Development of five metabolic activities associated with the intestinal microflora of healthy infants.

The establishment of a functionally active intestinal flora was followed in 17 healthy Swedish children from birth up to 6 months of age. Utilizing gas chromatography, spectrophotometry, and gel electrophoresis, feces were analyzed on certain biochemical markers that reflect the action of the intestinal flora in vivo. The establishment of the following five flora-related functions was investigated: production of short chain fatty acids (SCFAs), degradation of mucin, conversion of bilirubin to urobilinogen and of cholesterol to coprostanol, and inactivation of fecal tryptic activity (FTA). Production of SCFAs was the first function to be established, followed by bilirubin conversion and mucin degradation. No child showed conversion of cholesterol. The values of FTA were lower than in adults. This study indicates that the establishment of a functionally active flora is a slow process and that some functions are almost fully established before other functions have started to develop. Environmental factors, such as the diet, seem to be of importance. In general, the functions seem to develop slower in those children receiving breast milk exclusively than in those receiving formula supplements.