IngredientsCostaria costata (C. Agardh) De A. Saunders is a brown macroalga (phylum Ochrophyta, class Phaeophyceae) in the order Laminariales and the monotypic family Costariaceae. The species was formally named Costaria costata (C. Agardh) De A. Saunders, 1895. Its earliest basionym is Laminaria costata C. Agardh, 1817, and a number of other synonyms have been applied over the centuries, including Fucus costatus Turner, 1819; Costaria turneri Greville, 1830; Agarum quinquecostatum Bory, 1826; Costaria mertensii J. Agardh, 1848; Costaria quadrinervia Ruprecht, 1852; and Agarum costatum (C. Agardh) Dumortier, 1822.
The genus name derives from the Latin costa (rib), referring to its defining anatomical feature. It is distinguished by five ribs running the full length of the blade — three projecting on one surface and two on the opposing surface — and consists of a hapteral holdfast, an unbranched stipe, and a single undivided blade. Sporangial thalli are usually 1.5–2 m tall when mature, occasionally reaching 3 m, and are dark chocolate brown in colour; stipes may reach 50 cm and blades 35 cm in breadth.
The species is common on rocks in the lower intertidal to subtidal zone, ranging from northern Japan and Alaska (Shumagin Islands) to San Pedro, California. Although sometimes described as an annual, it is distributed from Alaska to southern California in the low intertidal and upper subtidal regions, and displays a range of morphological shapes reflecting local wave exposure. Beyond the North Pacific coast of North America, Costaria costata is also a seaweed commonly found in coastal Asia. It has been used as edible seaweed for a long time in Japan and as a nutritious foodstuff for abalone (Haliotis spp.). In recent years, C. costata has been successfully introduced to the coast of Dalian in northern China for captive breeding.
Common names in English include five-rib kelp and ribbed kelp. The species is classified within the broader category of "kombu-type" kelps alongside Saccharina japonica and Undaria pinnatifida in East Asian commercial contexts.
In Asia, seaweed has long been recognised to exhibit various functions. In traditional Chinese medicine, seaweed is widely known to exert biological activities, such as anticancer effects, and is available as pills for consumption. Among brown algae, Fucus vesiculosus, Undaria pinnatifida, and Costaria costata, which are widely distributed along the coasts of China and Asia, have been used in traditional Chinese medicine.
The thalli of kelps have popularly been used as traditional vegetables and herbal drugs. Among the commercial kelps studied for functional lipids — including Saccharina japonica, Undaria pinnatifida, and Costaria costata — the gametophyte phases have received less attention compared to the sporophyte thalli traditionally consumed.
C. costata has been used as edible seaweed for a long time in Japan and as a nutritious foodstuff for Abalone (Haliotis spp.). Macroalgae have been used for nutritional and medicinal purposes in many cultures throughout history and are an important part of traditional diets, especially in Asian countries. The specific edible use of C. costata in Japan parallels the broader East Asian tradition of consuming laminarian kelps as foods and tonic medicines, though the available literature does not document detailed preparation methods or specific traditional indications for C. costata separately from related species such as S. japonica.
Scientific study of C. costata has intensified in recent years, mainly because this alga contains unique and abundant biologically active substances and sulfated fucan. Previous research has shown that its dietary fiber has significant hypolipidemic effects.
A study analyzing variations in chemical composition of C. costata during the harvest period reported the following ranges: moisture (4.94–10.50%), ash (29.25–38.19%), protein (9.77–18.15%), lipid (0.60–2.21%), crude fiber (4.45–5.68%), alginate (22.49–29.13%), fucoxanthin (0.07–0.32 mg g⁻¹), and polyphenol (1.579–4.796 mg g⁻¹).
Polysaccharides in brown algae are present mainly in the form of fucan, with some alginate and laminarin also present. Fucans extracted from marine sources are called fucoidans, which are composed mainly of L-fucose and sulfate groups.
The structural chemistry of C. costata fucoidan is notably complex and changes with the season. Seasonal variations of the polysaccharide composition were studied, and it was found that the alga synthesizes in April–May a high-molecular-weight (200–800 kDa) low-sulfated heterofucan, and in July primarily a low-molecular-weight (20–300 kDa) sulfated and acetylated galactofucan. A small amount (<0.01% of total alga mass) of laminaran (1,3;1,6-β-D-glucan) is present in mature alga.
Two key structural studies provide detail on monosaccharide composition. A 2011 study isolated fucoidan from C. costata collected near Korean coasts and characterised the fucoidan from E. cava as a mixture of sulfated rhamnogalactofucan and galactofucan, while fucoidan from C. costata was identified as a sulfated galactofucan. A 2023 study from the Chinese Academy of Sciences found that C. costata polysaccharide (CCP) consists of galactose and fucose as the main monosaccharides with a sulfate group content of 18.54%. A 2026 study characterising a fucoidan preparation from C. costata harvested near Dalian, China, reported that glucose was the most abundant monosaccharide at 56.2%, followed by fucose at 28.4%; other monosaccharides included mannose (6.2%), galactose (6.0%), xylose (1.9%), and rhamnose (0.9%). Differences in monosaccharide profiles between studies reflect variation by geographic origin, season, and extraction method.
Seasonal timing significantly affects fucoidan content: the fucoidan content of C. costata increases with growth, with the highest content obtained in the month of June, after which it starts to decrease. The contents of fucose and SO₃Na (sulfonate groups) also follow a similar trend, with the highest yields obtained from samples collected in June. Fucoidan content reaches its maximum in June, with substantial changes in molecular weight distribution, monosaccharide composition, and sulfate content occurring simultaneously; the fraction of fucose in the polysaccharides decreases significantly from June to July, while that of mannose increases.
C. costata contains a significant complement of phlorotannins, marine-specific polyphenols unique to brown algae. The aqueous ethanol extract of Costaria costata contains abundant phlorotannins with antitumour potential; phlorotannins from the same species were also found to be effective inhibitors of fucoidanase. A specific high-molecular-weight phlorethol fraction (CcPh, Mw = 2520 Da) has been isolated and characterised for pharmacological activity.
The composition and properties of alginate from C. costata vary during the life of the alga. Alginate harvested in May and June has a higher molecular weight, viscosity, and proportion of mannuronic acid, whereas that harvested in July has a lower molecular weight and viscosity but a higher proportion of guluronic acid.
As a member of the Laminariales, C. costata contains the xanthophyll carotenoid fucoxanthin. Measured concentrations in harvested thalli range from 0.07 to 0.32 mg g⁻¹ dry weight depending on harvest timing. Brown macroalgae are rich in various bioactive compounds such as fucoxanthin, phlorotannin, fucoidan, alginate, and laminarin, which have antioxidant, anti-inflammatory, antidiabetic, anticancer, and antihypertensive effects and may also exhibit immunoregulating or neuroprotective properties.
For commercial kelps including Costaria costata, total lipid contents in the gametophyte phase were almost twice those of the thallus; kelp species, life stage, and gender were critical factors affecting lipid accumulation. The gametophyte phases of U. pinnatifida and C. costata were rich in essential fatty acids C18:2 n−6 and C18:3 n−3.
A distinct protein compound — not a polysaccharide — has also been isolated: a direct-acting antithrombotic serine protease (designated CCP) was purified from brown seaweed Costaria costata, characterised as a monomeric protease with a molecular mass of 60,547.598 daltons as determined by mass spectrometry.
The immune regulatory effect of C. costata fucoidan (FCC) was examined using bone marrow-derived dendritic cells (BMDCs). Pretreatment with FCC dose-dependently decreased lipopolysaccharide (LPS)-induced upregulation of co-stimulatory molecules and major histocompatibility complex. FCC prevented morphological changes in LPS-induced BMDCs and suppressed the secretion of pro-inflammatory cytokines. Importantly, treatment of BMDCs with FCC alone did not increase the levels of IL-1β, IL-6, IL-12, and TNF-α in the culture medium, indicating that FCC did not induce activation of BMDCs on its own.
C. costata polysaccharide (CCP) was found to resist TGF-β1-induced epithelial-mesenchymal transition (EMT) in A549 cells by inhibiting the TGF-β/Smad and PI3K/AKT/mTOR signalling pathways.
Fucoidan components from Costaria costata showed antioxidative and immunomodulatory properties. The effective rate was determined to be 10 mg/mL of fucoidan crude extract for scavenging activity, and results showed better activity against hydroxyl radicals (OH·). In a rodent model, antioxidant activities of Costaria costata extract inhibited oxidative stress in the liver of CCl₄-induced mice by increasing expression of superoxide dismutase (SOD) and reducing the malonaldehyde level.
Anticoagulant and FGF-1, -2, -7, -8, -9, -10/FGFR1c signalling activation activities of C. costata polysaccharides were examined. Studies showed that the polysaccharides were sulfated at different positions of galactose and fucose residues. APTT-, PT- and TT-based anticoagulant assay results indicated that high molecular weight and a higher degree of sulfation were essential for anticoagulant activities. This finding is consistent with broader fucoidan literature: high molecular weight was essential for the anticoagulant activity of polysaccharides from Costaria costata.
The C. costata serine protease (CCP) exhibited high amidolytic activity toward substrate S-2251. Fibrin plate and fibrin zymography results revealed that CCP was able to degrade fibrin clots directly, specifically hydrolysing Aα and Bβ chains followed by γ chains of human fibrinogen and fibrin.
Fucoidans are sulfated fucosylated polymers from brown algae cell walls. The inhibitory effects of Costaria costata fucoidan on UVB-induced MMP-1 promoter, mRNA, and protein expression were assessed in vitro using the immortalised human keratinocyte (HaCaT) cell line. Pretreatment with fucoidan significantly inhibited MMP-1 protein expression compared to UVB irradiation alone. Fucoidan significantly reduced MMP-1 mRNA expression and inhibited UVB-induced MMP-1 promoter activity by 37.3%, 53.3%, and 58.5% at 0.01, 0.1, and 1 μg/mL, respectively.
High molecular weight (HMW) fucoidans are known to bind to growth factors, such as fibroblast growth factors (FGFs), and protect them from proteolysis. Studies on C. costata polysaccharide fractions examined their ability to activate FGF-1, -2, -7, -8, -9, and -10 signalling through FGFR1c in BaF3 cells, finding that molecular weight and sulfation degree were key determinants of activity.
In vitro and animal evidence (preliminary): A study extracted fucoidan from Costaria costata and examined its anti-inflammatory effect. Using LPS-stimulated BMDCs in vitro, pretreatment with FCC dose-dependently decreased LPS-induced upregulation of co-stimulatory molecules and major histocompatibility complex; FCC prevented morphological changes in LPS-induced BMDCs; and treatment with FCC suppressed secretion of pro-inflammatory cytokines. In an in vivo mouse model, oral administration of FCC suppressed LPS-induced lung inflammation, reducing the secretion of pro-inflammatory cytokines in the bronchoalveolar lavage fluid, and the administration of FCC suppressed LPS-induced sepsis. This study was conducted in mice; no human clinical data are available.
Animal evidence (preliminary): A 2026 study published in the International Journal of Biological Macromolecules investigated C. costata fucoidan in a murine ulcerative colitis model. FCC from C. costata, which suppresses LPS-induced sepsis and lung inflammation by inhibiting dendritic cell activation, was investigated in a mouse model of ulcerative colitis (UC). Orally administered FCC significantly inhibited UC severity induced by dextran sulfate sodium (DSS) intake; FCC administration decreased the infiltration of T cells and neutrophils into the colon of DSS-treated mice. Furthermore, FCC suppressed DSS-induced production of interferon-gamma (IFN-γ) and interleukin 17 (IL-17) in colonic T cells; however, FCC did not directly suppress IFN-γ and IL-17 production in CD4 T cells. This is preclinical mouse data only; no human trials are available.
In vitro evidence (preliminary): Fucoidans were isolated by water extraction and ion-exchange chromatography from brown algae including Costaria costata collected near Korean coasts, and their structures were investigated. Fucoidan from C. costata was characterised as a sulfated galactofucan. Fucoidan isolated from S. hornery was separated into three fractions, while the results clearly showed that fucoidans play an inhibitory role in colony formation in human melanoma and colon cancer cells and may be effective antitumour agents. This is in vitro colony formation data; no in vivo or human data are specifically available from this study for the C. costata fraction.
Regarding phlorotannins: The anticancer and radiosensitising effects of high-molecular-weight phlorethols (CcPh, Mw = 2520 Da) isolated from Costaria costata were investigated on human colorectal carcinoma HCT 116 and HT-29 cells. Phlorethols CcPh possessed cytotoxic activity against HT-29 (IC₅₀ = 92 μg/mL) and HCT 116 (IC₅₀ = 94 μg/mL) cells. CcPh at non-toxic concentrations inhibited colony formation in colon cancer cells and significantly enhanced their sensitivity to low non-toxic X-ray irradiation. The combinatory effect of radiation and CcPh was synergistic (Combination Index < 0.7). The authors concluded that algal phlorethols might be prospective candidates as radiosensitisers to improve the scheme of radiotherapy. All data are from in vitro cell-line experiments; no animal or human evidence has been reported.
Animal evidence (preliminary): A study published in Carbohydrate Polymers (2014) structurally characterised the fucoidan from C. costata and examined its hepatoprotective effects. Antioxidant activities of Costaria costata extract inhibited oxidative stress in the liver of CCl₄-induced mice by increasing the expression of superoxide dismutase (SOD) and reducing the malonaldehyde level. These findings are from a rodent model of chemically induced liver injury; no human data are available.
In vitro and animal evidence (preliminary): A 2023 study (PMC10254178), authored by researchers at the Chinese Academy of Sciences, isolated a fucoidan (CCP) from C. costata and assessed it in both cell and mouse models of idiopathic pulmonary fibrosis (IPF). A fucoidan from Costaria costata was isolated and its anti-idiopathic fibrosis activity was investigated both in vitro and in vivo; chemical composition analysis showed that the polysaccharide consists of galactose and fucose as the main monosaccharides with a sulfate group content of 18.54%. CCP resisted TGF-β1-induced epithelial-mesenchymal transition in A549 cells by inhibiting the TGF-β/Smad and PI3K/AKT/mTOR signalling pathways; in vivo study found that CCP treatment alleviated bleomycin-stimulated fibrosis and inflammation in mice lung tissue, suggesting that CCP could protect the lung from fibrosis by relieving the EMT process and inflammation in lung cells. No human clinical trials exist for this indication.
In vitro / biochemical evidence (preliminary): Crude polysaccharides from Costaria costata were extracted by hot water and fractionated by anion exchange chromatography; three low-molecular-weight fragments were prepared by degradation. Structural features were elucidated based on HGPC, FT-IR, NMR, MS, and monosaccharide composition analyses. Studies showed that the polysaccharides were sulfated at different positions of galactose and fucose residues, and that high molecular weight and a higher degree of sulfation were essential for anticoagulant activities. Separately, a direct-acting fibrinolytic enzyme (serine protease) was identified: a direct-acting antithrombotic serine protease (CCP) was purified from C. costata, characterised as a monomeric protease with molecular mass of 60,547.598 daltons; it exhibited high amidolytic activity and fibrin zymography revealed it was able to degrade fibrin clots directly, specifically hydrolysing fibrinogen and fibrin chains. All evidence is from in vitro biochemical or cell studies; no human trials exist.
In vitro evidence (preliminary): The inhibitory effects of Costaria costata fucoidan on UVB-induced MMP-1 promoter, mRNA, and protein expression were assessed in vitro using the immortalised human keratinocyte (HaCaT) cell line. Pretreatment with fucoidan significantly inhibited MMP-1 protein expression compared to UVB irradiation alone; fucoidan significantly reduced MMP-1 mRNA expression and inhibited UVB-induced MMP-1 promoter activity by 37.3%, 53.3%, and 58.5% at 0.01, 0.1, and 1 μg/mL, respectively. The authors concluded that C. costata fucoidan may be a potential therapeutic agent to prevent and treat skin photoaging. This is in vitro cell-line data only.
Preliminary evidence: The study of C. costata has intensified in recent years, mainly because this alga contains unique and abundant biologically active substances and sulfated fucan; previous research has shown that its dietary fiber has significant hypolipidemic effects. These references are cited in the literature but based on preclinical models. No human clinical trials have been reported for this specific indication.
In vitro evidence (preliminary): Anticoagulant and FGF-1, -2, -7, -8, -9, -10/FGFR1c signalling activation activities of C. costata polysaccharide fractions in BaF3 cells were examined. The interaction of highly sulfated polysaccharides with fibroblast growth factors has been studied as a potential avenue for tissue repair or angiogenesis modulation, though this remains at the biochemical/cell stage with no clinical translation yet reported for C. costata.
No standardised human clinical dosages have been established for Costaria costata or its extracts. The following dosages have been reported in preclinical experimental contexts only:
All dosages cited are from in vitro or animal research and cannot be extrapolated to human supplementation without dedicated pharmacokinetic and clinical data, which do not currently exist in the published record for C. costata.
Current evidence is primarily based on in vitro or animal studies, and more rigorous human research is required to confirm efficacy and safety as a nutritional ingredient. No formal toxicology studies, adverse event reports, or clinical safety trials specific to C. costata extracts have been identified in the peer-reviewed literature at this time.
APTT-, PT- and TT-based anticoagulant assay results indicated that high molecular weight and a higher degree of sulfation were essential for the anticoagulant activities of C. costata polysaccharides. Because fucoidan-rich extracts from C. costata possess demonstrated in vitro anticoagulant properties, concurrent use with anticoagulant or antiplatelet pharmaceuticals (e.g., warfarin, heparin, aspirin, direct oral anticoagulants) represents a theoretical interaction concern. Additionally, the purified serine protease from C. costata was able to degrade fibrin clots directly, hydrolysing fibrinogen and fibrin chains — a profile that raises further considerations in coagulation-relevant contexts.
As a member of the Laminariales — the same order as Saccharina japonica (kombu) — C. costata likely accumulates significant quantities of iodine as part of its high ash content (29.25–38.19% dry weight). Excess iodine intake from kelp consumption is a recognised concern in individuals with thyroid disorders, particularly those with pre-existing autoimmune thyroid disease or iodine sensitivity, though no specific iodine content measurements for C. costata were identified in the studies retrieved.
The structure and function of fucoidan vary according to the species of brown algae and extraction techniques. Specimens from different geographic locations such as the Dalian coast in northern China were expected to have different structural characteristics and thus different biological activities and medicinal effects, because their cultivation and habitat can induce variations in chemical composition and structure. This means that the pharmacological properties documented in research extracts may not translate directly to commercial preparations derived from different sources or at different seasons.
The totality of the pharmacological evidence base for C. costata is preclinical. There are very few studies on the bioavailability and mechanisms of nutrients, phenolics, and flavonoids in macroalgae. Since the metabolic transformations of these metabolites in humans are overlooked, their effects on health are also unclear. More in vivo and clinical studies are needed on the potential use of brown macroalgae in the field of health.
Health conditions that Costaria costata may help support.
Body systems that Costaria costata may help support.
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