Stability comparison
Stability has always been one of the most important problems confronting probiotics. Probiotics are living microorganisms that should be viable during storage, transport, and consumption to be effective in the body. However, probiotics easily lose their viability at room temperature and can be largely destroyed by stomach acid and bile; hence, very few strains reach the gut and work effectively. Various studies have indicated that less than 50% of the bacteria in commercially available probiotic products are still active, meaning most probiotics stop working even before reaching the gut.
One experiment even showed that the survival rate of probiotics after treatment with stomach acid was only about 30%, meaning most of the probiotics taken by customers are destroyed in the stomach, with only a very few reaching the gut to function well. This kind of instability deeply lowers the actual efficacy of probiotics. Therefore, to make probiotics more stable, manufacturers need to employ encapsulation techniques and special freeze-drying processes, which has become a trend. In fact, these very same processes raise the cost of such products.
On the other hand, postbiotics are metabolic end-products resulting from the fermentation and metabolic action of probiotics, without live bacterial components. For this reason, postbiotics are not affected by external environmental conditions like temperature and pH; hence, they are more stable. Because postbiotics do not rely on the survival of active strains, they can keep the active ingredients stable during storage, and when they need to pass through digestive environments such as stomach acid and bile, they remain chemically intact and biologically active.
This also means that postbiotics are not greatly affected by different storage conditions and varying temperatures; hence, they are more suitable for use under disparate environmental conditions. Therefore, regarding stability, the advantages of postbiotics over probiotics are more obvious.
Health effects differences
The most direct role of probiotics in health effects is to regulate gut microbiota, repress harmful bacteria growth, and promote the proliferation of beneficial bacteria. By balancing the structure of gut microbiota, probiotics can prevent gastrointestinal diseases such as diarrhea, constipation, and irritable bowel syndrome to some extent and improve the immune function of the body. In a clinical trial involving more than 300 cases, it was documented that the incidence of diarrhea was reduced by about 30% through regular intake of certain kinds of probiotics.
However, not every population has been found to benefit in terms of health from the use of probiotics. The effectiveness of probiotics is very much dependent upon the current state of an individual’s gut microbiota, and different individuals have quite different compositions of gut microbiota. That, in turn, results in considerable variation in the probiotic effects among different populations. For instance, in some populations where the imbalance of gut microbiota is severe, supplementation with only probiotics cannot achieve the desired effect; it may even aggravate gut microbiota imbalances.
In contrast, postbiotics exert health effects directly through their biological activity, making their effects more pronounced. Examples of postbiotics include short-chain fatty acids like butyrate and propionate and cell wall components such as lipopolysaccharides, which can act directly on intestinal epithelial cells and immune cells. For example, butyrate is capable of promoting the repair and regeneration of intestinal epithelial cells and has strong anti-inflammatory effects. It has also been shown in studies that supplementation with butyrate decreases the intestinal inflammation response in patients with certain inflammatory bowel diseases by over 40%, something hardly achievable with probiotics alone.
Further, postbiotics have been shown to modulate the gut nervous system, thereby improving mood and sleep. Indeed, it was reported in one study that regular supplementation with postbiotics resulted in anxiety and depression symptoms reduced by 25% compared to the placebo group, thus indicating that even in emotional and mental health, postbiotics present positive effects.
In summary, postbiotics have more direct and stable influences on health, whereas probiotics are better suited for long-term regulation of the gut microbiota. For specific conditions that require rapid intervention, such as acute inflammation or immune modulation, postbiotics would be more suitable. For those conditions that require long-term management of the gut microbiota, for example, in patients suffering from chronic constipation or dysbiosis, probiotics will be better.
Adaptability to individual differences
The effect of probiotics is greatly influenced by individual differences, since gut microbiota composition has a significant impact on the colonization and proliferation of probiotics. For example, in individuals with relatively healthy gut microbiota, probiotics might easily colonize the gut and quickly perform their regulatory functions. However, in hosts with very imbalanced or low levels of gut microbiota, probiotics often are at a disadvantage in colonization and might be suppressed or excluded by harmful bacteria in the gut, which grossly diminishes their effectiveness.
Unlike probiotics, postbiotics are mainly fermentation and metabolic chemical products, including short-chain fatty acids and cell wall components, which act directly on gut cells or immune cells, independent of the gut microbiota status. Hence, individual variability in health effects is smaller with postbiotics, meaning that postbiotics can elicit similar biological activities inside the body regardless of the composition of gut microbiota in each individual.
In a study conducted on 20 patients with gut dysbiosis, postbiotic intervention resulted in significant improvement in gut health in 90% of the patients. This is in comparison with about 60% of patients using probiotic interventions under the same conditions. This means that under complex gut microbiota conditions or with large individual differences in health status, postbiotics can be said to be more adaptive and stable.
Immunomodulation advantages
Probiotics modulate the gut microbiota balance, which indirectly affects the gut immune cells. The addition of probiotics might allow for enhanced secretion of some anti-inflammatory cytokines and lower expression of pro-inflammatory cytokines, leading to decreased inflammation and promotion of gut health. This indirect immunomodulation, however, is greatly affected by the status of the individual’s microbiota and requires a longer time course for manifestation. In a six-month clinical trial, a 20% clinical improvement in anti-inflammatory immune response was observed among patients who took specific probiotics on a regular basis, but there were almost no significant changes during the first three months of the trial.
On the other hand, postbiotics, such as short-chain fatty acids like butyrate, directly interact with gut immune cells, thereby inducing the quick secretion of anti-inflammatory cytokines and reducing the release of pro-inflammatory cytokines. This direct action mechanism makes postbiotics more effective in anti-inflammatory and immunomodulatory functions. An experimental study showed that in patients using butyrate for intestinal inflammation treatment, inflammation markers such as CRP decreased by more than 30% within just 4 weeks, while such effects took over 3 months to appear in patients using probiotic intervention.
Moreover, certain types of postbiotic metabolites, such as lipopolysaccharides, may directly bind with Toll-like receptors on gut immune cells, which in turn triggers a cascade of immune signaling pathways to rapidly augment gut mucosal immune responses. This direct mode of action does not exist with probiotics, and therefore, in conditions where urgent intervention is required, such as in acute inflammation or immune deficiency, postbiotics are more effective.
