Food scientists have long tried to solve this with encapsulation, wrapping sensitive molecules in protective carriers that shield them in the stomach and release them further down the line. Gel-based delivery systems have emerged as a leading strategy, but most of them share a common flaw. They typically rely on differential swelling: the gel swells more in the intestine than in the stomach, allowing some cargo to escape. The problem is that the matrix itself often survives the intestinal stage largely intact, trapping a substantial fraction of the anthocyanins inside. Previous systems built from gelatin and gellan gum, or from peptides and whey protein isolate, achieved respectable but incomplete release, leaving a meaningful portion of the payload locked away in a structure that never fully fell apart.

A research team led by Wenjun Li and colleagues has now reported a solution in Food Chemistry: X that hinges on an unusual ingredient from the sea: fucoidan, a sulfated polysaccharide extracted from brown seaweeds. The key insight lies in electrostatics. In an earlier study, the group had built gelatin-pectin gels in which pectin’s carboxyl groups, with a pKa of roughly 3.5, flip from mostly uncharged in the acidic stomach to strongly negatively charged in the near-neutral intestine. That charge shift drove electrostatic repulsion and partial network collapse, releasing about 80 percent of the encapsulated anthocyanins. Impressive, but not complete. Fucoidan offered something better: its sulfate ester groups carry pKa values of only about 0.5 to 2.0, meaning they remain aggressively anionic across virtually the entire gastrointestinal pH range.

The team’s hypothesis was elegant. Gelatin, a protein derived from collagen, carries a positive charge under strongly acidic conditions. Pair it with fucoidan in the stomach, and the opposite charges attract, compensating one another and locking the network into a stable, self-supporting gel. Shift to intestinal pH, however, and fucoidan’s sulfate groups become massively negative while gelatin’s positive charge fades. The once-balanced composite turns strongly anionic, electrostatic repulsion takes over, and the network destabilizes, potentially disintegrating so thoroughly that nearly all of the anthocyanins are freed. To test this, the researchers prepared a systematic matrix of 25 formulations, varying total solid content from 2 to 10 percent and the gelatin-to-fucoidan mass ratio from 9:1 down to 5:5.

The characterization work revealed clear rules of composition. Rheological measurements showed that all gel-forming formulations behaved as true elastic gels, with the storage modulus exceeding the loss modulus, and that stiffness climbed steadily with solid content. Hardness testing with a texture analyzer confirmed the same trend: more solids meant more internal crosslinking and greater mechanical strength. Scanning electron microscopy of a representative 10 percent gel revealed the porous, interconnected three-dimensional architecture that gives hydrogels their capacity to harbor small molecules. Not every combination worked, however. The 5:5 gelatin-fucoidan mixtures failed to form self-supporting gels at any solid content, and the 2 percent formulations were too soft to measure reliably, establishing that a sufficient gelatin fraction is essential to build the continuous network in the first place.

Encapsulation performance was striking across the board. Every stable gel-forming formulation captured more than 95 percent of the added anthocyanins, with the best result, 98.77 percent, achieved by the 10 percent gel at a 6:4 ratio. Fluorescence microscopy showed the pigments distributed uniformly throughout the matrix with no aggregation. Storage tests over 14 days demonstrated that encapsulated anthocyanins retained far more of their color and content than free anthocyanins, particularly under light exposure, where unprotected pigments degrade fastest. The gel was not just a delivery vehicle but also a preservative, extending the shelf-life stability of the compounds it carried.

The electrostatic story played out exactly as predicted. Zeta potential measurements showed that at pH 1.5, gelatin carried a positive charge of about +7 millivolts while fucoidan was mildly negative, and the composite sat near neutral at +2 millivolts, the signature of charge compensation. At pH 6.8, fucoidan plunged to −42.2 millivolts and the composite shifted to −20.6 millivolts, a distinctly anionic state primed for repulsion-driven collapse. Correspondingly, in simulated gastric fluid the gels swelled moderately but held their macroscopic shape for the full two-hour digestion, while in simulated intestinal fluid they dissolved dramatically, with the softest formulations vanishing within an hour. Control experiments at body temperature confirmed that the 10 percent composite gel remained self-supporting in gastric conditions yet disintegrated in intestinal fluid, showing the response was not merely an artifact of gelatin’s thermal softening.

The release data delivered the headline result. The standout formulation, containing 10 percent solids at an 8:2 gelatin-to-fucoidan ratio, leaked only 3.50 percent of its anthocyanins during the gastric stage, then released 99.94 percent of the total payload after intestinal exposure, essentially complete liberation within experimental error. Neighboring high-solid formulations at 9:1 and 7:3 ratios performed nearly as well, at 99.11 and 98.08 percent. For context, the team’s earlier gelatin-pectin system managed 87.87 percent intestinal release with 10.70 percent gastric leakage, and a dual-crosslinked apricot polysaccharide hydrogel reached about 87 percent cumulative release. The new system outperformed both benchmarks on gastric retention and intestinal delivery simultaneously, resolving the trade-off that had limited earlier designs.

Kinetic modeling added mechanistic texture to the findings. Fitting the release profile to five standard models showed that the Logistic model described the sigmoidal, stage-dependent behavior best, with an R-squared of 0.998, capturing the quiet gastric phase, the sharp surge after the pH transition, and the final plateau. The Ritger-Peppas exponent of about 1.07, though a weaker fit, pointed toward release governed by structural changes in the matrix rather than simple diffusion, consistent with the visual evidence of network disintegration coinciding with the release surge. Together, the kinetics and microscopy painted a coherent picture: anthocyanin liberation is driven not by passive swelling but by the active, pH-triggered dismantling of the gel network itself.

Beyond the immediate result, the study offers a design framework with broader implications. It demonstrates that the responsive element of a delivery gel can be tuned by choosing polysaccharides with different ionizable group chemistries, and that sulfate-rich marine polysaccharides deserve a central place in that toolkit. The composition rules matter too: more fucoidan is not automatically better, because the network-forming capacity of gelatin and the electrostatic responsiveness of fucoidan must be balanced. The authors note that the roles of digestive enzymes, bile components, and intestinal ions in modulating release still merit targeted investigation before such systems reach real foods. But the principle is now established: with the right polymer pairing and the right recipe, a food-grade gel can guard delicate plant pigments through the stomach’s acid bath and then dissolve almost completely where the body can actually use them.

Subject of Research: pH-responsive gelatin-fucoidan composite hydrogels for gastrointestinal delivery of anthocyanins

Article Title: Composition-guided design of Gelatin-fucoidan composite gels for gastric anthocyanin retention and intestinal release

Article References: Li, W., Li, J., Zeng, Q., Chen, W., Chen, X., Huang, Y., & Yang, W. (2026). Composition-guided design of Gelatin-fucoidan composite gels for gastric anthocyanin retention and intestinal release. Food Chemistry: X, 39, Article 104538. https://doi.org/10.1016/j.fochx.2026.104538

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104538

Keywords: anthocyanins, fucoidan, gelatin, hydrogels, drug delivery, bioavailability, pH-responsive, electrostatics, food chemistry, encapsulation, marine polysaccharides, simulated digestion

What makes marine carbohydrates so chemically interesting is their structural diversity. Polysaccharides extracted from seaweeds, sponges, shellfish and marine bacteria can carry sulfate groups in patterns that differ from species to species, form glycosidic linkages that are uncommon in terrestrial plants, and adopt branched architectures that change how they interact with biological targets. Fucoidans from brown algae, carrageenans from red algae, chitin and chitosan derivatives from crustacean shells, and sulfated glycosaminoglycan-like molecules from marine animals all fall into this category. Because the precise arrangement of sulfate groups and sugar units determines how these molecules bind to proteins, enzymes and cell surfaces, even subtle structural differences can translate into dramatically different biological effects.

That sensitivity to structure is precisely why these molecules have attracted attention across so many therapeutic areas. The review documents reported antiviral, anticoagulant, immunomodulatory and antitumor activities for marine-derived carbohydrates and their derivatives, alongside material properties that make them useful in drug delivery systems, wound dressings and tissue engineering scaffolds. Sulfated polysaccharides, for example, can interfere with viral attachment and entry by mimicking the charged surfaces that viruses normally latch onto, while alginate-based materials have become mainstays in encapsulation and wound-care applications because of their gentle gelling behavior and biocompatibility.

The clinical story of marine-inspired drugs is older than many readers might expect. The review’s authors anchor their timeline to cytarabine, an antileukemia drug approved in the United States in 1969, which traces its chemical inspiration to nucleosides originally isolated from a Caribbean sponge. Although cytarabine is not itself a carbohydrate in the polysaccharide sense, it established a crucial precedent: molecules derived from marine organisms could survive the full gauntlet of preclinical testing, regulatory scrutiny and clinical use. Later products built on alginate, carrageenan and other marine raw materials followed, extending the family of carbohydrate-based medicines into areas such as wound management, drug formulation and symptomatic treatment.

Today, the pipeline is broader than ever. The review surveys clinical-stage candidates derived from marine carbohydrates currently being evaluated for viral infections, cancer, metabolic disorders, tissue repair, cystic fibrosis and neurological disease. This breadth reflects both the versatility of the molecules and the maturity of the field: what was once a collection of exploratory extracts has become a portfolio of defined candidates moving through controlled trials. Yet the authors are careful to note that the distance between a promising laboratory result and an approved product remains substantial, and that the obstacles are not primarily about discovering new activities.

The central challenge, according to the review, is reproducibility. The biological activity of a marine polysaccharide depends on its molecular weight, its sulfation pattern and its monosaccharide composition, but all three of these parameters can vary with the species from which the material is harvested, the season in which it is collected, and the extraction and processing methods used to isolate it. A batch of fucoidan gathered from one coastline in spring may differ measurably from a batch of the nominally same polymer collected elsewhere in autumn. For a regulatory agency, such variability is a serious problem, because a drug must deliver the same molecule, with the same quality attributes, every single time.

Solving that problem requires the kind of systematic thinking that the review tries to encourage. The authors argue that marine carbohydrates have too often been studied in terms of individual biological activities, with each research group reporting a single effect in isolation, while clinical development demands an integrated understanding of how structure, production, quality control and mechanism of action fit together. A candidate cannot advance if researchers cannot define its composition precisely, manufacture it consistently and explain how it works at the molecular level. The review therefore treats approved drugs and clinical candidates not just as success stories, but as case studies in how these elements can be aligned.

The priorities for future development that the authors identify are correspondingly practical. They call for reliable production methods based on cultivation, fermentation or enzymatic processing, which would decouple drug supply from wild harvesting and reduce batch-to-batch variation. They emphasize the need for improved quality control that combines structural characterization with activity-based assays, so that manufacturers can verify not only what a batch contains but what it does. They also stress the importance of validating molecular targets and mechanisms of action, and of conducting more rigorous pharmacokinetic and safety studies, areas in which complex carbohydrates have historically lagged behind small-molecule drugs because of their size, heterogeneity and analytical difficulty.

Achieving these goals, the review concludes, will require collaboration across disciplines that do not always work together. Senior and co-corresponding author Guangli Yu of the Ocean University of China notes that progress will depend on close cooperation among researchers in glycoscience, analytical chemistry, synthetic biology, materials science and clinical research. Co-corresponding author Chao Cai, also of the Ocean University of China, shares responsibility for the work, which was conducted within the Key Laboratory of Marine Drugs under the Ministry of Education and the Shandong Key Laboratory of Glycoscience and Glycotherapeutics. The interdisciplinary framing is deliberate: no single field currently possesses all the tools needed to characterize, manufacture and clinically validate a heterogeneous natural polymer.

The significance of the review lies less in any single discovery than in its synthesis. By following a clinical timeline that stretches from a 1969 leukemia drug to today’s trials in virology, oncology, metabolic disease and neurology, it demonstrates that marine carbohydrate therapeutics are not a speculative frontier but an evolving branch of pharmacology with a documented track record. The structural uniqueness of ocean-derived sugars, once a curiosity, is now understood as a design resource, and the field’s remaining challenges are the familiar ones of manufacturing, characterization and clinical evidence. If the collaborative agenda the authors describe takes hold, the next chapters of this timeline may be written not by chance discoveries in tide pools, but by engineered production systems capable of delivering the ocean’s chemistry with pharmaceutical precision.

Subject of Research: Marine carbohydrate-based drug development and clinical translation

Article Title: Marine carbohydrate therapeutics: from structural diversity to clinical translation

Article References: Marine carbohydrate therapeutics: from structural diversity to clinical translation. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: marine carbohydrates, polysaccharides, fucoidan, alginate, carrageenan, drug development, clinical trials, glycoscience, sulfation, antiviral, anticoagulant, Ocean University of China

MASLD is no longer a niche concern. It encompasses a spectrum running from simple hepatic steatosis to the inflammatory, fibrotic condition known as metabolic dysfunction-associated steatohepatitis, and it is tightly coupled to obesity and type 2 diabetes. Treatment options remain frustratingly thin. The recent approval of resmetirom, a thyroid hormone receptor-beta agonist that became the first FDA-approved medication for nonalcoholic steatohepatitis, marked a genuine milestone, but clinicians still lack cheap, safe, preventive strategies for the vast population of patients with early disease. That gap has pushed researchers toward nutraceuticals—food-derived compounds with drug-like activity—and toward the gut microbiome as a therapeutic target in its own right.

The gut–liver axis sits at the center of the new review’s argument. The liver receives the portal blood supply directly from the intestine, along with everything the gut microbes produce: short-chain fatty acids, bile acid derivatives, trimethylamine N-oxide, indole compounds, endotoxins, and ethanol made by bacteria themselves. When the microbial community falls into dysbiosis—a state that clinical studies have repeatedly linked to the severity of fatty liver disease—the balance of these metabolites tips. Barrier function in the intestine weakens, bacterial lipopolysaccharide leaks into circulation, hepatic inflammation and oxidative stress escalate, and hepatocytes accumulate fat. Some evidence even implicates high-alcohol-producing Klebsiella pneumoniae in driving fatty liver in non-drinkers, underscoring how directly microbial chemistry can become hepatic pathology.

What makes marine polysaccharides different from the plant fibers already celebrated in nutrition? The authors emphasize structural chemistry. Land-based fibers are built largely from neutral sugars, whereas marine polysaccharides—fucoidans from brown seaweeds, carrageenans from red algae, ulvans from green algae, agars and porphyrans from Porphyra, alginates from kelp, chitosan from crustacean shells, and sulfated glycans from sea cucumbers—carry sulfate groups and uronic acids, form complex glycosidic linkages, adopt diverse conformations, and span broad molecular-weight distributions. Those features mean that human enzymes cannot digest them, but specific gut bacteria can, using elaborate carbohydrate-active enzyme systems called polysaccharide utilization loci. The result is selective feeding: particular structures recruit particular microbial taxa, shifting community composition in reproducible, mechanism-linked ways.

Human populations provide a striking natural experiment. Japanese individuals harbor gut bacteria that acquired genes for digesting marine sulfated polysaccharides from marine Bacteroides via horizontal gene transfer, a discovery that revealed how the microbiome can expand its metabolic repertoire when the diet supplies novel glycans. Subsequent genomic work identified multiple independent transfer events that seeded seaweed-digestion genes into human gut bacteria. This capacity for adaptation is precisely what marine polysaccharide therapy hopes to exploit: by supplying glycans that only beneficial consumers can process, these compounds act as targeted prebiotics, enriching organisms such as Lactobacillus, Akkermansia muciniphila, and beneficial Bacteroides species while suppressing inflammatory lineages.

The downstream metabolic consequences are where the review gets technically ambitious. Fermentation of marine polysaccharides yields short-chain fatty acids—acetate, propionate, and butyrate—which nourish colonocytes, strengthen tight junctions, and engage G-protein-coupled receptors that regulate glucose homeostasis and appetite. Simultaneously, polysaccharide-driven changes in bile acid metabolism alter signaling through the nuclear receptor FXR and the membrane receptor TGR5, pathways now recognized as central to hepatic lipid handling, energy expenditure, and inflammation. At the hepatocyte level, marine polysaccharides and their oligosaccharide fragments activate AMPK and PPARα, the master switches of fatty acid oxidation, and engage the Nrf2 antioxidant program, directly countering the lipid accumulation and oxidative stress that define steatohepatitis.

Preclinical evidence illustrates the breadth of this approach. Fucoidan from Sargassum fusiforme alleviated high-fat diet-induced obesity and insulin resistance while improving the gut microbiota profile and hepatic oxidative stress. Alginate oligosaccharides relieved insulin resistance and fatty liver in mice through microbiota-mediated bile acid regulation. Iota-carrageenan tetrasaccharide reduced liver lipid accumulation via the bile acid–FXR–SHP/PXR pathway, and chitosan oligosaccharides attenuated steatosis, inflammation, and oxidative stress in diet-induced obese mice. Sea cucumber fucosylated chondroitin sulfate modified gut microbiota to prevent obesity, and oyster polysaccharide ameliorated hepatic oxidative stress through the bile acid–FXR–AMPKα axis. Porphyran from discolored nori prevented metabolic syndrome through a microbiota–bile acid–ceramide pathway, while ulvan oligosaccharides regulated lipid metabolism in high-fat diet-fed animals.

Clinical data, though still early, are encouraging. A randomized, double-blinded, placebo-controlled trial found that chitosan supplementation improved liver function, hepatic steatosis predictors, and metabolic indicators in adults with non-alcoholic fatty liver disease. Chitooligosaccharides rebalanced gut microorganisms and their metabolites in NAFLD patients, and Icelandic trial data showed that chitosan supplementation favorably altered the gut microbiota in healthy women. A fucoidan extract improved insulin resistance and cardiometabolic markers in obese, nondiabetic subjects in a randomized controlled trial, and fucoidan has also demonstrated clinical efficacy as an adjunct in Helicobacter pylori eradication, hinting at broad microbiome-modulating potential. Trials combining Laminaria japonica with probiotics improved intestinal microbiota in human volunteers, and fecal microbiota transplantation protocols now being tested in steatohepatitis underscore how central microbial manipulation has become to the field.

The review is candid about the obstacles between laboratory promise and clinical reality. Marine polysaccharides are structurally heterogeneous, and batch-to-batch variation in sulfation pattern, molecular weight, and monosaccharide composition makes standardization difficult—yet those same variables appear to determine biological activity, as shown by recent synthetic fucoidan libraries that enabled systematic structure–function comparisons. Safety questions also persist, particularly for carrageenan, a widely used food additive whose degraded forms have been associated with intestinal inflammation in some animal and human studies, even as food-grade material appears benign in others; clarifying this controversy is essential for consumer confidence. Contaminant burdens in macroalgae, including arsenic, cadmium, lead, and mercury, require careful regulatory alignment between producing and consuming regions. Dosing, bioavailability, and long-term effects remain underexplored.

Nevertheless, the authors position marine polysaccharides as uniquely advantaged relative to terrestrial fibers: their unusual chemistries reach microbial niches that common fibers cannot, and their pleiotropic effects—spanning short-chain fatty acid production, bile acid signaling, barrier protection, endocrine modulation, and direct hepatic pathway activation—map precisely onto the multi-organ pathophysiology of MASLD. As sequencing technologies make it possible to identify exactly which bacteria consume which glycans, and as controlled synthesis enables reproducible materials, the field is converging on a rational design framework: engineer polysaccharide structures to recruit defined beneficial communities and thereby steer the gut–liver axis away from disease. If clinical trials confirm the early human signals, the humble slime of the seashore may prove to be one of the most practical liver medicines of the coming decade—harvested not from a pharmaceutical plant, but from the wrack line.

The scale of the unmet need gives this research agenda its urgency. Population studies suggest that roughly a third of adults in many industrialized countries carry hepatic steatosis, with prevalence climbing in children and adolescents, yet most affected individuals are identified only incidentally or through rising cardiometabolic risk factors. Because early-stage disease is largely asymptomatic, an intervention that could be delivered safely as a dietary supplement—and taken for years—would address a far larger population than any prescription drug realistically can.

The prebiotic framing deserves careful attention. Classic prebiotics such as inulin and fructooligosaccharides are fermented broadly by common saccharolytic organisms, which can limit how precisely a community can be steered. Sulfated marine glycans, by contrast, demand specialized enzyme machinery, so only microbes equipped with the appropriate sulfatases and carbohydrate-active enzymes can access them. This substrate specificity is the theoretical basis for precision microbiome editing through diet, and it explains why the authors treat structural chemistry rather than fiber content as the decisive design variable.

Molecular weight emerges as a recurring theme in the preclinical literature. High-molecular-weight polymers are often poorly soluble and difficult for microbes to process, while controlled depolymerization into oligosaccharides frequently enhances water solubility, bioactivity, and fermentability. Several of the most striking animal results cited in the review involve oligosaccharide fragments rather than intact polymers, suggesting that processing technology—enzymatic degradation, controlled hydrolysis, or even synthetic chemistry—will be as important as source selection for future products.

Practical considerations also favor the field. Many marine polysaccharides already hold food additive or generally recognized as safe status in major jurisdictions, and industrial supply chains for carrageenan, alginate, and agar are mature, which could shorten the path from bench to consumer. Seasonal and geographic variation in seaweed composition remains a genuine hurdle, but cultivation of defined macroalgal strains under controlled conditions offers a route to more consistent raw material than wild harvest alone.

What remains most persuasive is the convergence of mechanisms: microbial selection, metabolite generation, barrier reinforcement, and direct hepatic signaling all point in the same direction. Few nutraceutical candidates offer that degree of mechanistic coherence, and few target a disease with such a large and growing affected population.

Subject of Research: Marine polysaccharides as nutraceutical modulators of the gut microbiome and gut–liver axis in metabolic dysfunction-associated steatotic liver disease

Article Title: Marine polysaccharides: promising nutraceuticals for metabolic dysfunction-associated steatotic liver disease as unique and potent modulator of gut microbiome

Article References: Pan, Y., Zhang, R., & Chen, Y. (2026). Marine polysaccharides: promising nutraceuticals for metabolic dysfunction-associated steatotic liver disease as unique and potent modulator of gut microbiome. Food Science and Biotechnology. https://doi.org/10.1007/s10068-026-02283-w

Image Credits: AI Generated

DOI: 10.1007/s10068-026-02283-w

Keywords: marine polysaccharides, MASLD, gut microbiome, gut–liver axis, fucoidan, carrageenan, ulvan, chitosan, short-chain fatty acids, bile acid signaling, nutraceuticals, fatty liver disease