The term 'gut health' is increasingly used as a catch-all phrase by many stakeholders, including scientists, health-care professionals, industry and the general public, to describe a wide range of health-related concepts. Despite its widespread use, particularly in relation to studies on diet, fermented foods, biotics and the gut microbiome, it remains unclear what the term gut health means. Therefore, an expert panel was convened by the International Scientific Association for Probiotics and Prebiotics to address the current state of scientific and clinical knowledge on the physiology, manifestation, application and measurement of the concept of gut health.

This study evaluates the efficacy of the postbiotic Probio-Eco in alleviating constipation in humans and mice. A randomized, double-blind, placebo-controlled crossover trial involving 110 adults with chronic constipation (Rome IV criteria) demonstrates that a 3-week Probio-Eco intervention significantly improves constipation symptoms, stool straining, and worry scores. Gut microbiota and metabolomic analyses reveal modulations in specific gut microbiota, succinate, tryptophan derivatives, deoxycholate, propionate, butyrate, and cortisol, correlating with symptom relief. A loperamide-induced mouse model confirms that Probio-Eco and its bioactive components (succinate, 3-indoleacrylic acid, and 5-hydroxytryptophan) alleviate constipation by stimulating mucin-2 secretion, regulating intestinal transport hormones, and promoting anti-inflammatory responses. Multi-omics integration identifies key pathways, including succinate-short-chain fatty acid, tryptophan-5-hydroxytryptophan-serotonin, and tryptophan-3-indoleacrylic acid, driving intestinal homeostasis and motility.

There is a lack of clinical data to support the effectiveness and safety of postbiotics in the modulation of human oral microbiota and oral health care. Here, volunteers were recruited and randomly assigned to two cohorts: a placebo group (n = 15) and a postbiotic group (n = 16). The placebo group used toothpaste that did not contain postbiotics, while the postbiotic group used toothpaste with postbiotics (3 x 10(10) CFU inactivated Lactobacillus salivarius LS97, L. paracasei LC86, and L. acidophilus LA85). Saliva samples were collected at different time points and the immunoglobulin A (IgA) and short-chain fatty acid (SCFA) levels were determined, while the salivary microbiota was analyzed by 16S rRNA amplicon sequencing. The results showed that salivary IgA levels and acetic and propionic acid levels were notably higher in the postbiotic group (P < 0.05), accompanied by an increase in the level of alpha diversity of the salivary microbiota, and these indexes remained high 1 month after discontinuing the use of toothpaste with or without postbiotics. A notable decrease in the relative abundance of the unclassified_Enterobacteriaceae, Klebsiella, Escherichia, etc. in the postbiotic group was accompanied by a notable increase in Ruminofilibacter and Lactobacillus. However, both groups did not cause significant changes in the overall structure of the host salivary microbiota. In conclusion, postbiotics dramatically and consistently improved oral immunity levels and SCFA content in the host. In addition, postbiotics were able to increase the level of microbial alpha diversity and down-regulate the abundance of some harmful microbes without significantly altering the structure of the host salivary microbiota. Chinese Clinical Trial Registry (ChiCTR) ( www.chictr.org.cn ) under the registration number ChiCTR2300074088.