Marine-Algal-Derived Postbiotics Modulating the Gut Microbiota-Adipose Tissue Axis in Obesity: A New Frontier

Background: Obesity is increasingly recognized as a metabolic disorder driven by gut microbiota dysbiosis and chronic low-grade inflammation within adipose tissue. Emerging evidence highlights the gut-adipose tissue axis as a critical mediator of energy balance and metabolic regulation. Marine algae-rich in polysaccharides, polyphenols, and carotenoids-offer bioactive compounds that modulate gut microbial composition and generate beneficial metabolites termed "postbiotics." Objective: This review aims to comprehensively summarize current advances in understanding how marine-algal-derived postbiotics influence the gut microbiota-adipose tissue axis and contribute to obesity prevention and management. Methods: A structured literature search was conducted across PubMed, Scopus, Web of Science, ScienceDirect, and SpringerLink for studies published between 2015 and October 2025. Eligible studies included in vitro, in vivo, and human trials examining the effects of marine-algal compounds on gut microbiota composition, short-chain fatty acid (SCFA) production, adipose inflammation, and metabolic outcomes. Results: Marine-algal polysaccharides (fucoidan, alginate, laminarin, carrageenan, and ulvan) act as fermentable fibers that enhance SCFA production and enrich beneficial taxa such as Akkermansia, Lactobacillus, and Bacteroides, while reducing endotoxin-producing bacteria. Polyphenols and carotenoids (fucoxanthin, phlorotannins, astaxanthin) directly target adipogenesis, oxidative stress, and adipose browning. Animal studies consistently demonstrate reduced body weight, improved insulin sensitivity, and decreased inflammation following algae supplementation. Human trials-though limited-confirm safety and show microbiota modulation with modest weight loss. Conclusions: Marine-algal-derived postbiotics represent a promising, natural, and sustainable strategy to target the gut microbiota-adipose tissue axis in obesity. They offer multi-targeted mechanisms through microbial and host pathways, supporting their integration into functional food and nutraceutical development. Further clinical research and regulatory standardization are warranted to translate these findings into evidence-based interventions.