Mixture Of Galacto-oligosaccharides Research Articles

A double-blind, placebo-controlled, randomized human study assessing the capacity of a novel galacto-oligosaccharide mixture in reducing travellers' diarrhoea

Prebiotics have attracted interest for their ability to positively affect the colonic microbiota composition, thus increasing resistance to infection and diarrhoeal disease. This study assessed the effectiveness of a prebiotic galacto-oligosaccharide mixture (B-GOS) on the severity and/or incidence of travellers' diarrhoea (TD) in healthy subjects. The study was a placebo-controlled, randomized, double blind of parallel design in 159 healthy volunteers, who travelled for minimum of 2 weeks to a country of low or high risk for TD. The investigational product was the B-GOS and the placebo was maltodextrin. Volunteers were randomized into groups with an equal probability of receiving either the prebiotic or placebo. The protocol comprised of a 1 week pre-holiday period recording bowel habit, while receiving intervention and the holiday period. Bowel habit included the number of bowel movements and average consistency of the stools as well as occurrence of abdominal discomfort, flatulence, bloating or vomiting. A clinical report was completed in the case of diarrhoeal incidence. A post-study questionnaire was also completed by all subjects on their return. Results showed significant differences between the B-GOS and the placebo group in the incidence (P<0.05) and duration (P<0.05) of TD. Similar findings occurred on abdominal pain (P<0.05) and the overall quality of life assessment (P<0.05). Consumption of the tested galacto-oligosaccharide mixture showed significant potential in preventing the incidence and symptoms of TD.

Separation of galacto-oligosaccharides mixture by nanofiltration

Four commercial 1812 spiral wound nanofiltration membranes were firstly applied to examine the separation performance of sugar solutions in total recycle mode of operation. Membrane NF-3 (supplied by Sepro Co. (USA)) with molecular weight cut-off of 800–1000 Da was selected for separation of a commercial galactose-oligosaccharide (GOS) mixture with low content of oligosaccharides in constant volume diafiltration (CVD) process at 50 °C and 6 bar pressure. The choosing of membrane and operation conditions for CVD process was based on a compromise between the permeate fluxes and apparent rejections of the sugar solution. In CVD course, the concentration of various sugars and the relationship between the yield and purity of oligosaccharides predicted well with mathematical models for the following situation: when the volume of every removing batch of permeate is equal to the volume of tank, the increased rate of sugar rejections is less than 8% and the decreased rate of tank concentrations is less than 15%. 90.5% monosaccharide and 52.5% lactose in the mixture were removed with NF-3 membrane in this study, and the oligosaccharides purity of 54.5% was achieved (1.5 times of the raw material), obtaining oligosaccharides yield of 70.0%.

A specific mixture of short‐chain galacto‐oligosaccharides and long‐chain fructo‐oligosaccharides induces a beneficial immunoglobulin profile in infants at high risk for allergy

It has been suggested that human breast milk oligosaccharides play a role in the development of the immune system in infants, and may consequently inhibit the onset of allergy. A specific prebiotic mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides (GOS/FOS) has been shown to reduce the incidence of atopic dermatitis (AD) at 6 months of age in infants at risk for allergy. This study was aimed to analyze the effect of GOS/FOS on the immune response in these infants. In a double-blind randomized placebo-controlled study, infants received a hypoallergenic whey formula with either 8 g/l GOS/FOS in a 9 : 1 ratio (IMMUNOFORTIS) or 8 g/l maltodextrine (placebo) for 6 months. At 3 months of age, children were vaccinated with Hexavac against a.o. diphteria, tetanus, polio (DTP). At 6 months of age, plasma samples were collected from 84 infants (verum group n = 41, placebo group n = 43). Levels of total immunoglobulins (Ig) and of cow's milk protein (CMP-) and DTP-specific Ig were measured. GOS/FOS supplementation led to a significant reduction in the plasma level of total IgE, IgG1, IgG2 and IgG3, whereas no effect on IgG4 was observed. CMP-specific IgG1 was significantly decreased. DTP-specific Ig levels were not affected. This study shows that GOS/FOS supplementation induces a beneficial antibody profile. GOS/FOS reduces the total Ig response and modulates the immune response towards CMP, while leaving the response to vaccination intact. This suggests that oral GOS/FOS supplementation is a safe method to restrain the atopic march.

A specific mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides induced an anti-allergic Ig profile in infants at risk for allergy

A specific mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides induced an anti-allergic Ig profile in infants at risk for allergy

Prebiotic evaluation of a novel galactooligosaccharide mixture produced by the enzymatic activity of Bifidobacterium bifidum NCIMB 41171, in healthy humans: a randomized, double-blind, crossover, placebo-controlled intervention study

Background: Galactooligosaccharides are selectively fermented by the beneficial member of the colonic microflora contributing to the health of the host.Objective: We assessed the prebiotic potential of a novel galactooligosaccharide produced through the action of β-galactosidases, originating from a probiotic Bifidobacterium bifidum strain, against a galactooligosaccharide produced through the action of an industrial β-galactosidase and a placebo.Design: Fifty-nine healthy human volunteers participated in this study. Initially, the effect of the matrix on the prebiotic properties of a commercially available galactooligosaccharide (7 g/d) was assessed during 7-d treatment periods with a 7-d washout period in between. During the second phase, 30 volunteers were assigned to a sequence of treatments (7 d) differing in the amount of the novel galactooligosaccharide (0, 3.6, or 7 g/d). Stools were recovered before and after each intervention, and bacteria numbers were determined by fluorescent in situ hybridization.Results: Addition of the novel galactooligosaccharide mixture significantly increased the bifidobacterial population ratio compared with the placebo (P < 0.05), whereas 7 g/d of the novel galactooligosaccharide significantly increased the bifidobacterial ratio compared with the commercial galactooligosaccharide (P < 0.05). Moreover, a significant relation (P < 0.001) between the bifidobacteria proportion and the novel galactooligosaccharide dose (0, 3.6, and 7 g/d) was observed. This relation was similar to the effect of the novel galactooligosaccharide on the prebiotic index of each dose.Conclusions: This study showed that galactooligosaccharide mixtures produced with different β-galactosidases show different prebiotic properties and that, by using enzymes originating from bifidobacterial species, an increase in the bifidogenic properties of the prebiotic product is achievable.

Production of lactose-free galacto-oligosaccharide mixtures: comparison of two cellobiose dehydrogenases for the selective oxidation of lactose to lactobionic acid

Galacto-oligosaccharides, complex mixtures of various sugars, are produced by transgalactosylation from lactose using β-galactosidase and are of great interest for food and feed applications because of their prebiotic properties. Most galacto-oligosaccharide preparations currently available in the market contain a significant amount of monosaccharides and lactose. The mixture of galacto-oligosaccharides (GalOS) in this study produced from lactose using recombinant β-galactosidase from Lactobacillus reuteri contains 48% monosaccharides, 26.5% lactose and 25.5% GalOS. To remove efficiently both monosaccharides and lactose from this GalOS mixture containing significant amounts of prebiotic non-lactose disaccharides, a biocatalytic approach coupled with subsequent chromatographic steps was used. Lactose was first oxidised to lactobionic acid using fungal cellobiose dehydrogenases, and then lactobionic acid and monosaccharides were removed by ion-exchange and size-exclusion chromatography. Two different cellobiose dehydrogenases (CDH), originating from Sclerotium rolfsii and Myriococcum thermophilum, were compared with respect to their applicability for this process. CDH from S. rolfsii showed higher specificity for the substrate lactose, and only few other components of the GalOS mixture were oxidised during prolonged incubation. Since these sugars were only converted once lactose oxidation was almost complete, careful control of the CDH-catalysed reaction will significantly reduce the undesired oxidation, and hence subsequent removal, of any GalOS components. Removal of ions and monosaccharides by the chromatographic steps gave an essentially pure GalOS product, containing less than 0.3% lactose and monosaccharides, in a yield of 60.3%.

Prebiotic oligosaccharides and the enterohepatic circulation of bile salts in rats

Human milk contains prebiotic oligosaccharides, which stimulate the growth of intestinal bifidobacteria and lactobacilli. It is unclear whether the prebiotic capacity of human milk contributes to the larger bile salt pool size and the more efficient fat absorption in infants fed human milk compared with formula. We determined the effect of prebiotic oligosaccharides on bile salt metabolism in rats. Rats were fed a control diet or an isocaloric diet containing a mixture of galactooligosaccharides (GOS), long-chain fructooligosaccharides (lcFOS), and acidified oligosaccharides (AOS) for 3 wk. We determined synthesis rate, pool size, and fractional turnover rate (FTR) of the primary bile salt cholate by using stable isotope dilution methodology. We quantified bile flow and biliary bile salt secretion rates through bile cannulation. Prebiotic intervention resulted in significant changes in fecal and colonic flora: the proportion of lactobacilli increased 344% (P < 0.01) in colon content and 139% (P < 0.01) in feces compared with the control group. The number of bifidobacteria also increased 366% (P < 0.01) in colon content and 282% in feces after the prebiotic treatment. Furthermore, pH in both colon and feces decreased significantly with 1.0 and 0.5 pH point, respectively. However, despite this alteration of intestinal bacterial flora, no significant effect on relevant parameters of bile salt metabolism and cholate kinetics was found. The present data in rats do not support the hypothesis that prebiotics naturally present in human milk contribute to a larger bile salt pool size or altered bile salt pool kinetics.

Dietary supplementation of neutral and acidic oligosaccharides enhances Th1‐dependent vaccination responses in mice

Immunomodulatory effects of oligosaccharide preparations that resemble chemical and functional aspects of human milk oligosaccharides (HMOS) were studied for the development of new concepts in infant nutrition. A dose range of 1-5% (w/w) dietary pectin-derived acidic oligosaccharides (AOS) was tested in a murine influenza vaccination model. In addition, combinations of AOS and a 9:1 mixture of galacto-oligosaccharides and long-chain fructo-oligosaccharides (GOS/FOS) were tested at a fixed total dietary dose of 2% (w/w). It was found that AOS significantly enhanced vaccine-specific delayed-type hypersensitivity (DTH) responses in a dose-dependent manner. This was accompanied by a reduction in T-helper2 (Th2) cytokine production by splenocytes in vitro. Overall, this indicates that the systemic immune response to the vaccine was Th1-skewed by the dietary intervention. Combinations of GOS/FOS and AOS were more effective in enhancing DTH responses than either of the oligosaccharides alone, suggesting interaction effects between these agents. Similar to effects in infants, supplementation of the murine diets with GOS/FOS and combinations of GOS/FOS and AOS for 6-wk enhanced the proportion of fecal bifidobacteria and lactobacilli, but AOS alone did not. In conclusion, these data indicate that GOS/FOS and AOS enhance systemic Th1-dependent immune responses in a murine vaccination model. As Th1-responses are weak in early life in humans, this might suggest that application of these oligosaccharides in infant formulas will be beneficial for the development of the infant's immune system.

Galacto-oligosaccharides and bowel function

Constipation is a common problem and its prevalence increases with age. Severe constipation requires treatment with laxatives, but nutritional therapy, especially increased dietary fibre intake, is recommended primarily for the prevention and treatment of mild constipation. One alternative may be the use of oligosaccharides, which act as soluble fibre and have a bifidogenic effect. Galacto-oligosaccharides (GOS) resembling oligosaccharides occurring naturally in human milk can be produced from lactose. Several clinical studies reviewed in this paper have shown that the use of GOS (5–15g per day) may relieve the symptoms of constipation in adults and elderly people. In infants, the supplementation of formula with a mixture of GOS and fructo-oligosaccharides can modulate bowel function and stool characters in the same direction as does breast-feeding. Gastrointestinal symptoms may occur as side-effects of oligosaccharides, but 12g GOS per day or less is usually well tolerated.

Oligosaccharides from Milk1,

Feeding infants breast milk of healthy mothers is associated with a lower incidence of infectious and allergic diseases. Although this effect is of multifactorial origin, it is widely accepted that the entire intestinal flora of breast-fed infants provides antiinfective properties and is an important stimulating factor for the postnatal development of the immune system. The effect of human milk on the postnatal development of the intestinal flora cannot be attributed to a single ingredient. It is generally accepted, however, that human milk oligosaccharides play a key role in this matter. Apart from their prebiotic effects, there is also evidence that human milk oligosaccharides act as receptor analogs to inhibit the adhesion of pathogens on the epithelial surface and interact directly with immune cells. Because of their complexity, oligosaccharides with structures identical to human milk oligosaccharides are not yet available as dietary ingredients. In the current search for alternatives, non-milk-derived oligosaccharides have gained much attention. As 1 example, a mixture of neutral galacto-oligosaccharides and long chain fructo-oligosaccharides have been identified as effective prebiotic ingredients during infancy. Furthermore, another class of oligosaccharides with a potential physiological benefit could be those found in animal milks. Most of the oligosaccharides detected in domestic animal milks have some structural features in common with human milk oligosaccharides. One important fact is the occurrence of sialic acids such as N-acetylneuraminic acids. However, total amounts and individual structures are still different from those in human milk oligosaccharides. Although these structural similarities between animal milk and human milk oligosaccharides are promising, further studies are needed to proove the equivalence of their function.

Impact of prebiotics on human health

It is becoming clear that intestinal microlora plays an important role in the development of local and systemic immune response. Nutritional ingredients have been added to infant formula in an attempt to make its composition similar to that of human milk. The effects of these modifications have been observed in the composition of intestinal microlora. Prebiotics are non-digestible foods able to selectively stimulate the growth/activity of a limited number of colonic bacteria. A mixture of galacto-oligosaccharides and fructo-oligosaccharides (GOS/FOS) induces an increase in Bifidobacteria, similar to that of breast-fed infants. What is less clear is whether the modifications of intestinal microlora obtained by functional foods are associated with clinically measurable effects. Preliminary indirect data suggest that increasing the load of Bifidobacteria and Lactobacilli may protect from infections and allergies and this effect may persists beyond infancy. The emerging concept is that early nutritional intervention may be effective in modifying the intestinal microlora composition in a phase in which microbiological imprinting may drive immunological imprinting thereby producing clinical effects. Further investigations and well designed randomised clinical trials are needed to demonstrate the potential beneficial effects and to exclude the potential side effects.

Effect of feed additives on ruminal methanogenesis and anaerobic fermentation of manure in cows and steers

The inhibition of enteric methanogenesis using feed additives and anaerobic fermentation of animal manure to renewable energy is beneficial for the environment and to the producers. Two experiments were conducted using 4 steers and 4 cows in double 4 × 4 Latin square designs to investigate the potential effect of various feed additives on enteric and manure derived methanogenesis. In experiment 1, steers were offered high concentrate diets (80% concentrate and 20% hay) ad libitum with or without monensin, galacto-oligosaccharides (GOS) or l-cysteine. In experiment 2, cows were offered a diet (35% oat straw, 35% alfalfa hay cubes and 30% concentrates) at 76 g/kg BW 0.75 daily with or without GOS, yeast culture (YC) or a mixture of GOS and YC. Steers that received monensin and GOS-containing diets had lower enteric CH 4 missions. Digesters at 55 °C that were filled with manure from steers fed on monensin containing diets delayed in the initial CH 4 production. However, after 40 days, CH 4 production increased in digesters filled with monensin-containing manure. Monensin is a strong inhibitor of enteric methanogenesis, but has a negative influence on biogas energy production at short retention times.

Effects of infant formula containing a mixture of galacto- and fructo-oligosaccharides or viableBifidobacterium animalison the intestinal microflora during the first 4 months of life

Adding prebiotics or probiotics to infant formula to improve the intestinal flora of formula-fed infants is considered to be a major innovation. Several companies have brought relevant formulations onto the market. However, comparative data on the effects of pre- and probiotics on the intestinal microflora of infants are not available. The present study aimed to compare the effects of infant formula containing a mixture of galacto- and fructo-oligosaccharides or viable Bifidobacterium animalis on the composition and metabolic activity of the intestinal microflora. Before birth, infants were randomised and double blindly allocated to one of three formulas. The prebiotic (GOS/FOS) group (n 19) received regular infant formula supplemented with a mixture of galacto-oligosaccharides and fructo-oligosaccharides (6 g/l). The probiotic (Bb-12) group (n 19) received the same formula supplemented with 6.0x10(10) viable cells of B. animalis per litre. The standard group (n 19) received non-supplemented regular formula. A group of sixty-three breast-fed infants was included as a reference group. Faecal samples were taken at postnatal day 5 and 10, and week 4, 8, 12 and 16. Compared with the groups fed Bb-12 and standard formula, the GOS/FOS formula group showed higher faecal acetate ratio (69.7 % (sem 2.7), 69.9 % (sem 3.9) and 82.2 % (sem 5.3); P<0.05) and lactate concentration (11.3 (sem 7.9), 3.1 (sem 2.3) and 34.7 (sem 10.7) mmol/kg faeces) and lower pH (6.6 (sem 0.2), 7.1 (sem 0.2) and 5.6 (sem 0.2); P<0.05) at 16 weeks. Differences in percentage of bifidobacteria between the GOS/FOS (59.2 % (sem 7.7)), Bb-12 (52.7 % (sem 8.0)) and the standard (51.8 % (sem 6.4)) groups were not statistically significant at 16 weeks. Feeding infants GOS/FOS formula resulted in a similar effect on metabolic activity of the flora as in breast-fed infants. In the Bb-12 group, composition and metabolic activity of the flora were more similar to those of the standard group.

Reproducing the bifidogenic effect of human milk in formula‐fed infants: Why and how?

Awareness of the key role of the intestinal microflora in the generation of the immunophysiological regulation and in the defence against pathogenic agents has attracted our interest in ways of manipulating the microbiota to improve health. Dietary modulation of the intestinal microflora is today one of the main topics of interest in the nutritional sciences. Performing this modulation in the neonatal or early infancy period, when immunological programming takes place, is a relatively new concept. Fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) are prebiotics whose bifidogenic activity has been proven in adults. However, only recently have they been combined in infant formulas to reproduce the prebiotic effect of human milk oligosaccharides. In two consecutive trials, it has been demonstrated that supplementation of infant formulas with a mixture of GOS and FOS modified the fecal flora of term and preterm infants, stimulating the growth of Bifidobacteria. In the trial with term infants, the bifidogenic effect of the prebiotic mixture was dose dependent and there was also a significant increase in the number of Lactobacilli in the supplemented group. These findings offer a promising horizon for the early prevention of allergy and infections in infants.

Galacto-oligosaccharides and long-chain fructo-oligosaccharides as prebiotics in infant formulas: A review

The present review summarizes clinical and experimental data concerning the possible effects of a prebiotic mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides. The results from several studies, made up of over 400 preterm and term infants, clearly demonstrate that the prebiotic mixture under examination specifically stimulates the growth of bifidobacteria and lactobacilli and reduces the growth of pathogens. As a consequence of the changed intestinal flora by the dietary galacto-oligosaccharides and fructo-oligosaccharides, the faecal pH values and the short-chain fatty acid pattern were similar to those found in breastfed infants. In addition, the stool consistency was the same as in breastfed infants. In vitro experiments have demonstrated that the specific short-chain fatty acid pattern, at a pH similar to that found in faecal samples of breastfed infants, reduces the growth of pathogens in a dose-dependent manner but does not influence the growth of bifidobacteria and lactobacilli. In an animal vaccination model, the prebiotic mixture improved the response to vaccination. In an allergy model (sensitization by ovalbumin), the allergic reaction was reduced by the prebiotic mixture. The data obtained from animal experiments are in agreement with preliminary data from clinical trials which indicate a reduced allergic response (reduced plasma IgE/IgG4 ratio) and reduced episodes of upper airway infection during the first year of life.Experimental evidence demonstrates that the prebiotic mixture employed in these studies modulates the intestinal flora and modulates the immune system as human milk does. There are sufficient experimental data to put forward the hypothesis that substances like the prebiotic mixture under study will substantially contribute to the improvement of the protective properties of infant formulas.

Galacto‐oligosaccharides and long‐chain fructo‐oligosaccharides as prebiotics in infant formulas: A review

The present review summarizes clinical and experimental data concerning the possible effects of a prebiotic mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides. The results from several studies, made up of over 400 preterm and term infants, clearly demonstrate that the prebiotic mixture under examination specifically stimulates the growth of bifidobacteria and lactobacilli and reduces the growth of pathogens. As a consequence of the changed intestinal flora by the dietary galacto-oligosaccharides and fructo-oligosaccharides, the faecal pH values and the short-chain fatty acid pattern were similar to those found in breastfed infants. In addition, the stool consistency was the same as in breastfed infants. In vitro experiments have demonstrated that the specific short-chain fatty acid pattern, at a pH similar to that found in faecal samples of breastfed infants, reduces the growth of pathogens in a dose-dependent manner but does not influence the growth of bifidobacteria and lactobacilli. In an animal vaccination model, the prebiotic mixture improved the response to vaccination. In an allergy model (sensitization by ovalbumin), the allergic reaction was reduced by the prebiotic mixture. The data obtained from animal experiments are in agreement with preliminary data from clinical trials which indicate a reduced allergic response (reduced plasma IgE/IgG4 ratio) and reduced episodes of upper airway infection during the first year of life. Experimental evidence demonstrates that the prebiotic mixture employed in these studies modulates the intestinal flora and modulates the immune system as human milk does. There are sufficient experimental data to put forward the hypothesis that substances like the prebiotic mixture under study will substantially contribute to the improvement of the protective properties of infant formulas.

A Novel Galactooligosaccharide Mixture Increases the Bifidobacterial Population Numbers in a Continuous In Vitro Fermentation System and in the Proximal Colonic Contents of Pigs In Vivo

Prebiotics are nondigestible food ingredients that encourage proliferation of selected groups of the colonic microflora, thereby altering the composition toward a more beneficial community. In the present study, the prebiotic potential of a novel galactooligosaccharide (GOS) mixture, produced by the activity of galactosyltransferases from Bifidobacterium bifidum 41171 on lactose, was assessed in vitro and in a parallel continuous randomized pig trial. In situ fluorescent hybridization with 16S rRNA-targeted probes was used to investigate changes in total bacteria, bifidobacteria, lactobacilli, bacteroides, and Clostridium histolyticum group in response to supplementing the novel GOS mixture. In a 3-stage continuous culture system, the bifidobacterial numbers for the first 2 vessels, which represented the proximal and traverse colon, increased (P < 0.05) after the addition of the oligosaccharide mixture. In addition, the oligosaccharide mixture strongly inhibited the attachment of enterohepatic Escherichia coli (P < 0.01) and Salmonella enterica serotype Typhimurium (P < 0.01) to HT29 cells. Addition of the novel mixture at 4% (wt:wt) to a commercial diet increased the density of bifidobacteria (P < 0.001) and the acetate concentration (P < 0.001), and decreased the pH (P < 0.001) compared with the control diet and the control diet supplemented with inulin, suggesting a great prebiotic potential for the novel oligosaccharide mixture.

Application of prebiotics in infant foods

The rationale for supplementing an infant formula with prebiotics is to obtain a bifidogenic effect and the implied advantages of a 'breast-fed-like' flora. So far, the bifidogenic effect of oligofructose and inulin has been demonstrated in animals and in adults, of oligofructose in infants and toddlers and of a long-chain inulin (10 %) and galactooligosaccharide (90 %) mixture in term and preterm infants. The addition of prebiotics to infant formula softens stools but other putative effects remain to be demonstrated. Studies published post marketing show that infants fed a long-chain inulin/galactooligosaccharide mixture (0.8 g/dl) in formula grow normally and have no side-effects. The addition of the same mixture at a concentration of 0.8 g/dl to infant formula was therefore recognized as safe by the European Commission in 2001 but follow-up studies were recommended. It is thought that a bifidogenic effect is beneficial for the infant host. The rising incidence in allergy during the first year of life may justify the attempts to modulate the infant's flora. Comfort issues should not be confused with morbidity and are likely to be multifactorial. The functional effects of prebiotics on infant health need further study in controlled intervention trials.

Synthesis of prebiotic galactooligosaccharides using whole cells of a novel strain, Bifidobacterium bifidum NCIMB 41171

A novel strain of Bifidobacterium bifidum NCIMB 41171, isolated from a faecal sample from a healthy human volunteer and able to express beta-galactosidase activity, was used in synthesis reactions for the production of galactooligosaccharide from lactose. The beta-galactosidase activity of whole bifidobacterial cells showed an optimum activity at pH 6.8-7.0 and 40 degrees C. The transgalactosylation activity of the B. bifidum cells from 50% (w/w) lactose resulted in a galactooligosaccharide mixture (20% w/w) comprising (w/w): 25% disaccharides, 35% trisaccharides, 25% tetrasaccharides and 15% pentasaccharides. Using different initial lactose concentrations, the conversion rate to galactooligosaccharides was maximum (35%) when 55% (w/w) lactose was used. In fermentation experiments, B. bifidum showed an increased preference towards the produced galactooligosaccharide mixture, displaying higher growth rate and short-chain fatty acid production when compared with commercially available oligosaccharides.

Dietary Galacto-Oligosaccharides Mixture Can Suppress Serum Phenol and p-Cresol Levels in Rats Fed Tyrosine Diet

Phenols (phenol and p-cresol) are amino acid metabolites produced by intestinal bacteria. Some reports have demonstrated that the accumulation of phenols in the serum has toxic effects in renal failure patients. In this study, we found that phenols accumulated in the serum of rats given a tyrosine diet, and that dietary intake of a galacto-oligosaccharide mixture (GOS) suppressed the accumulation of phenols in serum. Rats were fed a basal diet, tyrosine diet (basal diet with 2.5% tyrosine) or GOS diet (tyrosine diet with 5% GOS) for 2 wk. The concentrations of phenols in the feces, cecal contents, serum and urine were determined. Concentrations of phenols in the serum, cecal contents and feces from rats fed the tyrosine diet were significantly higher than those in rats fed the basal diet. The concentrations of phenols in feces, cecal contents and serum, and urinary excretion in the GOS diet group were significantly lower than those in the tyrosine diet group. The pH of cecal contents was decreased by GOS intake. Furthermore, the serum concentrations of phenols were closely correlated with cecal concentrations. This finding suggested that concentrations of phenols in the serum reflected phenol production in the cecum contents. These results showed that dietary intake of GOS could modify the intestinal environment, and suppress the production of phenols in the intestinal tract and the accumulation of phenols in the serum. Thus, GOS may help improve the quality of life (QOL) of patients with renal failure.