Experts propose new synbiotics definition to broaden scope

25 Aug 2020 --- A new definition of synbiotics – a combination of pre- and probiotics – has been put forward by an expert panel from the International Scientific Association for Prebiotics and Probiotics (ISAPP). In a paper, the authors propose that the new definition is “a mixture comprising live microorganisms and substrate(s) selectively utilized by host microorganisms that confers a health benefit on the host.” The ISAPP panel emphasizes that the definition is designed to be inclusive and extends beyond the gut to include all parts of the body that harbor a community of microorganisms. 

“Creating a definition of synbiotic is a first step,” says Mary Ellen Sanders, ISAPP’s Executive Science Officer. “From here, the scientific community can focus on designing and carrying out studies to test the health effects of these products.”

“We hope the publication of this definition will mark a shift in people's understanding of synbiotics,” says author Kelly Swanson, Professor in the Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois at Urbana-Champaign in the SU.

“We can begin discussing synbiotics in a more scientifically accurate way, giving everyone a shared vocabulary for understanding what they do, how they work and what evidence is needed to meet the definition.”

Symbiosis of experts
The ISAPP panel meeting took place last May and the panel of 11 scientists sought to create a consensus definition and to clarify the evidence required to show synbiotics are safe and effective. The results have been published in Nature Reviews Gastroenterology & Hepatology.

The group also makes a distinction between “complementary synbiotics” and “synergistic synbiotics.”The word “synbiotic” appears on a growing number of food and supplement products, with synbiotic ingredients showing promise for modulating the community of microbes living in the human gut, while providing a health benefit. Synbiotics are generally understood to be a combination of a probiotic and a prebiotic – but experts have deemed this description too limiting for innovation in this field and too ambiguous to allow for a clear understanding of synbiotic health benefits.

In the publication, the group also makes a distinction between “complementary synbiotics,” in which a probiotic and prebiotic are combined but work separately, and “synergistic synbiotics,” in which the selectively utilized substrate specifically feeds the microorganisms that accompany it.

“Surveys indicate that consumers increasingly look for evidence that products on the market provide the benefits they claim to provide. Sanders says: “We expect that the scientific data on synbiotic health benefits will increase over time, alongside an increase in general awareness about synbiotics.”

A winning combination
The terms “prebiotic” and “probiotic” have their own definitions and standards. By omitting those specific terms from the definition of synbiotic, the expert panel says it allows for the use of microorganisms and selectively utilized substrates that may work together to elicit a health benefit but may not fit the definitions of pre- and probiotics when administered independently.

“The old definition of synbiotic included pre- and probiotics, which may have restricted innovation,” explains Hannah Holscher, panel member and an assistant professor in the Department of Food Science and Human Nutrition at Illinois.

Pre- and probiotics can still be combined under the new definition, as long as they’re tested together and shown to still provide positive, if not necessarily related, health outcomes. For example, a prebiotic might aid in digestive health while a probiotic may boost immunity after a flu vaccine. As long as they still provide those benefits in the host, they can be considered complementary synbiotics, Holscher says.

“The key there is testing. Even if the pre- and probiotics work separately, there could be some antagonism when put together. So really, they need to be tested together – in the target animal or human. We don’t want companies just randomly throwing things together,” Swanson notes.

In contrast, the ingredients in synergistic synbiotics are additive, working together to produce a single, targeted health benefit. These are most likely to be made with novel ingredients not already categorized under the current definitions of pre- and probiotics.

“In synergistic synbiotics, the substrate would support probiotic survival,” Holscher details. “For example, providing an energy source for the probiotic or changing the microbiome to support the survival of the probiotic.”

However, before plunging into the new supplements, the researchers advise consumers to consult with medical professionals to choose the right product for their specific needs.

“Just because there's a pre-, pro-, or synbiotic on the market, that doesn’t mean they’ll work across the board from infants to adults to geriatrics – from heart disease to gastrointestinal health. They’re all really there for a specific purpose,” Swanson says.

Holscher also adds that the question is not whether one should take a pre-, pro- or synbiotic. The question is, “what do you need those products to do?”

“We know a lot about the specific health outcomes of these products, so it’s a matter of finding what you need, rather than thinking of them as a blanket cure-all,” she concludes.

Edited by Kristiana Lalou