Over the last 10 years, the microbial ecology of the gut has again become a major research area.
It is now generally accepted that the bacterial microflora which evolves from the first colonisation at birth in a previously sterile baby, constitutes an integral component of host defense and that this self-same flora appears to have changed in recent years.
The mucosal surface area of the adult human gastro-intestinal tract is up to 300 square metres, making it the largest body area interacting with the environment and containing a commensal bacterial load equivalent to ten times the number of cells in our body.
The colonisation of the intestines by a balanced microflora in the first one to two years of life is of major importance for the maturation of the immune system, as is clearly shown in studies of germ-free animals.
Probiotics and prebiotics
A probiotic is defined as a live microbial food ingredient that is beneficial to health, beyond its nutritional properties. Scientific and clinical research has focused mainly on members of the lactobacilli family.
Several strains of the lactobacilli family are facultative anaerobes (can live with or without oxygen) and are capable of colonising throughout the human gastrointestinal tract.
Only a small number of strains have been tested in properly controlled studies. These include L.acidophilus, L.casei, L reuteri. L.plantarum and L.rhamnosus.
A prebiotic, on the other hand, is a compound (indigestible starch) that promotes a microflora that is beneficial to health.
Prof. Bengt Björkstén MD, PhD
Prof.em. of Paediatrics and Allergy prevention
Karolinska Institute, Stockholm, Sweden