1. What is a prebiotic?
A prebiotic is a nondigestible food component that has a beneficial effect. Traditionally, food ingredients were only considered
useful if they contained nutrients that could be directly digested and absorbed by the gastrointestinal (GI) tract. In contrast,
nondigestible food ingredients, now collectively termed dietary fiber, were not considered nutritionally useful.
Over the last two decades, the importance of the GI microbiota (the collection of all GI microorganisms) on GI and overall
health has been recognized. Prebiotics, such as fructooligosaccharides or mannanoligosaccharides, serve as the main substrate
source for beneficial bacterial species of the GI microbiota and, thus, have a great impact on the GI microbiota and, in turn,
GI and overall health.
2. How can prebiotics exert health benefits?
The GI microbiota is made up of various bacterial species, including some potentially pathogenic bacteria. Prebiotics support
the expansion of some of the beneficial species of the physiologic bacterial ecosystem in the GI tract.
More specifically, prebiotic fiber is fermented by many beneficial species of the intestinal bacterial ecosystem, which leads
to the generation of short chain fatty acids. These short chain fatty acids then serve as an important energy substrate for
intestinal mucosal cells, which, in turn, leads to intestinal mucosal growth, increased GI motility, a decrease in pathogenic
bacterial species, an anti-inflammatory state of the GI mucosa, and the modulation of the gut-associated immune system.
3. What beneficial effects can veterinarians or consumers expect with prebiotic use?
Signs of GI disease are extremely common in both dogs and cats. In some patients, these clinical signs can be caused by specific
pathogenic bacteria, such as Salmonella species, or specific pathogenic strains of Campylobacter species. However, in many patients, no specific pathogenic bacteria can be identified. Yet, many of these patients will respond
to an antibiotic trial and, thus, are believed to have an alteration of the intestinal bacterial ecosystem. This syndrome
has been termed small intestinal bacterial overgrowth or antibiotic-responsive diarrhea. Many dogs and cats with an inflammatory infiltration of the GI mucosa also have alterations of their GI bacterial ecosystem
and also respond to antibiotic trials.
Traditionally, antibiotic therapy was the only treatment option for dogs with small intestinal bacterial overgrowth. However,
in a recent clinical trial, dogs supplemented with a prebiotic responded as well as dogs treated with an antibiotic.1 Furthermore, while many dogs treated with the antibiotic relapsed after completing the treatment, the dogs receiving the
prebiotic did not. This study demonstrates that not only can prebiotics be used as an alternative to antibiotic therapy in
dogs and cats with GI disease, but they may actually be superior in some of these patients since they can be continued long-term
and, thus, prevent a clinical relapse.
4. Is there any advantage to administering a prebiotic and a probiotic together?
Probiotics are live bacteria that are part of the physiologic intestinal bacterial ecosystem that when administered to a patient
convey a health benefit. In other words, probiotics are the same bacterial species that are specifically supported by prebiotics.
Thus, using a combination of a prebiotic and a probiotic can be advantageous since the prebiotic may provide an optimal set
of conditions in the GI tract to maximize survival, proliferation, and adherence of the probiotic in the GI tract. A prebiotic
may enhance or even potentiate the beneficial effects of a probiotic. When a balanced combination of a prebiotic and a probiotic
are used together, such a preparation is also known as a synbiotic. However, probiotics and prebiotics do not have to be administered in one formulation for health benefits to be potentiated.
In some instances, the prebiotic is supplied by use of a special pet food, while the probiotic is added by administering a
dietary supplement. ?
1. Ruaux CG, Tetrick MA, Steiner JM, et al. Fecal consistency and volume in dogs with suspected small intestinal bacterial
overgrowth receiving broad spectrum antibiotic therapy or dietary fructo-oligosaccharide supplementation. J Vet Int Med 2004;18:425 [abstract].