Fucoidans, known for their diverse biological properties such as anti-inflammatory, antiviral, antitumor, and immune stimulatory effects, have recently gained attention for their potential benefits in exercise endurance, muscle mass, and anti-fatigue. However, the mechanisms by which fucoidans enhance exercise performance are still unclear. To investigate these effects, we administered 400 mg/kg/day of fucoidan extract derived from Undaria pinnatifida to 64 C57BL/6J mice over 10 weeks. We evaluated changes in running activity, mitochondrial-related gene expression in skeletal muscle, and alterations in the intestinal microbiome. Our results showed that fucoidan supplementation significantly increased daily running distance and muscle mass by 25.5% and 10.4%, respectively, in mice on a standard chow diet, and with more modest effects observed in those on a high-fat diet (HFD). Additionally, fucoidan supplementation led to a significant increase in beneficial gut bacteria, including Bacteroides/Prevotella, Akkermansia muciniphila, and Lactobacillus, along with a notable reduction in the Firmicutes/Bacteroidetes ratio, indicating improved gut microbiome health. Mechanistically, fucoidan supplementation upregulated the mRNA expression of key genes related to mitochondrial biogenesis and oxidative capacity, such as COX4, MYH1, PGC-1α, PPAR-γ, and IGF1, in both standard chow and HFD-fed mice. Our findings suggest that fucoidan supplementation enhances exercise performance, improves muscle function, and positively modulates the gut microbiome in mice, regardless of diet. These effects may be attributed to fucoidans’ potential prebiotic role, promoting the abundance of beneficial gut bacteria and contributing to enhanced exercise performance, increased muscle strength, and improved recovery.

Undaria pinnatifida fucoidan (UPF), a sulphated polysaccharide derived from brown seaweed, has attracted scientific and clinical interest for its wide-ranging anti-inflammatory and neurodegenerative properties. A growing body of research shows that UPF inhibits NF-κB and MAPK signalling pathways, reduces pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), decreases ROS production, and suppresses iNOS and COX-2 activity, thereby mitigating oxidative and inflammatory damage in vitro. In vivo studies confirm these actions, demonstrating reduced systemic inflammation, promoted antioxidant defence, modulated gut microbiota composition, and improved production of beneficial microbial metabolites. In parallel, emerging evidence highlights UPF’s neuroprotective potential, characterised by protection against neuroinflammation and oxidative stress, the attenuation of amyloid-beta deposition, and improvement in neuronal function. Importantly, low- to medium-molecular-weight and highly sulphated UPF fractions consistently exhibit stronger bioactivities, suggesting a structural basis for its therapeutic potential. This review integrates mechanistic evidence from cellular, preclinical, and emerging clinical studies, highlighting UPF as a versatile marine-derived agent with therapeutic relevance for inflammatory and neurodegenerative diseases, and outlines future research directions toward clinical translation.

Undaria pinnatifida fucoidan (UPF), a bioactive sulphated polysaccharide, is widely recognised for its anti-inflammatory, antioxidant, antitumor, anticoagulant, antiviral, and immunomodulatory properties. However, the precise mechanisms by which UPF regulates inflammation and neuronal health remain unclear. This study aimed to investigate the effects of UPF supplementation on pro-inflammatory cytokines in skeletal muscle, small intestine, and the hypothalamus, as well as plasma cytokine levels. Additionally, a brain proteomic investigation in the nucleus accumbens (NAc) was performed to assess UPF’s impact on neuronal protein expression in mice. A total of 64 C57BL/6J mice were administered either a standard chow or high-fat diet (HFD) with or without UPF (400 mg/kg/day) for 10 weeks. In HFD-fed mice, UPF significantly reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in skeletal muscle, small intestine, and hypothalamus, while also lowering circulating IL-1α and IL-6 levels. Proteomic analysis of the NAc revealed that UPF modulated proteins involved in oxidative stress, neuroinflammation, neurotransmitter regulation, and endoplasmic reticulum stress. In contrast, in chow-fed mice, UPF had no effect on the neuroinflammatory–oxidative stress markers but influenced the abundance of proteins associated with immune response and innate immunity. These findings suggest that UPF modulates stress-response pathways in a diet-dependent manner, supporting its potential neuroprotective role in inflammation-related disorders and brain health.

Fucoidans have demonstrated a wide range of bioactivities including immune modulation and benefits in gut health. To gain a deeper understanding on the effects of fucoidan from Undaria pinnatifida (UPF) on the colonic microbiome, the short-term Simulator of the Human Intestinal Microbial Ecosystem^®, a validated in vitro gut model, was applied. Following a three-week intervention period on adult faecal samples from three healthy donors, microbial community activity of the colonic microbiota was assessed by quantifying short-chain fatty acids while composition was analysed utilising 16S-targeted Illumina sequencing. Metagenomic data were used to describe changes in community structure. To assess the secretion of cytokines, co-culture experiments using Caco-2 and THP1-Blue™ cells were performed. UPF supplementation over a three-week period had a profound butyrogenic effect while also enriching colonic microbial diversity, consistently stimulating saccharolytic genera, and reducing genera linked with potentially negative health effects in both regions of the colon. Mild immune modulatory effects of UPF were also observed. Colonic fermentation of UPF showed anti-inflammatory properties by inducing the secretion of the anti-inflammatory cytokines IL-6 and IL-10 in two out of three donors in the proximal and distal colon. In conclusion, UPF supplementation may provide significant gut health benefits.

Fucoidans, known for their diverse biological properties such as anti-inflammatory, antiviral, antitumor, and immune-stimulatory effects, have recently gained attention for their potential benefits in exercise endurance, muscle mass, and anti-fatigue. However, the mechanisms by which fucoidans enhance exercise performance are still unclear. To investigate these effects, we administered 400 mg/kg/day of fucoidan extract derived from Undaria pinnatifida to sixty-four C57BL/6J mice over ten weeks. We evaluated changes in running activity, mitochondrial-related gene expression in skeletal muscle, and alterations in the intestinal microbiome. Our results showed that fucoidan supplementation significantly increased daily running distance and muscle mass by 25.5% and 10.4%, respectively, in mice on a standard chow diet, and with more modest effects observed in those on a high-fat diet (HFD). Additionally, fucoidan supplementation led to a significant increase in beneficial gut bacteria, including Bacteroides/Prevotella, Akkermansia muciniphila, and Lactobacillus, along with a notable reduction in the Firmicutes/Bacteroidetes ratio, indicating improved gut microbiome health. Mechanistically, fucoidan supplementation upregulated the mRNA expression of key genes related to mitochondrial biogenesis and oxidative capacity, such as COX4, MYH1, PGC-1α, PPAR-γ, and IGF1, in both standard chow and HFD-fed mice. Our findings suggest that fucoidan supplementation enhances exercise performance, improves muscle function, and positively modulates the gut microbiome in mice, regardless of diet. These effects may be attributed to fucoidans' potential prebiotic role, promoting the abundance of beneficial gut bacteria and contributing to enhanced exercise performance, increased muscle strength, and improved recovery.

Undaria pinnatifida fucoidan (UPF), a sulphated polysaccharide derived from brown seaweed, has attracted increasing scientific interest for its wide-ranging anti-inflammatory and neuroprotective properties. Previous studies have demonstrated that UPF exerts significant anti-inflammatory effects through the downregulation of pro-inflammatory cytokines, inhibition of key signalling pathways such as NF-κB and MAPKs, suppression of oxidative stress, and modulation of immune mediators and gut microbiota. In parallel, emerging evidence highlights UPF's neuroprotective potential, characterised by reduced neuroinflammation, oxidative damage, and amyloid-beta accumulation, alongside enhanced antioxidant defence and neuronal function. Current investigations reinforce these findings, suggesting that UPF may serve as a valuable adjunct in managing inflammation-related disorders and neurodegenerative conditions. This review summarises the current knowledge on UPF’s mechanisms of action, with a particular focus on its anti-inflammatory and neuroprotective pathways and implications for brain health, while also identifying gaps for future research and clinical translation.