhed, Professor of Molecular Medicine, says. I have studied the role of gut bacteria in metabolic disorders.

Various kinds of fiber are found in fruit, legumes, vegetables and whole grain products. Insufficient fiber combined with a high-fat, high-carbohydrate diet is associated with a greater risk of inflammatory bowel disease, weight gain and diabetes.

Mice in the current study were put on a low-fiber diet. They developed defects in the inner colonic mucus layer after only three days characterized by increased bacterial penetrability, a potential risk for inflammatory bowel disease and other disorders.

"Our results demonstrate that the inner mucus layer separate gut bacteria from the body cells," Gunnar C. Hansson, Professor of Medical and Physiological Chemistry and director of the study, says. "We clearly illustrated the rapid, process by which the mucus layer responds to dietary modifications and subsequent bacterial changes."

In a second experiment, the mice fed fiber-depleted diet received a transplant of gut bacteria from a fed animal and regained some of the lost protective effect .

A dietary supplement of friendly bifidobacteria stimulated growth of the mucus layer but did not prevent bacteria in the gut microbiota from approaching the body's cells. A supplement of inulin, a type of dietary fiber, addressed the latter problem but not the former.

"Low-fiber diets alter bacterial composition and influence what they produce," Professor Hansson says. "The result can be greater than that of the body cells."

The researchers believe that fiber supplements as a method of treatment need to be investigated further. Simply enriching food with refined fiber is not recommended before more has been learned about its complex interplay with food, bacteria and the body's cells.