Prebiotics: better for us than we thought
ingredients, but recent research in the US has shown that, despite
our extensive knowledge base, we have just scratched the surface.
Prebiotics are becoming increasingly popular health ingredients as a result of their effects on the population and metabolic characteristics of the gastrointestinal bacteria, their ability to modulate enteric and systemic immune functions, and impart resistance to colorectal cancer-inducing carcinogens in laboratory animals. But less is known about protection from other challenges to our health.
Researchers from the Department of Biological Sciences and College of Veterinary Medicine, Mississippi State University, recently investigated other possible benefits.
The scientists fed mice of a particular strain one of three diets for six weeks. The diets consisted of a control diet with 100 g/kg cellulose or one of two experimental diets with the cellulose replaced entirely by the non-digestible oligosaccharides oligofructose and inulin.
Twenty-five animals from each diet were challenged with a disease promoter. Researchers found that the incidences of aberrant crypt foci in the distal colon after exposure to a promoter of colorectal cancer for mice fed inulin (53 per cent) and oligofructose (54 per cent) were lower than in control mice (76 per cent), but the fructans did not reduce the incidence of lung tumours after injection of tumour cells.
Mice fed the diets with fructans had 50 per cent lower densities of the enteric pathogen Candida albicans in the small intestine.
A systemic infection with with Listeria monocytogenes caused nearly 30 per cent mortality among control mice, but none of the mice fed inulin died. Mortality was higher for the systemic infection of Salmonella typhimurium, but fewer of the mice fed inulin died, with mice fed oligofructose again intermediate.
The scientists did not elucidate on the mechanistic basis for the increased resistance provided by dietary non-digestible oligosaccharides but the findings revealed enhanced immune functions in response to changes in the composition and metabolic characteristics of the bacteria resident in the gastrointestinal tract.
Full findings are published in the March issue of the Journal of Nutrition.
