Prebiotics, which increase the in vivo growth rate or activity of probiotic bacteria like Lactobacillus and/or Bifidobacterium, are generally soluble fiber sources. Probiotics with or without prebiotics are fed to humans or animals to support intestinal health. Soluble fiber prebiotics are not digested by host animal digestive enzymes but rather, are the energy source for the probiotic species and are digested by enzymes produced by the probiotic species. Soluble fiber prebiotics enhance probiotic growth but are not required for growth.
There are some compounds that are semi-strict requirements for Lactobacillus and Bifidobacterium growth but that are not required for human or animal nutrition and which can serve as prebiotics. One such compound is polysorbate 80 that is contained in Lactobacilli MRS Broth (Difco Laboratories, Detroit, Mich.). When Lactobacilli or certain strains of Bifidobacteria are inoculated into this broth (containing 0.1% polysorbate 80) prolific growth results; whereas, in the absence of polysorbate 80, growth can be several logarithms lower. The inability of many individuals to experience the benefits of probiotic supplements may relate to the inability of probiotic strains to grow and colonize effectively in the absence of polysorbate 80.
The scientific literature reports that the oleic acid moieties in polysorbate 80 may provide its stimulating effect (See: Williams, W. L. et al, 1947, J. Biol. Chem., 170, 619-630). However, most probiotic strains are sensitive to the concentration of oleic acid in their growth media and respond negatively by producing less lactic acid (which is vital to obtaining strong probiotic benefits) when slight excesses of oleic acid are present. But these same strains do not respond negatively when excess polysorbate 80 is present. So it appears there is something unique to the polysorbate 80 stimulation effect, which oleic acid alone cannot duplicate.
The problems with using polysorbate 80 in commercial probiotic products when attempting to utilize its dramatic growth enhancing benefits are: 1) it is not a natural compound and is rejected by those consumers insisting on natural, organic ingredients; and 2) it reacts with and degrades freeze-dried probiotic strains when mixed directly with them. So, there is a need for an alternative natural prebiotic that can replace polysorbate 80 in commercial probiotic formulations, without the drawbacks mentioned above.