Patent Publication Number: US-11045509-B2

Title: Tributyrin compositions and methods therefor

Description:
This application is a divisional application of co-pending US application having Ser. No. 16/434,051, which was filed Jun. 6, 2019. 
    
    
     FIELD OF THE INVENTION 
     The field of the invention is tributyrin compositions and methods thereof for improving gut health, particularly as it relates to enhancement of  Bifidobacteria  in the gut microbiome. 
     BACKGROUND 
     The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. 
     The human gastrointestinal tract harbors an estimated 39 trillion bacterial residents which are commonly referred to as the “gut microbiota” or the “gut microbiome.” The specific make-up of these bacterial residents is reported to be intricately related to health and wellness. Specific changes in the composition of the gut microbiota have been implicated in the development of metabolic syndrome (Ridaura et al., 2013,  Science,  341, (6150)), cardiovascular disease (Tang and Hazen, 2014,  J. Clin. Invest,  124, 4204-4211), and cancer (Zitvogel et al., 2015,  Sci Transl Med,  7, (271)). Accordingly, there is growing appeal for evidence-based nutraceutical strategies targeting the proliferation of healthy “good” microbial species using prebiotics, while simultaneously suppressing the deleterious influence of harmful pathogens. 
     Most typically, prebiotics comprise soluble and insoluble dietary fiber often found in edible plants, and isolated complex compounds such as galacto-oligosaccharides or fructo-oligosaccharides. Prebiotics are often effective to increase proliferation of the gut microflora. However, many prebiotics will indiscriminately stimulate growth of a variety of bacterial species and so may actually contribute to a less than desirable overall microbiome. Moreover, depending on the type of prebiotic and gut microflora, fermentative degradation of the prebiotic may lead to significant gastrointestinal upset and flatulence. 
     While a large number of prebiotics have been widely discussed in gut health, postbiotics (i.e., the metabolic byproducts that are responsible for many of the beneficial effects of probiotic microorganisms) may provide more direct and possibly even greater health benefits. For example, the postbiotic butyric acid is a short chain fatty acid (SCFA) typically produced by microorganisms in the colon from undigested portions of fiber (e.g., as found in vegetables). Notably, butyric acid is also a major energy source for the cells lining the colon. However, a concentrated and effective form of dietary butyric acid is not readily straightforward because butyric acid is rapidly absorbed in the upper gastrointestinal tract prior to reaching the colon. 
     To circumvent absorption issues to at least some degree, the sodium salt of butyric acid (sodium butyrate) can be administered as sodium butyrate is a solid and more stable than the free acid. Orally administered sodium butyrate is able to reach both the small and large intestines where it dissociates to butyrate. However, while at least some of the butyrate will reach the colon, a significant portion of the sodium butyrate is metabolized in the small intestine, thereby decreasing the overall yield of ingested butyric acid. Additionally, the odor of sodium butyrate and butyric acid is often considered foul, making voluntary consumption and marketing difficult. 
     In other known nutraceutical strategies to help desirable microbial species colonize the intestinal tract, one or more probiotic strains may be ingested, typically in freeze-dried form. Among other suitable probiotic strains, various  Lactobacillus  and  Bifidobacterium  species and their varieties have been reported beneficial in various aspects. However, most of the probiotic strains that are ingested as a dietary supplement (e.g., as a capsule with freeze dried bacteria) will only poorly colonize the colon. Moreover, even if delivered to the colon, probiotic strains may be outcompeted in the colon by other commensal species. 
     Therefore, even though various pre- and probiotic supplements are known in the art, various disadvantages nevertheless remain. Therefore, there is still a need to provide improved compositions and methods to enhance gut health, especially as it relates to enhancement of desirable  Bifidobacteria  in the gut microbiome. 
     SUMMARY OF THE INVENTION 
     The inventive subject matter is drawn to various methods and compositions for increasing the levels of the probiotic  Bifidobacteria  in the gut of a mammal, and preferably a human. The various methods and compositions of the present disclosure include tributyrin-containing as well as tributyrin-enhanced compositions for selectively increasing the levels of  Bifidobacteria  in the gut microbiome of a mammal. Tributyrin-containing compositions include compositions that comprise tributyrin and/or a tributyrin derivative. 
     In one aspect of the inventive subject matter, the inventors contemplate a method for selectively increasing levels of  Bifidobacteria  in the gut of a mammal that includes providing a tributyrin-containing composition at an effective dosage. An effective dosage may include an amount of tributyrin or a tributyrin derivative of or between 50 mg up to 1,000 mg. Typically, the amount of tributyrin or a tributyrin derivative is between 100 mg up to 500 mg (e.g., 300 mg). Additionally, the tributyrin-containing composition may be processed to mask odor and/or may include at least one odor-masking component. Example processes and components of odor-masking include dextrin complexation and/or lipid complexation. The tributyrin-containing composition may be or may include a tributyrin derivative selected from butyrate mono-ester, butyrate di-ester, beta hydroxybutyrate, monobutyrin, dibutyrin, triacetin, tripropionate, glyceryl monoacetate, glyceryl diacetate, or acetoacetate. In addition to providing a tributyrin-containing composition, the method may also include providing at least one probiotic microorganism selected from  Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus gasseri, Lactobacillus rhamnosus, Bifidobacterium lactis, Bifidobacterium breve , and  Bifidobacterium longum . Alternatively or in addition to the probiotic microorganism, the tributyrin-containing composition may also include at least one additive selected from superoxide dismutase (SOD), compositions comprising activators of SOD, foods or extracts thereof comprising bioavailable SOD, copper I (Cu I), selenium (Se), fulvic acid, compositions comprising fulvic acid, Co-enzyme Q 10  (ubiquinone), pyrroloquinoline quinone (PQQ), an arabinoxylan (AX), an arabinoxylan oligosaccharide (AXOS), xylooligosaccharide (XOS), fructooligosaccharide (FOS), galactooligosaccharide (CROS), inulin, pectin, or combinations thereof. 
     In another perspective, the inventors also contemplate a method of increasing a probiotic benefit of a food item comprising a  Bifidobacterium  strain in which the method includes combining the food item with a tributyrin-containing composition (tributyrin or a tributyrin derivative as disclosed herein) which is present in the food item in an amount that selectively increase the levels of  Bifidobacteria  in the gut upon ingestion of the food item. Additionally, the tributyrin-containing composition in the food item may be processed to mask odor and/or may include at least one odor-masking component as disclosed herein. Also, the tributyrin-containing composition may include an amount of tributyrin or a tributyrin derivative of or between 50 mg up to 1,000 mg or 100 mg up to 500 mg. 
     In other aspect of the inventive subject matter, the inventors contemplate a dietary supplement including a nutritionally acceptable carrier in combination with a  Bifidobacterium  strain and further comprising tributyrin or a tributyrin derivative as disclosed herein, in which the carrier, the  Bifidobacterium  strain, and the tributyrin or a tributyrin derivative are formulated in a single oral dosage form. Any  Bifidobacterium  strain may be beneficial, and exemplary species include  Bifidobacterium lactis, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium breve , and  Bifidobacterium longum . The single oral dosage form may be a capsule or liquid (e.g., a drink). Additionally, the single oral dosage form may be processed to mask odor and/or may include at least one odor-masking component as disclosed herein. It is also contemplated that the  Bifidobacterium  strain is freeze dried. The single oral dosage form may include  Bifidobacteria  in an amount between 10 6  and 10 12  CFU/g. As disclosed herein, the tributyrin-containing composition of the single oral dosage may include an amount of tributyrin or a tributyrin derivative of or between 50 mg up to 1,000 mg or 100 mg up to 500 mg. 
     The inventors further contemplate a composition for increasing levels of  Bifidobacteria  in the gut of a mammal that includes a tributyrin-enhanced  Bifidobacterium  strain which has been grown in a culture medium comprising tributyrin or a tributyrin derivative as disclosed herein. Any  Bifidobacterium  strain may be grown in the presence of tributyrin or a tributyrin derivative, and exemplary species include  Bifidobacterium lactis, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium breve , and  Bifidobacterium longum . After culturing, the composition of the tributyrin-enhanced  Bifidobacterium  may optionally be combined with a tributyrin-containing composition (e.g., tributyrin or a tributyrin derivative). The tributyrin-containing containing composition may include tributyrin or a tributyrin derivative in an amount of or between 50 up to 1,000 mg. The tributyrin-enhanced  Bifidobacterium  strain, the tributyrin or the tributyrin derivative in the culture medium, and/or any tributyrin-containing composition added may each individually or collectively be processed to mask odor and/or may include at least one odor-masking component as disclosed herein. Additionally, the amount of the tributyrin-enhanced  Bifidobacterium  in the composition may be of or between 10 6  and 10 12  CFU/g. The composition may also include at least one additional probiotic microorganism selected from  Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus gasseri, Lactobacillus rhamnosus, Bifidobacterium lactis, Bifidobacterium breve , or  Bifidobacterium longum . The inventors have also contemplated the composition including at least one additive selected from superoxide dismutase (SOD), compositions comprising activators of SOD, foods or extracts thereof comprising bioavailable SOD, copper I (Cu I) selenium (Se), fulvic acid, compositions comprising fulvic acid, Co-enzyme Q 10  (ubiquinone), Pyrroloquinoline quinone (PQQ), an arabinoxylan (AX), an arabinoxylan oligosaccharide (AXOS), xylooligosaccharide (XOS), fructooligosaccharide (FOS), galactooligosaccharide (GOS), inulin, pectin, or combinations thereof. 
     The inventors also contemplate increasing levels of  Faecalibacterium prausnitzii  in the gut of a mammal by administering a tributyrin-containing composition to the mammal. The administration may be ingested in solid or liquid form and the tributyrin-containing composition includes tributyrin or a tributyrin derivative. Methods for increasing levels of  Faecalibacterium prausnitzii  in the gut of a mammal include administering the tributyrin-containing composition to mammals suffering from (e.g., diagnosed with) irritable bowel syndrome and/or Crohn&#39;s disease. 
     Various objects, features, aspects and advantages of the present invention will become more apparent from the detailed description of preferred embodiments of the invention, along with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a graph of the relative abundance of  Bifidobacterium  before (Pre) and after (Post) a 3-week protocol of 300 mg/daily of tributyrin in three subjects each indicated by a separate line connecting the Pre and Post data points. 
       FIG. 2  is a graph of the relative abundance of  Faecalibacterium  before (Pre) and after (Post) a 3-week protocol of 300 mg/daily of tributyrin in three subjects each indicated by a separate line connecting the Pre and Post data points. 
         FIG. 3  is a graph of the relative abundance of  Lachnospira  before (Pre) and after (Post) a 3-week protocol of 300 mg/daily of tributyrin in three subjects each indicated by a separate line connecting the Pre and Post data points. 
         FIG. 4  is a graph of the collective Firmicutes to Bacteroidetes (F/B) ratio in all three of the volunteer subjects before (PRE) and after (POST) a 3-week protocol of 300 mg/daily of tributyrin. 
     
    
    
     DETAILED DESCRIPTION 
     The inventors have now discovered that compositions including a tributyrin or a tributyrin derivative, as well as tributyrin-enhanced compositions confer an increase in the levels of the probiotic  Bifidobacterium  in the colon (large intestine). As used herein, an effect on the levels of  Bifidobacterium  may also be referred to as a “bifido effect.” 
     Tributyrin is a triglyceride and a butyrate ester that may be obtained by formal acylation of the three hydroxy groups of glycerol by butyric acid. As used herein, a derivative of tributyrin includes beta hydroxybutyrate, monobutyrin, dibutyrin, triacetin, tripropionate, glyceryl monoacetate, glyceryl diacetate, acetoacetate, a butyrate mono-ester, and a butyrate di-ester. 
     The inventors have found that administration of tributyrin confers a remarkable increase in the levels of  Bifidobacterium  found in the gut (e.g., colon) of a subject. To this end, aspects and embodiments of the present invention are directed to methods using and compositions of “tributyrin-containing” compositions and/or “tributyrin-enhanced” compositions, wherein tributyrin-containing compositions include any composition having tributyrin or a tributyrin derivative. 
     As used herein “subject,” “mammal,” or “mammal subject” may be used interchangeably to refer to any mammal to which the presently disclosed methods and compositions may be applied or administered. The mammal may have an illness or other disease, but the mammal does not need to be sick to benefit from the presently disclosed methods and compositions. The mammal may be in need of improving its gut and/or overall health, but the mammal may also have a generally healthy gut and desire to maintain or further improve their gut and/or overall health. As such any mammal may consume the disclosed compositions or be a recipient of the disclosed methods. More typically, a mammal as referred to herein includes a human or a domesticated animal. For example, domesticated animals include a dog, cat, or any farm animal including horses, cows, sheep, goats, pigs, or chickens. 
     As used herein, “administering” and like terms refer to the step of providing to and includes self-administering. Administering of any of the presently disclosed compositions include any mode by which the mammal can ingest the composition. Any suitable means of administration may be used so long as the composition reaches the colon. Accordingly, the form of the composition may be in any form suitable for ingestion to the colon. 
     Contemplated Methods and Compositions 
     In one exemplary aspect of the inventive subject matter, the inventors contemplate a method of selectively increasing levels of  Bifidobacteria  in the gut of a mammal with the administration of a tributyrin-containing composition to the mammal at a dosage that increases the relative abundance of  Bifidobacteria  in the gut of the mammal. 
     With reference to  FIG. 1 , tributyrin was taken by each of three volunteers for three weeks, after which time the relative abundance of  Bifidobacterium  was remarkably increased by 8,841%. With reference to  FIG. 2  and  FIG. 3 , the relative abundance (e.g., quantified amounts in a stool sample obtained before the three week study compared to quantified amounts in a stool sample after the three week study) was also increased for  Faecalibacterium  at 29% ( FIG. 2 ) and  Lachnospira  at 114% ( FIG. 3 ). However, the unexpected increase of  Bifidobacterium  indicates a tributyrin-containing composition confers a selective and remarkable increase in  Bifidobacteria.    
     Furthermore, the increase in  Faecalibacterium  observed in the colon includes  Faecalibacterium prausnitzii , the only known  Faecalibacteria  species. Accordingly, a method of increasing the relative abundance of  Faecalibacterium prausnitzii  in the gut of a mammal includes administering to the mammal tributyrin, tributryin-containing compositions, and/or tributryin derivatives in any formulation as disclosed herein for ingestion. The increase in  Faecalibacterium  is particularly advantageous as a low level of this species in the colon has been associated with irritable bowel disease and Crohns&#39; disease. Accordingly, it is contemplated that administration of tributyrin and/or derivatives thereof will increase  Faecalibacterium  in the colon and as such may at least provide symptomatic relief, and in some aspects reduce adverse signs and symptoms of irritable bowel disease and Crohns&#39; disease. 
     Similarly, a method of increasing the relative abundance of  Lachnospira  in the gut of a mammal includes administering to the mammal in need thereof tributyrin, tribuytrin-containing compositions, and/or tributyrin derivatives in any formulation as disclosed herein for ingestion. 
     Depending on the particular tributyrin-containing formulation and form, contemplated methods include an administration of at least 50 mg/day of tributyrin or a tributyrin alternative. This amount per day may be administered at once or in multiple doses. Typically, an effective amount of tributyrin or a tributyrin derivative in the tributyrin-containing composition to be administered at once or in multiple doses per day is of or between 50 milligrams (mg) to 1,000 mg. The dose or doses may be administered once a day for any period of time. For example, the effective dose may be administered each day for one day, a few days, multiple days, or on a daily basis indefinitely. More typically, the amount of tributyrin or a tributyrin derivative to be administered each day is of or between 100, 200, 300, 400, or 500 mg. Most typically, the amount of tributyrin or a tributyrin derivative to be administered each day is 300 mg. 
     To further enhance the gut health of the mammal, aspects of the contemplated methods of administering a tributyrin-containing composition include administering at least one probiotic microorganism concomitantly or subsequent to the administration of the tributyrin-containing composition. Any suitable probiotic or multiple probiotics may be combined with the tributyrin-containing composition. Exemplary probiotics include  Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus gasseri, Lactobacillus rhamnosus, Bifidobacterium lactis, Bifidobacterium breve , or  Bifidobacterium longum.    
     Multiple forms and formulations of the tributyrin-containing composition are contemplated for selectively increasing the  Bifidobacteria  in the gut. Particularly preferred compositions will be formulated as a nutritional or dietary supplement, in a (medical) food item, in animal feed, or as a pharmaceutical composition in liquid or solid form comprising the tributyrin-containing composition, and may optionally also include a nutritionally or pharmaceutically acceptable carrier. For example, where the composition is in solid form, the compositions may be formulated as a snack bar, yogurt, lozenge, tablet, or capsule, or may be coated onto cereal products, included in baked goods. On the other hand, where the supplement is in liquid form, the compositions may be formulated as a tincture, soft gel capsule, liquid capsule, syrup, carbonated drink, a brewed beverage (e.g., as coffee or tea), a juice, an energy drink, a sports drink, or flavored water. Tributyrin-containing compositions may also be formulated for used in pharmaceutical compositions, typically in combination with a pharmaceutically acceptable carrier where the tributyrin-containing composition is present in an amount to increase levels of  Bifidobacteria  in the gut. While nutritional and pharmaceutical compositions for human use are especially contemplated, it should be appreciated that the tributyrin-containing compositions and formulations may also be employed for veterinary use (e.g., use in animal feed for domestic companion animals (‘pets’) or in animal feed for farm animals. In further contemplated aspects, the tributyrin-containing composition may also be provided as a bulk product (e.g., in quantities of equal or greater than 100 g, equal or greater than 1,000 g, or equal or greater than 10 kg) for use in production of the nutritional supplement, a (medical) food item, animal feed, or pharmaceutical product. 
     Viewed from another perspective, tributyrin-containing compositions may also be added to a food item comprising a  Bifidobacterium  strain. The inventors contemplate a method of increasing the probiotic benefit of the food item comprising a  Bifidobacterium  strain by combining or adding a tributyrin-containing composition to the food item. In this way, the tributyrin or tributyrin derivative may be processed by the consumer concomitantly with the  Bifidobacterium  strain in the food item thereby enhancing the probiotic effects. As used herein, a food item includes any solid or liquid form of food or drink that may be consumed or ingested. As disclosed herein, the amount of the tributyrin-containing composition to be added to the food item comprising a  Bifidobacterium  strain may vary depending on the kind and form of the food item. Typically, the amount of the tributyrin-containing composition would be determined on an approximate per serving basis of the food item. More typically, the amount of the tributyrin-containing composition would be of or between 50 mg to 1,000 mg of tributyrin or a tributyrin derivative per serving of the food item. Most typically, the amount of the tributyrin-containing composition would be of or between 100, 200, 300, 400, or 500 mg of tributyrin or a tributyrin derivative per serving of the food item. 
     Contemplated methods and compositions also include a  Bifidobacterium  grown in the presence of tributyrin or a tributyrin derivative to produce a “tributyrin-enhanced”  Bifidobacterium . Aspects of this method include the addition of a tributyrin-containing composition to the culture medium of the  Bifidobacterium  strain during fermentation growth. Harvesting of the tributyrin-enhanced  Bifidobacterium  strain may occur at a cell concentration at or between 10 6  and 10 12  CFU/ml. After harvesting, the isolated tributyrin-enhanced  Bifidobacterium  strain cells may be suspended in a culture or the cells may be processed into an inactivated form (e.g., lyophilized/freeze dried) suitable for incorporation into a capsule or tablet, or as an additive in a food or drink. Additional aspects include combining the isolated tributyrin-enhanced  Bifidobacterium  strain in either the live active culture form or an inactivated form (lyophilized) may be combined with an additional amount of tributyrin or a tributyrin derivative. Typically, the amount of the additional tributyrin or tributyrin derivative is of or between 50 mg to 1,000 mg per 10 6  and 10 12  CFU/g of tributyrin-enhanced  Bifidobacterium  strain. More typically, the amount of the additional tributyrin or tributyrin derivative is 100, 200, 300, 400, or 500 mg per 10 6  and 10 12  CFU/g of tributyrin-enhanced  Bifidobacterium  strain. Any suitable probiotic  Bifidobacterium  strain may be grown in the presence of a tributyrin or a tributyrin derivative. Exemplary  Bifidobacterium  species  include Bifidobacterium lactis, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium breve , or  Bifidobacterium longum.    
     Additional aspects of the inventive subject matter may include adding the tributyrin-containing composition and/or a tributyrin-enhanced composition to a food item as disclosed herein. In a particular example, yogurt or a yogurt drink is a product which already contains bacteria species, such as  Lactobacillus bulgaricus  and  Streptococcus thermophilus , which are used for fermentation. Accordingly, it is contemplated that yogurt may be supplemented with a tributyrin-containing composition and/or a tributyrin-enhanced  Bifidobacterium  strain for a synbiotic product for gut health. 
     The inventors also contemplate that any of the presently disclosed tributyrin-containing compositions (e.g., in liquid or solid form or as a nutritional supplement) or tributyrin-enhanced compositions (e.g., a live active or inactive tributyrin-enhanced  Bifidobacterium  strain) may be processed to have a less unpleasant odor, minimal odor, no odor, or an odor that is not unpleasant. To this end, the inventors contemplate the tributyrin-containing and/or the tributyrin-enhanced compositions in a form that reduces or eliminates the native and unpleasant odor of tributyrin. Methods for eliminating, decreasing, and/or masking odors are established in the art. Typically, the tributyrin-containing or tributyrin-enhanced compositions as disclosed herein may be mechanically microencapsulation (e.g., lipid encapsulation) and/or complexed with cyclodextrin or maldextrin as described in U.S. Pat. No. 10,098,964. Further suitable protocols are described, for example, in Al-Kasmi et al., 2017,  J Control Release,  260, 134-141; Wyspianska et al., 2018,  Food Sci Nutr,  7, 805-816; and Zheng et al., 2018,  Pharmaceutics,  10 (157). 
     For additive bifido effects and in some cases synergistic bifido effects, the presently disclosed tributyrin-containing compositions (e.g., in liquid or solid form or as a nutritional supplement) or tributyrin-enhanced compositions (e.g., a live active or inactive tributyrin-enhanced  Bifidobacterium  strain) may be combined with one or both of the prebiotics of arabinoxylan (AX), an arabinoxylan oligosaccharide (AXOS), xylooligosaccharide (XOS), fructooligosaccharide (FOS), galactooligosaccharide (GOS), inulin, and/or pectin. Certain beneficial effects of these prebiotics have been previously described, e.g., Riviere et al., 2014,  App Env Microbio,  80, 204-217 and Pandey et al., 2015,  J Food Sci Technol,  52, 7577-7587. 
     In another aspect of the inventive subject matter, any of the presently disclosed tributyrin-containing compositions (e.g., in liquid or solid form or as a nutritional supplement) or tributyrin-enhanced compositions (e.g., a live active or inactive tributyrin-enhanced  Bifidobacterium  strain) may be combined with a health additive to increase the breadth of the health benefits. These health additives may be added in any combination with the tributyrin-containing compositions or tributyrin-enhanced compositions depending on the form of the composition as well as consideration for the desired health effect and product cost. Exemplary additives that may be combined with tributyrin-containing compositions or tributyrin-enhanced compositions include superoxide dismutase (SOD), compositions comprising activators of SOD, foods or extracts thereof comprising bioavailable SOD (e.g., sprouted wheat, wheatgrass, encapsulated (lipid and/or protein encapsulation) cantaloupe, rye, barley, barley grass, broccoli sprouts, kale, brussel sprouts, and curcumin (e.g., turmeric), copper I (Cu I), selenium (Se), fulvic acid, foods or extracts thereof comprising fulvic acid (e.g., potatoes, radishes, beets, carrots, root vegetables, blackstrap molasses, and shilajit), Co-enzyme Q 10  (ubiquinone) or pyrroloquinoline quinone (PQQ). 
     With reference to  FIG. 4 , the collective ratio of firmicutes to bacteroidetes (F/B ratio) was measured in the stool samples of the three volunteer subjects before and after taking tributyrin daily for three weeks as described in the Examples. The firmicutes and bacteroidetes are each a phylum of bacteria making up the largest portion of the human gut microbiome. In particular the F/B ratio has been reported to be associated with metabolic factors and cardiorespiratory fitness. Durk et al., 2018,  Int J Sport Nutr Exerc Metab,  29, 249-253. Accordingly, the inventors contemplate a method of increasing the F/B ratio in the gut of a mammal with the administration of a tributyrin-containing composition to the mammal at a dosage that effectively increases the F/B ratio in the gut of the mammal. As shown in  FIG. 4 , the collective F/B ratios from the three volunteers as measured before and after the study, indicated an increase of approximately 50%. Notably, while previous studies had associated an increased F/B ratio with an increased body mass index ( BMC Microbiol.  2017; 17:120), such increase was deemed at least in part due to an improved nutrient absorption. As such, contemplated compositions are thought to not only selectively improve gut microflora, but also to enhance nutrient uptake. 
     EXAMPLES 
     The inventors recruited three volunteers who were asked to provide some basic anthropometric characteristics and lifestyle habits. All volunteer subjects (2 female and 1 male) were free of chronic disease and reported not having taken an antibiotic within the past six months. Body mass index (kg/m 2 ) analysis classified two of the subjects as “overweight” (BMI&gt;25&lt;30), and one as obese (BMI&gt;30). Although activity habits varied, all of the subjects reported weekly participation in light-to-moderate physical activity, and relatively low caffeine intake (&lt;200 mg/day) and alcohol intake (&lt;3 drinks a week). 
     Before the start of the 3-week study, stool samples were collected from each of the 3 volunteers using the commercially available UBiome Explorer kit. The collected stool samples were sent to Ubiome labs (San Francisco, Calif.) where DNA was extracted followed by 16S rRNA gene amplification for bacterial classification. 
     The 3-week study involved each of the volunteers taking 300 milligrams (mg) of tributyrin per day for 3 weeks. Subjects were verbally instructed to maintain usual dietary and physical activity habits throughout the course of the study. 
     At the end of the 3-week period, stool samples were collected following the same protocol, and sent for analysis. 
     The bacterial classification analysis was carried out on the stool sample collected before study (PRE) and the stool sample collected after the study (POST) for each of the 3 volunteers. 
       FIGS. 1, 2, and 3  are each a graph of the change in relative abundance of  Bifidobacteria, Faecalibacterium , and  Lachnospira , respectively, found in the PRE stool sample and the POST stool sample where each line represents the change in amount for each volunteer. 
       FIG. 4  is a graph of the ratio of Firmicutes to Bacteroidetes (F/B ratio) in all three of the PRE study stool samples (left white bar) and all three of the POST study stool samples (right black bar). 
     The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the full scope of the present disclosure, and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the claimed invention. 
     It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C . . . and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.