What they are and what their importance in feeding dogs and cats is
Within the intestines of these pets usually inhabits a large microbiota that performs important beneficial functions on their health. The incorporation of certain nutrients in balanced food favors the growth and metabolic activity of this population of microorganisms, which contributes to reinforcing the positive effects on the health of the intestine and the organism.
Prebiotics are indigestible components of balanced food that produce beneficial effects on the health of animals that ingest it through the selective stimulation of the growth of one or more species of bacteria, which normally inhabit the colon, and which help to protect the health of the organism of both dogs and cats.
In 1995, Professor Glenn Gibson from the University of Reading, England, first coined and defined the term “prebiotic” in a paper that at the time became one of the most quoted by his peers in the world scientific community.
Based on this advance in biomedical knowledge, the incorporation of prebiotics in the formulation of Premium and super Premium balanced food for pets was added to the development of other nutritional concepts, such as probiotics, which together aim to define the conceptual framework of the so-called functional or nutraceutical food, that is, those that combine nutritional properties with attributes that help to cure, or prevent, certain health disorders in living beings.
Polysaccharides constitute a group of nutrients that mostly, fulfill prebiotic functions since they positively affect pets’ health. Under the generic name of “dietary fiber” are included all the polysaccharides incorporated with the diet that cannot be digested by the enzymes present in the small intestine of animals. But from a biochemical point of view, this term is ambiguous and artificial since it groups together a heterogeneous set of very different molecules, some of which, like lignin, are not actually polysaccharides. In this sense, some authors prefer to use the term “soluble or fermentable fiber”, excluding lignin and cellulose from this group.
For a polysaccharide to be considered a prebiotic nutrient, it must meet three basic requirements: first, it must resist enzymatic digestion by the organism that consumes it; in other words, it must reach the large intestine of the animals intact. Second, it must be fermentable by the action of bacteria in the gastrointestinal tract. Finally, it must act as a food substrate that selectively favors population growth and the metabolic activity of certain beneficial intestinal bacteria, particularly Lactobacillus and bifidobacteria. On the contrary, these polysaccharides should not be available for the use of other microorganisms that are potentially pathogenic for animals such as Clostridium, Salmonella o Escherichia coli, among others.
The main polysaccharides that have prebiotic properties are those derived from fructans, such as inulin, and fructooligosaccharides (FOS). These nutraceutical ingredients are commonly found in the formula of good quality feed.
Fructans are natural reserve carbohydrates in vegetables, as is starch. But, unlike this one, which is made up of glucose chains, fructans are polymers made up of several units of another monosaccharide: fructose, commonly called fruit and honey sugar. Depending on the length of this chain, fructan is called FOS, when it does not exceed 20 fructose units, or Inulin when the amount of monomers is greater. In nature, fructans are found in the roots of chicory and beets, among other vegetables. Within cereals, wheat is the richest source of FOS and Inulin.
Inulin and other natural fructans make up most of the soluble fiber that is indigestible by enzymes present in the small intestine. This is because the monosaccharide units that make up these fibers are linked together by ß- (2-1) bonds that are resistant to enzymatic action. For this reason, they can reach the final tract of the large intestine without being metabolized.
It is known that the contribution of natural fructans in the balanced food consumed by dogs and cats modulates the composition of their intestinal flora, fundamentally acting as a substrate that favors the growth and metabolic activation of certain types of bacteria. Several experimental in vitro studies demonstrated that both Inulin and FOS present in pet food are selectively metabolized by bifidobacteria and that this fermentation produces a higher acidity in the medium that inhibits the growth of pathogenic bacteria. Bifidobacteria in the intestine are known to be the main components of the microbiological barrier against infection.
The intestinal microbiota of pets is made up of an estimated population of about 1010 microorganisms per gram of dry fecal matter. This numerous microbiota fulfills various functions related to the normal digestion and assimilation of food, the prevention or development of intestinal diseases, depending on the predominant bacterial genus, etc.
For this matter, the presence of soluble or fermentable fibers, such as FOS, in the balanced pet food contributes to selectively increasing certain aerobic bacteria, fundamentally providing the necessary food and the most suitable environmental conditions for their development.
Once the soluble fibers reach the large intestine intact, the bacteria act on them, giving rise to a fermentation process, from which volatile fatty acids (VFA) are generated, also called short chain, such as butyrate, acetate and propionate, which are easily absorbable. The first one is the one that provides the greatest amount of energy to the colonocytes, despite representing only 15% of the total VFA that are formed in the intestine. It is known that the consumption of prebiotics can double the concentration of VFA in the intestine of dogs and cats.
The presence of FOS in the formula of balanced food for dogs and cats provides the following benefits for the normal functioning of the intestine and the health of these animals:
- Nourishes intestinal cells: VFA, particularly butyrate, which are produced in the intestine by the fermentation of soluble fibers, constitute the main energy source of the colonocytes of the lining epithelium of this organ. The contribution of prebiotics to the animals’ diet can double the amount of VFA in the gastrointestinal tract. This action is reflected in a better assimilation of nutrients with the consequent decrease in the volume of fecal matter eliminated.
- Increases calcium absorption: numerous studies in animals have shown that prebiotics increase the absorption of calcium in the colon, resulting in an increase in bone density and the trabecular structure of the bones. Prebiotics acidify the pH of the intestinal content, which favors the solubilization of minerals. At the same time, the presence of butyrate increases the absorption capacity of the cells of the intestinal mucosa. Prebiotics have also been shown to increase the efficiency of calcium transport systems across membranes. In addition, they contribute to increasing the intestinal absorption of magnesium and other cations.
- Helps prevent certain types of cancer: It is known that some genera of bacteria, in particular anaerobic ones, that inhabit the intestines of animals have the capacity to produce carcinogenic and tumor growth-promoting substances. It is proven that prebiotics in the diet have anticancer effects mainly from the production of metabolites that protect intestinal cells from these harmful substances. The most important of these metabolites is butyrate, which stimulates apoptosis, or programmed cell death, in colon cancer cell lines. At the same time, FOS reduce the amount of genotoxic enzymes and increase the intestinal population of healthy bifidobacteria. Decreasing the amount of certain end compounds of protein metabolism, such as phenols, indoles and putrefactive amines, linked to causing intestinal damage, also contributes to the healthy state of the pets’ intestines.
- Activates the immune system: Prebiotics are known to have the ability to modulate the functioning and response of the immune system of animals. Inulin increases the phagocytic capacity of macrophages. The addition of fermentable fibers to the diet of dogs and cats increases the number of Peyer’s patches, modulates the type and function of lymphoid tissue associated with the intestine, and increases the number of leukocytes and lymphocytes in the intestinal mucosa. FOS has been shown to increase the intestinal concentration of Immunoglobulin A, produced by B lymphocytes in the presence of antigens in the intestine. Ig A is important for mucosal immunity as it inhibits the adhesion and penetration of pathogenic bacteria and their toxins, increases the production of protective mucin and prevents inflammatory processes that can damage tissues.
- Protects the intestine against pathogenic bacteria: This action is produced by different mechanisms: decrease in intestinal pH due to accumulation of lactate produced by Lactobacillus and bifidobacteria; increased concentration of a peptide (bacteriocin type) secreted by bifidobacteria that directly inhibits pathogenic bacteria, among others.
- Reduce stool bad odor: the addition of FOS to the diet of animals reduces the intestinal concentration of compounds resulting from the rotting process that are associated with the generation of bad odor in the fecal matter. In general, fructans inhibit both the synthesis of the final products of protein fermentation (indoles, phenols, ammonia, volatile sulfur compounds, aromatic amines, etc.) and the growth of the bacterial population that generates them.
The presence of prebiotics, such as FOS and Inulin, in the balanced food consumed by dogs and cats nourishes and favors the normal functioning of intestinal cells, reinforcing the natural defense mechanisms of the body.
These attributes are important to maintain the health of animals in general and, above all, in those most vulnerable from the immunological point of view, such as puppies, kittens, pets in the mature stage or those that are subjected to some stress factor.