Abstract:
A nutritional composition is disclosed which comprises synergistic functional carbohydrates for preventing or treating infection by pathogenic bacteria and/or promoting gut flora balance and health. The carbohydrates have a synergistic activity on promoting bifidobacteria in the intestine. Also disclosed are a method of production of the composition; and a method of treatment of infection by pathogenic bacteria and/or promoting gut flora balance and health which comprises administering an effective amount of the composition.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     This application is a divisional of the U.S. patent application Ser. No. 10,350,092, filed Jan. 24, 2003, which is a continuation of the U.S. national phase designation of International application PCT/EP01/08283, filed Jul. 17, 2001, the entire contents of both of which are expressly incorporated herein by reference thereto. 
    
    
     BACKGROUND ART  
     The present invention relates to a nutritional composition which comprises synergistic functional carbohydrates for prevention or treatment of infection by pathogenic bacteria and/or promoting gut flora balance and health; a method of production of the composition; and a method of treatment of infection by pathogenic bacteria and/or promoting gut flora balance and health which comprises administering an effective amount of the composition. 
     It has been suggested that there are health benefits associated with growth of bifidobacteria populations in the gut. These benefits include increased defense against pathogenic bacteria, stimulation of the immune system, and health benefits relating to the production of short chain fatty acids (SCFAs), as well as less abdominal sensation. All of these influence gut flora balance and gut health. 
     It is well known that infection by pathogenic bacteria can be detrimental to health. Examples of these bacteria include  Clostridium perfringens, C. difficile, Salmonella  and other enteropathogens. 
     In the past, infection by these harmful bacteria has been allowed to proceed until it must be treated by antibiotics. The antibiotics have a good effect on harmful bacteria. However, they suffer from the problem that they also kill populations of intestinal bacteria that are not harmful and that aid digestion of food. These bacterial populations are often referred to as “friendly.” 
     Therefore, a need exists for a composition that is capable of preventing or combating infection by pathogenic bacteria, increasing defense against pathogenic bacteria, stimulating the immune system, and/or increasing short chain fatty acid production, all of which lead to promotion of gut flora balance and health. 
     The present invention addresses the problems set out above. 
     SUMMARY OF THE INVENTION  
     Remarkably, it has now been found that specific functional carbohydrates are capable of having a synergistic effect on the growth of bifidobacteria populations in vitro and in vivo in the gut. 
     Consequently, in one aspect, the present invention provides a method of treating Irritable Bowel Syndrome (IBS) in a patient in need of such treatment. The method comprises administering to the patient a nutritional composition comprising at least two synergistic functional carbohydrates, wherein a first carbohydrate is inulin or fructooligosaccharide (FOS) and a second carbohydrate is xylooligosaccharide (XOS), acacia gum or resistant starch. Advantageously, the carbohydrates are present in amounts effective to stimulate intestinal bifidobacteria, and the composition is administered in an amount effective to treat IBS by providing increased amounts of intestinal bifidobacteria. 
     The carbohydrates may be obtained commercially or more simply by the use of a natural source (e.g., chicory as source of inulin). The first and the second carbohydrates may be provided in a weight ratio of 1–20:0.1–20. 
     Further, the nutritional composition may be combined with a food, food-forming, beverage, or beverage-forming component to formulate an edible composition. The edible composition may be provided in the form of a powder or liquid concentrate, and may further comprise a fat source, such as a vegetable fat or animal fat, that provides about 5–55% of the energy of the edible composition. The edible composition may further comprise one or more of a protein source, a fat source, an additional carbohydrate source, an additional dietary fiber, a vitamin, a mineral or a food grade emulsifier. The first carbohydrate in the edible composition may be present in an amount of about 1 to 20 g, and the second carbohydrate may be present in an amount of about 0.1 to 20 g. 
     The present method can also be used to treat infection by pathogenic bacteria or to promote gut flora balance and health by administering an amount of the nutritional composition that is effective to stimulate intestinal bifidobacteria and thus to promote associated health benefits. The nutritional composition can also be administered in an amount effective to reduce side effects of consuming fiber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES  
         FIG. 1  shows the effect of various carbohydrates or blends thereof on fecal bifidobacteria in human. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Within the context of this specification the expression “side effects” is taken to mean undesirable effects often occurring after consumption of fiber. These side effects include, for example, flatulences, bloating and intestinal pain. 
     In humans and animals the bifidobacteria population is not the same from one individual to another and often comprises several different species of bifidobacteria. According to the present invention it is possible to stimulate specifically the growth of intestinal bifidobacteria or other lactic acid bacteria by the use of specific nondigestible carbohydrates (fiber or fiber-like substances), in vivo and in vitro. 
     The bifidobacteria enzymes implicated in the fermentation of embodiments of a composition according to the present invention are not identical depending on the physical and chemical structures of the carbohydrates. In addition, the bifidobacteria are not similar with regard to their enzymatic capacity, e.g., the ability to ferment one fiber or another. 
     Thus, a nutritional composition according to the invention which comprises a mixture of two carbohydrates or more promotes the growth of more bifidobacteria species than a single carbohydrate does. Surprisingly, a synergy exists between carbohydrates (examples of which include: fructooligosaccharides, galacto-oligosaccharide, soybean-gum, gum, starch) on the stimulation of bifidobacteria and their health benefits. 
     Preferably, one embodiment of the nutritional composition according to the present invention comprises fructooligosaccharide and a carbohydrate selected from the group which consists of xylooligosaccharide and acacia gum. More preferably, it comprises fructooligosaccharide and acacia gum. 
     Another embodiment of the nutritional composition according to the present invention comprises about 1 g to about 20 g of a first carbohydrate and about 0.1 to about 20 g of a second carbohydrate. More preferably, it comprises about 1 g to about 3 g of a first carbohydrate and about 0.2 g to about 3 g of a second carbohydrate for an infant, and about 2 g to about 5 g of a first carbohydrate and about 2 g to about 5 g of a second carbohydrate for an adult, although it will be apparent that there are no specific limitations except for what can reasonably be consumed and the price. The amounts given correspond to a daily dose, which may be divided into several servings in one day, if desired. 
     In yet another embodiment, a ratio by weight of the first and the second functional carbohydrate is 1–20:0.1–20. More preferably, it is between 0.05–10:1, even more preferably, between 0.1–10:1. 
     The invention also provides an edible composition formulated for human consumption and/or administration. This composition includes a food, food-forming, beverage, or beverage-forming component and one of the nutritional compositions of the invention. An alternative embodiment of this edible composition is formulated for consumption by a companion animal. 
     One advantage of the present invention is that it provides a composition that can be provided in a functional food product and which therefore does not require special administration. 
     Another advantage of the present invention is that it does not adversely kill or affect non-harmful intestinal bacteria. 
     Yet another advantage of the present invention is that it provides a decrease of the daily amount of carbohydrates required in the gut to obtain stimulation of intestinal bifidobacteria and for the promotion of the associated health benefits. The benefits that this decrease provides include reduction of the side effects (abdominal disturbance) induced by the intake of some fermentable carbohydrates, and in some cases a reduction in cost. 
     Yet another advantage of the present invention is that it provides a composition of carbohydrates having various lengths of carbohydrate chains. This enables modulating fermentation throughout the colon as the composition passes through it. 
     Additional features and advantages of the present invention are given below. Comparative data showing results in human studies of using fructooligosaccharides plus acacia gum or plus xylo-oligosaccharides are given in the Examples. The data demonstrate a greater increase of bifidobacteria with a synergistic mix of carbohydrates than with single carbohydrate. These examples are described below. 
     In an embodiment, the nutritional composition preferably comprises a source of protein. Dietary protein is preferred as a source of protein. The dietary protein may be any suitable dietary protein, for example an animal protein (such as milk protein, meat protein or egg protein); a vegetable protein (such as soy protein, wheat protein, rice protein, and pea protein); a mixture of free amino acids; or a combination thereof. Milk proteins such as casein, whey proteins and soy proteins are particularly preferred. 
     The composition may also comprise a source of fat. If the nutritional formula includes a fat source, the fat source preferably provides about 5% to about 55% of the energy of the nutritional formula; more preferably about 20% to about 50% of the energy. Lipids making up the fat source may be any suitable fat or fat mixture. Vegetable fat is particularly suitable, for example, soy oil, palm oil, coconut oil, safflower oil, sunflower oil, corn oil, canola oil, lecithins, and the like. Animal fat such as milk fat may also be added if desired. 
     An additional source of carbohydrate may be added to the nutritional composition. It preferably provides about 40% to about 80% of the energy of the nutritional composition. Any suitable carbohydrate may be used, for example, sucrose, lactose, glucose, fructose, corn syrup solids, maltodextrin, or a mixture thereof. 
     Additional dietary fiber may also be added if desired. If added, it preferably comprises up to about 5% of the energy of the nutritional composition. The dietary fiber may be from any suitable origin, including, for example, soy, pea, oat, pectin, guar gum, acacia gum, fructooligosaccharide or a mixture thereof. 
     Suitable vitamins and minerals may be included in the nutritional composition in an amount to meet the appropriate guidelines. 
     One or more food grade emulsifiers may be included in the nutritional composition if desired, for example, diacetyl tartaric acid esters of mono- and di-glycerides, lecithin and mono- or di-glycerides or a mixture thereof. Similarly, suitable salts and/or stabilizers may be included. 
     The nutritional composition is preferably enterally administrable, for example, in the form of a powder, a liquid concentrate, or a ready-to-drink beverage. If it is desired to produce a powdered nutritional formula, the homogenized mixture is transferred to a suitable drying apparatus such as a spray drier or freeze drier and converted to powder. 
     Alternatively, a common food product may be enriched with an embodiment of the composition. For example, a milk, such as a fermented milk, a yogurt, a fresh cheese, or a renneted milk, may be provided with the nutritional composition of the invention. The food product may also be a confectionery bar, breakfast cereal flakes or bars, a drink, milk powder, soy-based product, non-milk fermented product or a nutritional supplement for clinical nutrition, infant formulae or baby food. In these situations, the amount of the composition added is preferably at least about 0.01% by weight. 
     An embodiment of the composition may be included in an article of confectionery, for example a sweet or sweetened beverage. 
     EXAMPLES  
     The following examples are given by way of illustration only and in no way should be construed as limiting the subject matter of the present application. Percentages and parts are by weight unless otherwise indicated. 
     Example 1 
     A parallel design, consisting of 3 groups of 29 volunteers each, has been used:
     FOS: 6 g daily of (Raftilose P95N) during 6 weeks.   XOS: 0.4 g daily of Xylo-oligo P95 during 6 weeks   XOS FOS: 4 g daily of FOS and 0.2 g daily of XOS, during 6 weeks   

     Before the 6 weeks of treatment, a wash-out period of 3 weeks was observed. The participants were then followed-up during 5 additional weeks after the end of the treatment. During the wash-out and follow-up periods, the volunteers received a placebo. 
     During the complete test period, subjects refrained from eating fermented yogurts and products containing bifidus. 
     In general the test subjects showed an increase of bifidobacteria counts, particularly those who had a low initial value. The average and median increases were also calculated. A formal statistical analysis, shown below in Table I, gave the following results: 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Differences of bifidobacteria counts between 
               
               
                 start and first week of treatment 
               
             
          
           
               
                   
                   
                 start 
                 +1 week 
                 Difference 
                 p-value 
               
               
                   
                   
               
             
          
           
               
                   
                 FOS 
                   
                   
                   
                   
               
               
                   
                 [log 10  cfu/g] 
               
               
                   
                 Mean (t-test) 
                 8.41 
                 9.02 
                 +0.61 
                 0.019 
               
               
                   
                 XOS 
               
               
                   
                 [log 10  cfu/g] 
               
               
                   
                 Mean (t-test) 
                 7.43 
                 8.11 
                 +0.68 
                 0.042 
               
               
                   
                 XOS FOS 
               
               
                   
                 [log 10  cfu/g] 
               
               
                   
                 Mean (t-test) 
                 7.39 
                 8.85 
                 +1.45 
                 &lt;0.001 
               
               
                   
                   
               
             
          
         
       
     
     The results shown in the table provide clear indicate that FOS and XOS FOS significantly increase the average bifidobacteria counts. This is also the case for XOS, but to a lesser extent. The increase obtained with the mixed XOS FOS is synergistically higher. 
     Example 2 
     The trial was designed, according to the protocol, to compare three groups of 32 resp. 31 subjects in parallel: 
     FOS: 200 ml of skimmed milk with Raftilose P95®, 6 g per serving. 
     Fibergum: 200 ml of skimmed milk with Fibergum AS IRX®, 6 g per serving. 
     FOS+Fibergum: 200 ml of skimmed milk with Raftilose P95® (3 g per serving) and Fibergum TX® (3 g per serving). 
     Feces samples were tested 7, 21, 28, 49 and 71 days after the start of the study. The intervention period is between day 21 and 49. The change from day 21 to day 28 is of particular interest. 
     According to the protocol, a +1.35 log 10  cfu/g of feces increase of Bifidobacteria after one week of treatment is expected for the FOS+Fibergum group. 
     The individual changes in the FOS+Fibergum group from day 21 to day 28 are summarized below: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Min. 
                 1st Qu. 
                 Mean 
                 3rd Qu. 
                 Max. 
               
               
                   
               
             
             
               
                 −0.33 
                 0.07 
                 1.384 
                 1.42 
                 6.73 
               
               
                   
               
             
          
         
       
     
     The differences were analyzed in two ways, first from a quantitative point of view, then more from a qualitative point of view. 
     Use of a robust location estimator, for example the M-estimator using Turkey&#39;s bisquare function gave an “average” of 0.307 log 10  cfu/g of feces, close to the median value. A 95% confidence interval was calculated by bootstrapping 1000 times (this is why the M-estimator was preferred compared to the median in this case). This gave as limits 0.14 and 1.00, that is an interval which does not include the value 0, indicating that the increase was statistically significant. 
     The “responders” were determined with the criteria of an increase of at least +0.5 log 10  cfu/g of feces. This was observed for 13 out of 29 subjects, which represented 44.8% of the volunteers. A 95%-confidence interval for this proportion was from 27 to 64%. We could say that at least 27% of the subjects responded to the diet provided, and it could be as high as 64%. 
     Using both approaches, significant results were obtained. 
     For the Fibergum group, we obtained the following differences: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Min. 
                 1st Qu. 
                 Mean 
                 3rd Qu. 
                 Max. 
               
               
                   
               
             
             
               
                 −6.26 
                 0 
                 0.6678 
                 0.875 
                 6.6 
               
               
                   
               
             
          
         
       
     
     Here, median and mean differences were closer, and a t-test was appropriate. The average increase was at the limit of statistical significance (p-value=0.09, 95%-C1: [−0.11, 1.45]). 
     Finally, for the FOS group, the differences were distributed as follows: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Min. 
                 1st Qu. 
                 Mean 
                 3rd Qu. 
                 Max. 
               
               
                   
               
             
             
               
                 −4.04 
                 0.0625 
                 0.2853 
                 0.655 
                 4.31 
               
               
                   
               
             
          
         
       
     
     Example 3 
     100 volunteers were assigned randomly to 4 diet groups, but stratified for their amount of native intestinal Bifidobacteria before the trial based on gender, age and average portions of fiber in the daily diet. The 4 diet groups are described below: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Control 
                 Reference Product 
               
               
                 FOS + GUM 
                 Raftilose ® 3 g and Fibergum 3.56 g per serving 
               
               
                 Starch 
                 Resistant Starch 10 g per serving 
               
               
                 Blend 
                 Raftilose ® 3 g + Fibergum 3.56 g + Resistant Starch 10 g 
               
               
                   
                 per serving 
               
               
                   
               
             
          
         
       
     
     The primary analysis as to the outcome is the effect on the amount of Bifidobacteria in the feces. Counts of other micro-organisms were also analyzed. A further analysis was carried out to determine changes of abdominal sensation (flatulencies, quality and number of stools) as assessed by the volunteers, followed by an analysis of several short chain fatty acids measured in the feces. 
     The 100 volunteers were allocated to 4 groups as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Control: 
                 13 subjects (8 females, 5 males) 
               
               
                   
                 FOS + GUM: 
                 29 subjects (19 females, 10 males) 
               
               
                   
                 Starch: 
                 29 subjects (19 females, 10 males) 
               
               
                   
                 Blend: 
                 29 subjects (19 females, 10 males) 
               
               
                   
                   
               
             
          
         
       
     
     Their average amounts of bifidobacteria, ages and portions of fiber were similar. There was one subject who clearly was not in compliance (Group “FOS+GUM”), and its data were omitted. 
     It was set out to demonstrate that after 4 weeks of treatment, 50% of the subjects showed an increase of at least +0.5 log 10  cfu/g of bifidobacteria in feces. The lower boundaries of a 95%-Confidence Interval (CI) for the estimated proportion should be above 25%. 
     For the duration “Day 20 to Day 48”, the following results were obtained of log 10  cfu bifidobacteria/g feces (p) in (n) number of people. The number of people having at least 0.5 log 10  cfu/g is shown in the first column (+0.5). 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Bifidobacteria: 
               
             
          
           
               
                   
                 Day 48 minus day 20 
               
             
          
           
               
                   
                 +0.5 
                 n 
                 p 
                 Lower 
                 Upper 
               
               
                   
               
             
          
           
               
                 Control 
                 3 
                 13 
                 23.1 
                 6.2 
                 54.0 
               
               
                 FOS + GUM 
                 9 
                 27 
                 33.3 
                 17.2 
                 54.0 
               
               
                 Starch 
                 7 
                 27 
                 25.9 
                 11.9 
                 46.6 
               
               
                 Blend 
                 13 
                 27 
                 48.1 
                 29.2 
                 67.6 
               
               
                   
               
             
          
         
       
     
     In the above table, we see that, in the Control group, there were 3 out of 13 subjects that have an increase of at least 0.5 log 10  cft/g of feces. This represents 23.1%, with a 95%-confidence interval (CI) ranging from 6.2% up to 54.0%. For the Blend, the proportion was close to 50%, and the lower boundary of the 95%-Cl is above 25%. Clearly there was a significant effect after 4 weeks of consuming the blend. 
     After 1 week, the following results were obtained: 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Bifidobacteria: 
               
             
          
           
               
                   
                 Day 27 minus day 20 
               
             
          
           
               
                   
                 +0.5 
                 n 
                 p 
                 Lower 
                 Upper 
               
               
                   
               
             
          
           
               
                 Control 
                 5 
                 13 
                 38.5 
                 15.1 
                 67.7 
               
               
                 FOS + GUM 
                 12 
                 28 
                 42.9 
                 25.0 
                 62.6 
               
               
                 Starch 
                 9 
                 28 
                 32.1 
                 16.6 
                 52.4 
               
               
                 Blend 
                 11 
                 29 
                 37.9 
                 21.3 
                 57.6 
               
               
                   
               
             
          
         
       
     
     Here, the effect of FOS+GUM was significant, and the blend was at the limit of statistical significance. 
     Changes in the amount of bifidobacteria were checked after 1 and 4 weeks of treatment to assess whether they related to the average portions of fiber eaten per subject. No striking association was found. 
     Similar experiments were carried out to determine the amounts of lactobacilli, bacteroides, enterobacteria and clostridium per fingens. It was surprisingly found that the number of these bacteria did not change significantly with respect to the different diets. This demonstrated the surprising result that an embodiment of the invention has the effect of specifically enhancing bifidobacteria. This result positively affects digestion, combats infection by pathogenic bacteria, stimulates the immune system, increases short chain fatty acid production and leads to promotion of gut flora balance and health. 
     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be encompassed by the appended claims.