ABSTRACT
Growth and health are ultimately dependent on the efficient assimilation of nutrients from the small intestine. To achieve maximum efficiency in food conversion it is not only necessary for the diet to be of high nutritional quality, but the optimal functioning of the digestive tract is also essential. However, as food is digested and absorbed in the presence of bacteria, this is seldom attained. Although the main digestive/ absorptive compartment of the gastrointestinal tract, the small intestine, in healthy individuals is usually regarded as essentially free from coliforms and other potentially harmful bacteria, it is far from being germfree. Moreover, it is clear that damage to the epithelial surface or simply even a change of diet may lead to speedy proliferative changes in the bacterial content of the small intestine and, therefore, gastrointestinal upsets can occur under conditions of strict hygiene (Savage, 1987; Shimizu and Terashima, 1982).
