Prebiotics and Probiotics: Banking on Synergism

Egged on by prebiotics’ stimulative effects on probiotics and emerging research on the benefits conferred by a healthy gut flora, manufacturers have aimed to parlay the relationship into a whole new category of functional food: the “synbiotic.” While no official definition for such products yet exists, “when both probiotic cultures and prebiotics are added to foods, the two work in synergy and are referred to as synbiotic,” says Joe O’Neill, executive vice president of sales and marketing, Beneo-Orafti, Morris Plains, NJ. “The concept of synbiotic foods developed in Europe and was used as an opportunity to differentiate and market cultured dairy products.”

Synergist or additive?

The category is still in its infancy, both in terms of public awareness and scientific acceptance. The main question remains whether or not the interaction between probiotics and prebiotics in a single food is truly synergistic—as in more than the sum of its parts.

Mary Ellen Sanders, a consultant in probiotic microbiology with Dairy & Food Culture Technologies, Centennial, CO, and executive director of the International Scientific Association for Probiotics and Prebiotics (ISAPP), Davis, CA, isn’t so sure. “I have not seen strong evidence of that,” she says. “What we see sometimes are additive effects—you have a probiotic alone, a prebiotic alone, you put them together, and you get more than each by itself. But you don’t necessarily get more than the sum total.”

Researchers continue to look for the synergies, however, and O’Neill is bullish on their prospects. “For instance, studies have shown that prebiotics exert a stabilizing and protective impact on probiotics in products from manufacturing through shelf life all the way to the digestive tract,” he says. In one study, researchers supplemented Lactobacillus rhamnosus or Lactobacillus casei yogurts with 3% oligofructose in two forms. They tested the products at 10-week intervals for culture viability during shelf life, while also using a model in vitro digestive system to determine viability after consumption. Results showed that, at 10 weeks, both forms of oligofructose displayed a protective effect on the probiotics with no change in viability. The prebiotic yogurt processed through in vitro digestion showed no significant difference in L. rhamnosus cell counts, compared with a 36% decrease in the control, and the prebiotic L. casei yogurt saw a 5% decrease in culture viability after in vitro digestion, versus a 19% decrease in the control. The conclusion, O’Neill says, is that the prebiotics “protect probiotics during both storage and digestion.”

Supporting the benefits

Perhaps more intriguing is how synbiotic foods protect us. Puzzling out those benefits is the goal of the SYNCAN Program, an EU-funded research project that brings together scientists from six different countries to test the hypothesis that prebitoics and probiotics in combination protect the gut from the DNA changes that trigger colon cancer. One study looked at patients treated for colon cancer, as well as healthy subjects who had intestinal polyps removed. The subjects received either a placebo or a daily synbiotic supplement combining an Orafti prebiotic with two probiotic cultures. After 12 weeks, the subjects in the synbiotic group saw reductions in colon-cancer risk markers, normalization of cell turnover, and a 60% decrease in mucosal DNA damage, with risk reduction particularly strong in the polyp patients. “The dramatic risk reduction seen in the synbiotic group coincided with changes to the composition of gut bacteria that favored protective species, such as Bifidobacterium and Lactobacillus,” O’Neill adds. “These changes happened within a few weeks, showing that synbiotics can deliver immediate, as well as long-term, benefits.”

Though the jury may be out on synbiotics’ staying power, manufacturers are working on formulations while they wait for a consensus. The key points to keep in mind are that the synbiotic combination should suit the application, the dosage should be effective and tolerable, and the whole getup should stay stable during and after processing.

Continued market development of prebiotic- and probiotic-containing foods will require solid science to keep consumers curious and convinced. The need for clinical evidence is even greater with respect to synbiotics, an emerging category that attempts to “synergize” the benefits of probiotics and prebiotics in a single food. “The biggest challenge to selling probiotics continues to be education of the consumers with real facts,” says Terri Rexroat, global product manager, lactic cultures, Cargill Texturizing Solutions, Minneapolis. To sustain current momentum, both product developers and their consumers need to know what they’re giving, and what they’re getting.

Kimberly J. Decker, a California-based technical writer, has a B.S. in Consumer Food Science with a minor in English from the University of California, Davis. She lives in the San Francisco Bay area, where she enjoys eating and writing about food. You can reach her at [email protected].