Background: Health-related quality of life (HRQoL) has been rarely evaluated as a primary endpoint in the assessment of the effect of probiotics on the irritable bowel syndrome (IBS).

Aim: To study the effects of fermented milk containing Bifidobacterium animalis DN-173 010 and yoghurt strains on the IBS in a multicentre, double-blind, controlled trial.

Methods: A total of 274 primary care adults with constipation-predominant IBS (Rome II) were randomized to consume for 6 weeks either the test fermented milk or a heat-treated yoghurt (control). HRQoL and digestive symptoms were assessed after 3 and 6 weeks on an intention-to-treat population of 267 subjects.

Results: The HRQoL discomfort score, the primary endpoint, improved (P < 0.001) in both groups at weeks 3 and 6. The responder rate for the HRQoL discomfort score was higher (65.2 vs. 47.7%, P < 0.005), as was the decrease in bloating score [0.56 ± (s.d.)1.01 vs. 0.31 ± 0.87, P = 0.03], at week 3 in the test vs. the control group. In those subjects with <3 stools/week, stool frequency increased (P < 0.001) over 6 weeks in the test vs. control group.

Conclusions: This study suggests a beneficial effect of a probiotic food on discomfort HRQoL score and bloating in constipation-predominant IBS, and on stool frequency in subjects with <3 stools/week.

A colony immunoblotting method bas been developed to allow detection of the probiotic Bifidobacterium animalis strain DN-173 010 in human faecal samples. Rabbits were immunized with heat-killed DN-173 010 bacteria resulting in the production of an antiserum highly specific for bacteria belonging to Bif. animalis species. Of the 89 strains representative of 29 different bifidobacterial species tested, only the 15 strains of the Bif. animalis species could be detected with the antiserum. ln Western immunoblotting the serum reacts with a protein of 45-kDa apparent molecular weight. None of the bacteria classically encountered in human faecal samples and able to grow on non-selective Columbia blood agar (enterobacteria, Bacteroides or Lactobacillus for instance) reacted with the antiserum. Taking advantage of the high specificity of the antiserum and of the absence of Bif. animalis bacteria in faeces samples of five human volunteers, we demonstrated that strain DN-173 010 survives the intestinal transit. Being based on a combination of semiselective cultivation and colony immunoblotting techniques, the method allowed detection of the Bif. animalis strain even when it represented only one thousandth of the total bifidobacterial population.

The ability of a strain of Bifidobacterium sp to survive passage through the upper gastrointestinal tract when ingested in fermented milk was investigated in six fasting healthy adults by using in vivo ileal perfusion. After ingestion of 10.0 ± 0.5 log₁₀ bifidobacteria in 400 g fermented milk, ileal flow of bifidobacteria increased significantly and reached a maximum of 8.8 ± 0.2 log₁₀ bifidobacteria/h 1.7 ± 0.4 h after ingestion of fermented milk. The average number of bifidobacteria recovered from the terminal ileum during the 8 h after fermented-milk ingestion was 9.0 ± 0.1 log₁₀ and constituted 23.5 ±10.4% of the number ingested. These results indicate that in healthy adults Bifidobacterium sp survive transit through the gastrointestinal tract when ingested in fermented milk. Further studies are needed to investigate the behavior of these exogenous bacteria in the colonic lumen and to explore their effects on the physiology of the human gastrointestinal tract.

Two Bifidobacterium strains contained in two different fermented rnilks behave very differently when exposed to an in vitro simulated gastric environment. One strain survives very weIl during at least 90 min (> 10⁷/g ), but the second strain studied is much less resistant. These in vitro results, with slight differences, were confirmed by an in vivo study in humans. The assessmen of the gastric emptying rate of these products allows an estimation of the amount of Bifidobacterium that may pass into the small intestine. (Key words: Bifidobacterium, fermented milks, gastric transit)

Since many authors considered that Bifidobacteria (Bif) play an important role in the resistance of the colonic microflora to pathogen colonization, there has been renewed interest in the consumption of milk fermented with these bacteria (BM). However data on the survival of ingested Bif in the GIT are not yet available. Therefore, we investigated the recovery of Bif ingested in BM in the feces of 12 adults (6 men and 6 women, 17-50 yr). The experiments comprised 3 consecutives 10-day periods: baseline, the test period, the washout period. During the test period subjects ingested 3 times per day 125 g BM (10⁸ Bif/g) or yogurt (Y). Spores of Bacillus (SBS) were added to both fermented products (10⁵ SBS/g) as a transit marqueur. AlI the subjects were tested for BM and Y in a random order: Fecal samples were obtained every 5th day and Bif were enumerated on selective medium incubated anaerobically for 5 days at 37ºC and SBS on PCA agar incubated aerobically for 24 h at 65ºC. Key-words : Bifidobacterium -Bifidus milk -Intestinal flora.

From the ¹Danone Vitapole, 92350 Le Plessis-Robinson, France and ²ISERNT -ALPE ADRIA, Trieste, Italy.

Fermented milks have been proposed to modulate gut transit time. Reduction of long transit times may be of importance in decreasing susceptibility to some large bowel diseases. Objective: to assess the effect on gut transit time in free-living elderly of a regular consumption of the milk fermented by the probiotic strain Bifidobacterium animalis DN-173 010 (10⁸ CFU/g) and lactic acid cultures (10⁸ CFU/g) (BM). Design: a randomized study was performed with 4 groups: 50 subjects with a stable transit time under 40 h (UTT: 24.6 h, SD = 1.7) and 50 subjects with a stable transit time over or equal to 40 h (OTT: 64.1 h, SD = 13.3) were included. Subjects from each transit group were randomly assigned to eat during 2 weeks, either 2 or 3 servings per clay of BM. The oro-fecal transit time was measured before and after BM consumption using a colored marker technique. Results: in the 4 groups, comparing values before and after BM consumption, the transit time reductions were statistically significant, being around 10% in UTT and around 40% in OTT (p < 0.001). ln UTT as well as in OTT, 3BM were more active than 2BM (p < 0.05). Conclusions: in elderly, the long gut transit times have been shortened by a 2-week regular consumption of the milk fermented with the strain Bifidobacterium animalis DN-173 010 and lactic cultures. This specific fermented milk can be considered as a functional food.

Objectives: The aim of our study was to ascertain whether the specific Bifidobacterium animalis DN-173 010 fermented milk could modulate colonic transit time in humans. Bifidobacteria are a major component of the gut microflora and may interact with gut transit. Methods: The trial compared in a parallel double blind study in seventy two healthy volunteers the effect of a Bifidobacterium animalis fermented milk containing 2.6×10⁸ CFU/g living bifidobacteria versus heat-treated Bifidobacterium fermented milk on colonic transit times. The main marker was the total colonic transit time (CTT) measured with radio-opaque pellets. Segmental colonic transit times were also calculated. Results: A 11-day-consumption of this Bifidobacterium animalis DN-173 010 fermented milk significantly reduced the total CTT (-20.6% ) comparatively to the initial CTT and to the control group where no significant change were recorded. The effect was more pronounced in women than in men. Conclusion: Our study demonstrated that the consumption of the fermented milk containing living Bifidobacterium animalis DN-173 010 was able to improve CTT in humans.

Background: A previous study bas suggested that Bifdobacterium animalis DN-173 010 shortens the colonic transit time in women. Aim: To confirm this effect and to determine whether modifications of the faecal bacterial mass and/or faecal secondary bile salts may be the explanation. Methods: A double-blind, cross-over study was performed. Thirty-six healthy women were studied in four consecutive10-day periods. During periods 2 and 4, they ingested three 125 g cups per day of a fermented milk which was either a product containing DN-173 010 or a control without bifidobacteria. Periods 1 and 3 were run-in and washout periods, respectively. The total and segmentaI colonic transit times were assessed using a pellet method. In 12 subjects, aIl stools were collected and analysed for pH, faecal weight, bacterial mass and bile acids. Results: The total and sigmoid transit times were significantly shorter during dosing with B. animalis compared to the control period. The other transit times, faecal weight, pH, bacterial mass and bile acids were not significantly affected. Conclusions: B. animalis DN-173 010 shortens the colonic transit time in healthy women. This effect is not explained by modifications of the faecal bacterial mass or secondary bile acids.

Fermented milk products containing the probiotic strain Bifidobacterium animalis DN-173 010 (BM) have a beneficial effect in reducing gut transit times in a range of populations including adults and the elderly, especially female. The aims of this study were to investigate the efficacy of one and two servings per day of BM in elderly subjects and to determine the duration of the reduction in transit times after stopping consumption of the product. This was a randomized controlled and open study with four groups; 200 elderly subjects (aged 50-75 years) were à enrolled in the trial. In all, 100 subjects with medium transit times (MTT, 40-50 h) and 100 with slow transit times (STT, >50 h) were randomized to receive either 125 g or 250 g BM daily for 2 weeks. Oro-faecal gut transit was determined by the use of coloured markers. Both dosages significantly reduced oro-faecal transit time with reductions of 20.5% and 42.2% observed in MTT subjects receiving BM 125 g/day and 250 g/day, respectively (p<0.0001). Corresponding reductions in STT subjects were 27.7% and 38.1%, respectively. The beneficial effects of BM lasted long after consumption of the product was stopped, with values returning to baseline in subjects with MTT at 6 weeks follow-up and in STT subjects consuming 125 g/day BM at 4 weeks follow-up. Significant differences in transit times were still observed at week 6 of follow-up in STT subjects receiving 250 g/day BM. This study completes and confirms the dose-dependent effects of BM from 0 to 250 g per day and can be compared with similar results obtained with 250 to 375g per day in a previous study on transit times in elderly subjects. It also demonstrates that there are significant beneficial effects long after consumption of the product has stopped. The results suggest an important role for this probiotic dairy product in fundamentally modulating gastrointestinal function that could beneficially affect the host, and hence reduce the susceptibility to conditions associated with delayed gut transit.