Review: Postbiotics show promise, even if method of action is unclear
A team of researchers from Wageningen University in the Netherlands as well as experts associated with Danone-Nutricia Research conducted a review of recent studies done on postbiotics. Their review paper is titled Postbiotics and Their Potential Applications in Early Life Nutrition and Beyond and was published in the International Journal of Molecular Sciences.
What does ‘postbiotics’ mean?
They noted that the term itself is not well defined, and could be expanded to mean, “[M]any different constituents including metabolites, short-chain fatty acids (SCFAs), microbial cell fractions, functional proteins, extracellular polysaccharides (EPS), cell lysates, teichoic acid, peptidoglycan-derived muropeptides and pili-type structures.”
To narrow this field, the authors proposed the following working definition: “Postbiotics are bioactive compounds produced by food-grade micro-organisms during a fermentation process. Postbiotics include microbial cells, cell constituents and metabolites.”
The authors noted that the term ‘postbiotics’ is a relatively new one, yet interest in the field is already high and is increasing. The curve for the number of studies appearing on postbiotics mimics that of their predecessors, prebiotics and probiotics. The number of studies done with these terms in the title have shown a rising curve and hit almost 3,700 last year.
Interest is accelerating rapidly
Postbiotics studies are a drop in the bucket by comparison, but are accelerating. From 1986, the first year with a study using that term in the title, the field bumped along with a smattering of studies each year, averaging less than three studies a year and never more than five in one year. Then in 2013, 11 such studies were published and there were 25 last year. It’s a small data set, but the rate of increase seems even faster than what was exhibited in the pre- and probiotics realm.
The authors noted that when postbiotics (paraprobiotics, a term coined to refer to heat-killed microorganisms, is also used) are administered with their fermentation medium, the effects can be similar to a probiotic intervention. It’s true that when a probiotic is administered and the intervention is successful, generally an increase in the population of that particular organism or organisms will be observed. But the metabolites of those organisms, upon which many of the observed health benefits are presumed to rest, will be similar in both cases.
And not having to worry about viability can confer some advantages, the authors noted.
“Postbiotics circumvent the technical challenge of colonization efficiency and keeping the microorganisms viable and stable in the product at a high dose. This facilitates delivering the active ingredients at the desired location in the intestine, improves shelf-life, and may simplify packaging and transport,” they noted.
Studies in children, adults show promise
In their review of studies on infants and young children, the authors included products that more generally resemble a dietary supplement delivery form as well as studies that used fermented infant formulas, or FIFs, which they said usually contain few if any viable microorganisms, whether because pasteurization or for other reasons.
The studies that used postbiotics or FIFs generally looked at endpoints such as stool consistency, the length of crying episodes related to gut discomfort, the prevalence of and recovery from diarrhea, etc. Some studies also administered a postbiotic in connection with a prebiotic (both fructooligosaccharide and galactooligosaccharide were mentioned).
The diarrhea effects in infants and toddlers were mild (generally shaving one day off of the duration of symptoms). But the results were mixed, too, leading researchers to conclude that this intervention might not be beneficial in all cases.
The studies done in adults used stool consistency and frequency measures and added measures of intestinal pain as well as the effect of the intervention on dermatitis.
Potential for benefit warrants more research
Taken together, the authors said the trend of general research is definitely in favor of doing more studies on postbiotics, given the promise they have shown thus far.
“In conclusion, postbiotics may contribute to the improvement of host health, even though the exact mechanisms have not been fully elucidated. In addition to mechanism of action focused preclinical and in vitro studies, well-designed randomized placebo-controlled intervention studies are needed to demonstrate health effects of postbiotics. . . . Postbiotics can be an elegant and safe method to improve health as postbiotics have less challenges compared to viable probiotics in terms of storage and shelf-life. Moreover, as shown in this review, several studies show comparable results for the viable probiotic and the postbiotic product,” the authors concluded.
Source: International Journal of Molecular Sciences
Postbiotics and Their Potential Applications in Early Life Nutrition and Beyond
Authors: Wegh CAM et al.