The promotion mechanism of prebiotics for probiotics: A review

Prebiotics and probiotics play a positive role in promoting human nutrition and health. Prebiotics are compounds that cannot be digested by the host, but can be used and fermented by probiotics, so as to promote the reproduction and metabolism of intestinal probiotics for the health of body. It has been confirmed that probiotics have clinical or health care functions in preventing or controlling intestinal, respiratory, and urogenital infections, allergic reaction, inflammatory bowel disease, irritable bowel syndrome and other aspects. However, there are few systematic summaries of these types, mechanisms of action and the promotion relationship between prebiotics and probiotic. Therefore, we summarized the various types of prebiotics and probiotics, their individual action mechanisms, and the mechanism of prebiotics promoting probiotics in the intestinal tract. It is hoped this review can provide new ideas for the application of prebiotics and probiotics in the future.

Juvenile toxicity study of Gossence™ (galactooligosaccharides) in Sprague Dawley rats

Gossence™ (galactooligosaccharide; GOS) is a prebiotics and used as one of the major constituents in infant milk formulas that act as a functional food. Gossence is manufactured by Tata Chemicals Ltd, India, through a patented process of biotransformation of lactose. A toxicology study in juvenile rats was carried out to assess the safety profile of Gossence intended for pediatric population. The objective of this study is to assess the potential systemic toxicity of Gossence when administered through gavage at dose levels of 1000, 2000, or 5000/3000 mg/kg/day (equivalent to 1347, 2694, and 6735/4041 mg/kg/day of GOS, respectively) to juvenile Sprague Dawley rats from postnatal day (PND) 4 to PND 52 (i.e. total 49 days of dosing period). A separate group of animals were treated with vehicle (purified Milli Q water) for a similar duration. The following parameters were evaluated during the study period: morbidity/mortality check, clinical signs, body weights, body weight changes, food consumption, functional observational battery, motor activity, postnatal developmental observations, hematology, clinical chemistry, urinalysis, organ weight, gross pathology, and histopathology. During dosing phase, the high-dose group, 5000 mg/kg/day, was reduced to 3000 mg/kg/day (equivalent to 4041 mg/kg/day dose of GOS) from day 16 (PND 19) onward, due to clinical signs of watery feces and yellow color stains at urogenital region and mortality in two animals on day 15 (PND 18) of the study. Time-weighted average dose for 5000 mg/kg/day was equivalent to 3600 mg/kg/day. No further deaths or clinical signs were noticed in animals at 3000 mg/kg/day from day 18 (PND 21) of dosing phase to until terminal euthanization. At the terminal euthanization, there were no test item-related gross changes observed in all surviving rats except for, an increased cecum size in some of the rats at 5000/3000 mg/kg/day, which correlated with the increased weights of cecum with contents during organ weight recording, but this had no correlating light microscopic changes during histological examination. The cecal enlargement was completely recovered following the 14-day recovery period. The no-observedadverse-effect level is 3000 mg/kg/day for Gossence, which is equivalent to 4041 mg/kg/day of GOS in both sexes.

Safety assessment of Gossence™ (galactooligosaccharides): Genotoxicity and general toxicity studies in Sprague Dawley rats

Galactooligosaccharides (GOS) used as prebiotics are one of the major constituents of the infant milk formulas. GOS (Gossence™) is produced by a patented process of biotransformation of lactose; hence toxicology studies were carried out to assess its safety. The objective of the present study was to evaluate the general and genetic toxicity of Gossence™. In 14-day and subchronic (90-day) oral toxicity studies in Sprague Dawley rats, daily administration of GOS at dose levels of 1000, 2000, or 5000 mg/kg (equivalent to 1347, 2694, and 6735 mg/kg/day of Gossence™, respectively) did not cause any mortality, or clinical signs, and changes in body weights, feed consumption, hematology, clinical chemistry, and urinalysis. In 90-day study, no changes in ophthalmological and neurological findings were observed. Significant increases in the cecum weights (with and/or without content) at dose levels of ≥2000 mg/kg were observed in both 14-day and 90-day studies. Based on the results of 90-day study, the no-observed-adverse-effect-level for GOS is 5000 mg/kg/day which is equivalent to 6735 mg Gossence™/kg/day. In the bacterial reverse mutation test, there was no significant increase in the mean numbers of revertants at the tested concentrations. Gossence™ was not mutagenic up to 5000 µg/plate. In chromosomal aberration test, there was no statistically significant increase in the number of percent aberrant metaphase for the Gossence™. Gossence™ is non-clastogenic (negative) in the in vitro chromosomal aberration test using human peripheral blood lymphocyte during short and prolonged treatment.

Infant formula with galacto-oligosaccharides (OM55N) stimulates the growth of indigenous bifidobacteria in healthy term infants

The objective of the study was to investigate whether an infant formula supplemented with galacto-oligosaccharides (GOS; OM55N) was able to stimulate the growth of indigenous bifidobacteria and to establish microbiota similar to that of breastfed infants. A randomised, double-blind, placebo-controlled trial was performed using 35 healthy term infants (31-54 days of age; 42±6 days) to determine whether infant formula with 0.3 g/dl GOS (OM55N) stimulated the growth of bifidobacteria in the infants’ guts. At the trial onset and 2 weeks after, the infants’ faecal samples were examined for microbiota composition (bacterial abundance and α-diversity) and faecal characteristics. Among the 35 infants, 5 were withdrawn and 8 were excluded from the final evaluation before breaking the blinding since the indigenous bifidobacteria were not detected at the trial onset. After 2 weeks, the abundance of Bifidobacteriaceae was significantly increased in the GOS feeding group compared to the control (+11.6±24.1% vs -3.9±13.0%; P=0.043). The Shannon index, which accounts for both abundance and evenness of the present species, was significantly decreased with GOS supplementation (-0.1±0.4 vs +0.4±0.4; P=0.014). Faecal characteristics such as pH and organic acids were similar in both groups, with no statistical differences. No adverse side effects related to the formula consumption were reported. Although the concentration of GOS was relatively low, the infant formula with GOS increased the abundance of bifidobacteria and resulted in a reduced α-diversity of the microbiota.