Ecklonia

Ecklonia cava: A Comprehensive Reference

1. Identity and Botanical Classification

Taxonomic and Chemical Names

Ecklonia cava Kjellman is the accepted scientific name for this species. Ecklonia is a genus of brown algae (Phaeophyceae) belonging to the order Laminariales. The species was formally classified within the family Lessoniaceae. Ecklonia cava (E. cava, Lessoniaceae) is an edible brown alga abundantly distributed along the coasts of Korea and Japan.

Common names and trade designations differ by region and context. In Japan, it is more commonly known as "kajima." Products are typically sold in pill form but may also be powdered; other names for this supplement include Alginol and Seanol.

Natural Source and Physical Description

Ecklonia cava is a perennial brown alga and exists mainly in subtidal areas off the coast of Japan and Korea, especially in kelp forests along the central Pacific coast in Honshu (Southern Bōsō Peninsula/Chiba Prefecture to Wakayama Prefecture), parts of the Seto Inland Sea, the southern coast along the Sea of Japan, and the coast in Kyushu. The waters off the coast of China, Japan, and Korea are more commonly associated with Ecklonia cava, but it also grows in the coastal waters of Australia, New Zealand, and South Africa.

Typically found in the Pacific Ocean, this alga thrives in underwater beds, ranging from 2 to 25 metres in depth and reaching heights of up to 1.30 metres. Each plant consists of one long stalk, usually 3 to 6 feet in length, with multiple blades growing from the stalk to form a single clump at the top, resembling a palm tree. Ecklonia cava grows in large underwater forests on rocky substrates near the shoreline.

Common Forms and Preparations

Ecklonia cava, described as an edible brown seaweed abundantly produced in Korea, has been widely used as an ingredient in food, animal feed, and fertilizers. As a dietary supplement, products are typically sold in pill form but may also be powdered. E. cava is also used as herbal medicine in the form of an extract called Seanol, which is high in phlorotannin. Extracts are characteristically standardized to phlorotannin content, and specifically to the marker compound dieckol. It is harvested (either mechanically or by divers) in Japan, Korea, and China.

2. Traditional and Historical Use

Much like other algae and seaweeds, Ecklonia cava has long been used as a traditional folk remedy in China, Japan, and Korea. For centuries, Ecklonia cava has been a staple in the diets of certain Asian communities, with historical use in Japanese soups dating back to the 4th century.

Archival documentation supports its antiquity in Japanese trade. This conclusion is derived from studies on wooden shipping tags (mokkan) from the 7th–8th centuries: the products labeled as arame (滑海藻/阿良女) are conjectured to have been E. cava or E. bicyclis, depending on the places of origin recorded on the tags. The products labeled as kajime/kachime (未滑海藻/加知女) were likely to signify pulverized forms of either seaweed, as explained in the Wamyō Ruijushō dictionary, which represents the word kajime as 搗布, literally meaning 'pounding cloth/seaweed'.

Though these seaweeds are attested to have been eaten in ancient times, the details of the culinary use are unknown, though it has been speculated that they were consumed as food in a manner similar to how they are used today. These seaweeds are usually preserved dried so as to retain sliminess after rehydrating, and they can be chopped up into miso soup to add sliminess; or, after removing the slime, they can be turned into simmered dishes (nimono).

In traditional medicine, it was used to treat goiters, hemorrhoids, urinary diseases, constipation, and stomach ailments. Because it provides iodine, calcium, and other nutrients, it has also served historically as a supplement for breastfeeding women. In traditional Korean and Japanese medicine, Ecklonia—particularly Ecklonia cava—has been utilized for its potential health benefits. Early herbalists used extracts of this seaweed to promote cardiovascular health, enhance immune function, and combat inflammation. Ancient texts mention its use in the form of broths and decoctions, which were believed to purify the blood and invigorate the body.

3. Key Constituents and Active Compounds

Phlorotannins: The Primary Bioactive Class

E. cava contains unique polyphenols called phlorotannins and is enriched with these phlorotannins compared to other brown algae. These polyphenolic compounds are exclusively synthesized through the polymerization of phloroglucinol units and are well-known for their exceptional antioxidant capacity and versatile bioactivities, positioning them as promising candidates for drug discovery and therapeutic development.

The phlorotannins dieckol, eckol, 6,6′-bieckol, phlorofucofuroeckol A, 7-phloroeckol, fucodiphloroethol G, and dioxinodehydroeckol can be isolated from E. cava and have a wide range of biological activities. Among the phlorotannins identified in Ecklonia species are eckol (a closed-chain trimer of phloroglucinol), phlorofucofuroeckol (a pentamer), and dieckol (a hexamer).

The antioxidative activities of all phlorotannins, except for phloroglucinol, were stronger than the polyphenols found in green tea.

Other Constituents

Additional constituents include sterols, including fucosterol, ergosterol, and cholesterol. The alga also contains fucoidan, a sulfated polysaccharide with its own range of documented biological activities. Minerals are present in the extract in relatively high concentrations including sodium (4,400 ± 800 mg/kg), calcium (4,800 ± 400 mg/kg), magnesium (1,300 ± 100 mg/kg), potassium (700 ± 200 mg/kg), and iodine (220 ± 40 mg/kg).

Pharmacokinetics

A dedicated pharmacokinetic study has examined the absorption and clearance of E. cava phlorotannins in rats. Intravenous administration at 10 mg/kg allowed detectability in plasma for up to 36 h for dieckol and 8,8′-bieckol, but only 2 h for PFF-A. Oral administration at doses of 100 mg/kg and 1,000 mg/kg showed limited detectability, indicating low bioavailability and rapid clearance, particularly for PFF-A. These findings have implications for optimizing dosing in humans, though human pharmacokinetic data remain limited.

4. Established Mechanisms of Action

Antioxidant Activity

Many studies in vitro and in vivo show that phlorotannins have various biological and pharmacological effects, including antioxidation, antitumor, antiobesity, antidiabetic, neuroprotective, and hepatoprotective activities. The phlorotannins of E. cava act as direct scavengers of reactive oxygen species (ROS). 7-Phloroeckol, 6,6′-bieckol, phloroglucinol, eckol, fucodiphloroethol A, and dieckol reportedly have antioxidant activities.

Anti-inflammatory Mechanisms

6,6′-Bieckol was shown to suppress the binding of nuclear factor kappa B (NF-κB) to tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6 promoters in macrophages. The expression of NF-κB-inducible cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) was also modulated.

GABAergic (Sedative-Hypnotic) Mechanism

The primary objective of early hypnotic research was to investigate whether seaweeds have hypnotic activity. Methanol extracts of 30 seaweeds were screened for their binding activity at the GABA type A-benzodiazepine (GABA_A-BZD) receptor, a well-characterised molecular target for sedative-hypnotics. The most active seaweed was Ecklonia cava Kjellman. Major phlorotannins of the ethyl acetate fraction with the highest activity were eckol, eckstolonol, dieckol, and triphlorethol-A, and their Ki (binding affinity, μM) values for [3H]-flumazenil binding were 1.070, 1.491, 3.072, and 4.419, respectively. Hypnotic effects of the extract and the ethyl acetate fraction were fully inhibited by flumazenil, a specific GABA_A-BZD receptor antagonist. These results imply that phlorotannins of E. cava induce sleep by positive allosteric modulation of the GABA_A-BZD receptor.

Angiotensin-Converting Enzyme (ACE) Inhibition

Inhibition of angiotensin I-converting enzyme (ACE) activity is the most common mechanism underlying the lowering of blood pressure. Five organic extracts of Ecklonia cava were prepared and tested for their potential ACE inhibitory activities. Five kinds of phlorotannins—phloroglucinol, triphlorethol-A, eckol, dieckol, and eckstolonol—were isolated from the ethanol extract of E. cava and exhibited potential ACE inhibition. Dieckol was the most potent ACE inhibitor and was found to be a non-competitive inhibitor against ACE according to Lineweaver-Burk plots. Dieckol also had an inducible effect on the production of nitric oxide (NO) in EAhy926 cells without having a cytotoxic effect.

α-Glucosidase and α-Amylase Inhibition (Glycemic Mechanisms)

8,8′-Bieckol and 2-O-(2,4,6-trihydroxyphenyl)-6,6′-bieckol showed α-glucosidase inhibitory activity at about 2.3 μM. Compounds inhibited the catalytic reaction of α-glucosidase in non-competitive and competitive manners, respectively. α-Glucosidase is an enzyme that plays a key role in raising blood sugar level and is considered a good target for developing drugs to treat type 2 diabetes.

An additional mechanism was demonstrated in an animal model: investigation of the effect of Ecklonia cava on intestinal glucose uptake found that intestinal Na⁺-dependent glucose uptake (SGU) and Na⁺-dependent glucose transporter 1 (SGLT1) protein expression was determined using brush border membrane vesicles (BBMVs), and glucose-induced insulin secretion was examined in pancreatic β-islet cells. Methanol extract of E. cava markedly inhibited intestinal SGU of BBMV with an IC50 value of 345 μg/mL. SGLT1 protein expression was dose-dependently down-regulated with E. cava treatment.

Anti-adiposity and Leptin Resistance Mechanisms

In one study evaluating the effects of Ecklonia cava extract (ECE) containing rich phlorotannins on inflammation and leptin resistance in the adipose tissue of a diet-induced obese model, effects on fat deposition, inflammation, M1/M2 macrophage, and T-cell infiltrations were investigated. ECE attenuated the expression of inflammation-related receptors such as TLR4 and RAGE and leptin resistance by reducing SOCS3 expression, increasing expression of leptin receptor in adipose tissue, and increasing lipolysis.

Tyrosinase Inhibition (Skin Pigmentation)

7-Phloroeckol is involved in the process of skin whitening, as it inhibits melanin biosynthesis in B16F10 melanoma cells. The inhibitory activity of seven phlorotannins from Ecklonia cava was tested against tyrosinase, which converts tyrosine into dihydroxyphenylalanine. Compounds 2-phloroeckol and 2-O-(2,4,6-trihydroxyphenyl)-6,6′-bieckol had IC50 values of 7.0 ± 0.2 and 8.8 ± 0.1 μM, respectively, in competitive mode.

Antiviral Mechanisms

Ecklonia cava produces phlorotannins that inhibit syncytia formation, lytic effects, and viral p24 antigen production both in vitro and in vivo. It has shown potent inhibition of HIV-1 reverse transcriptase enzyme. Phlorotannin components, which are oligomeric polyphenols of phloroglucinol units, are responsible for the pharmacological activities of E. cava; these compounds likely inhibit virus infection through blockage of viral attachment through inhibition of sialic acid (SA) binding to host cells, and/or prevention of viral replication through inhibition of viral RNA and protein synthesis.

5. Scientific Evidence by Health Area

5.1 Sleep Quality and Insomnia

This is among the most studied areas for E. cava in humans. The brown seaweed Ecklonia cava supplement containing phlorotannins has been approved by the Ministry of Food and Drug Safety (South Korea) as a health-functional ingredient that helps improve sleep quality. In Korea, Ecklonia cava ethanol extract is one of five functional food ingredients that have been granted a health claim for "may help to improve sleep quality."

Human evidence: In a randomized, double-blind, placebo-controlled trial, the effectiveness and safety of phlorotannins at a dose of 500 mg/day for 7 days in adults with self-reported sleep disturbances were investigated. 72 adults with sleep problems consumed Ecklonia cava extract (500 mg/day) or placebo for 4 weeks; the Ecklonia cava group reported reduced sleep latency, improved sleep efficiency, and enhanced subjective sleep quality. A clinical case study also demonstrated the effects of acupuncture therapy and the phlorotannin-rich E. cava extract (500 mg/day) on sleep disturbance in patients with amyotrophic lateral sclerosis (ALS); after 5 months of combined treatment, the Pittsburgh Sleep Quality Index (PSQI) score decreased from 13 to 8.

Preclinical evidence: An ethanol extract of E. cava (ECK-E) significantly potentiated pentobarbital-induced sleep in mice; in four solvent fractions separated from ECK-E, hypnotic activity was proportional to contents of total phenols and total phlorotannins.

Evidence strength: Research on Ecklonia cava's sleep effects is still in early stages. Most studies are small-scale or short-term, and large-scale, long-term clinical trials are lacking. Additional research is needed to definitively establish effectiveness. The regulatory recognition in South Korea is notable, but the evidence base behind this claim remains limited in scope.

5.2 Metabolic Health: Body Weight and Blood Lipids

Human clinical evidence: Ninety-seven overweight male and female adults (average age 40.5 ± 9.2 yr and BMI of 26.5 ± 1.6 kg/m²) were enrolled in a randomized, double-blind, placebo-controlled trial with parallel-group design. Subjects were randomly allocated into three groups designated as placebo (PC), low-dose (LD, 72 mg-ECP/day), and high-dose (HD, 144 mg-ECP/day). Both LD and HD groups showed significant decreases in BMI, body fat ratio, waist circumference, waist/hip ratio, total cholesterol, low-density lipoprotein (LDL) cholesterol, and total cholesterol/high-density lipoprotein (HDL) cholesterol.

A separate uncontrolled study examined E. cava phlorotannins in people with hypercholesterolemia. Lee et al. (2012) conducted an uncontrolled, open-label, single-arm study to assess the effect of Ecklonia cava phlorotannins in 52 individuals with hypercholesterolaemia (fasting total cholesterol > 240 mg/dL or LDL cholesterol > 130 mg/dL). The prevalence of hypertension and diabetes mellitus in the sample was 23.4% and 8.7%, respectively. All subjects consumed daily 400 mg of Ecklonia cava phlorotannins.

Evidence strength: The 12-week randomized, double-blind, placebo-controlled trial offers moderate-quality evidence for effects on lipid profiles and body composition parameters in overweight individuals. The open-label study carries greater risk of bias. The overall evidence base for lipid-lowering effects in humans is encouraging but limited by small sample sizes and a restricted number of independent trials.

5.3 Glycemic Control and Diabetes

Human clinical evidence: Lee et al. conducted a randomized clinical trial on 73 male and female participants with fasting blood glucose between 100 to 180 mg/dL. Participants were randomly divided into two groups given 500 mg of AG-dieckol three times a day for 12 weeks. The result shows an acute significant reduction in postprandial blood glucose (PPBG) (p < 0.05) after 12 weeks of intervention. However, a non-significant postprandial insulin level (PPIL) reduction was seen in the group who consumed AG-dieckol compared to the placebo group. Nonetheless, within-group reduction was significantly observed in terms of insulin level compared to baseline.

A separate study investigated the effect of polyphenolic-rich seaweed extract (Ecklonia cava) on postprandial blood glucose (PPBG) and postprandial insulin level (PPIL) in 20 prediabetic patients in Saudi Arabia. The double-blind, randomized-controlled trial was conducted from November 2020 to April 2021 in Riyadh. Subjects were given 600 mg of seaweed extract in a single dose for acute effect investigation.

Preclinical evidence: Fasting blood glucose concentrations were markedly decreased by E. cava supplementation in diabetic mice without any significant differences in normal mice. Plasma insulin concentrations were markedly reduced in diabetic mice, and E. cava supplementation significantly increased them.

Evidence strength: When these investigations were based on humans, few clinical studies failed to yield clear and consistent results. Human evidence is promising but derived from small trials with methodological limitations, including small sample sizes and heterogeneous populations. The preclinical evidence base is relatively robust, but direct extrapolation to humans requires caution.

5.4 Cardiovascular Health and Blood Pressure

Preclinical and mechanistic evidence: The ACE-inhibitory activity of dieckol and other phlorotannins, described in the mechanisms section above, provides a plausible pharmacological basis for antihypertensive effects. Pyrogallol-phloroglucinol-6,6′-bieckol (PPB) was selected to be orally administered in two mouse models: a diet-induced obese model and a diet-induced hypertension model. After four weeks of administration, the blood pressure of all mice was measured.

Evidence strength: Cardiovascular benefits, including antihypertensive effects, have primarily been demonstrated in animal models and in vitro systems. Human clinical evidence specifically targeting blood pressure as a primary outcome is very limited. The lipid-modulating effects observed in the Shin et al. (2012) trial are relevant to cardiovascular risk reduction, but causality for clinical endpoints has not been established.

5.5 Neuroprotection and Cognitive Function

Preclinical evidence: Multiple animal model studies have examined E. cava's potential in cognitive decline and neurodegeneration. One study investigated the neuroprotective effect of a 70% ethanol extract of Ecklonia cava (EE) in amyloid beta (Aβ)-induced cognitive deficit mice. The result showed that EE ameliorated learning and memory decline in behavioral tests on Aβ-induced mice. EE also attenuated oxidative stress by regulating malondialdehyde (MDA) content, reduced glutathione (GSH), and superoxide dismutase (SOD) levels.

EE enhanced synapse function by modulating acetylcholine-related enzymes and synaptic structural proteins in the whole brain, hippocampus, and cerebral cortex tissues. EE also regulated Aβ-induced apoptosis and inflammation through the c-Jun N-terminal kinase (JNK) and nuclear factor-kappa B (NF-κB) signaling pathways. Furthermore, EE protected neurotoxicity by increasing brain-derived neurotrophic factor (BDNF) production.

One study determined the effects of intake of polyphenols from Ecklonia cava on spatial task performance and nervous fatty acid composition in mice fed with a high-fat diet. Thirty mice were randomly divided into three groups: a control group fed 5% soybean oil, a high-fat (HF) group fed a 15% lard diet, and a polyphenol (ECP) group maintained on the HF diet plus 1% E. cava polyphenols. The ECP group exhibited a short escape latency and better memory retention in the Morris water maze test compared with the control and HF groups. Moreover, the consumption of polyphenols from E. cava was associated with higher levels of DHA in the brain and retina.

The neuroprotective effects of phlorotannin-rich extract from E. cava (ECPE) and dieckol decreased the production of pro-apoptotic proteins Bax and caspase-3, suggesting that ECPE and its main component dieckol prevent oxidative damage to neurons and inactivate their apoptotic processes.

Evidence strength: Neuroprotective evidence is entirely preclinical (animal models and cell cultures). Further properly designed clinical studies in animals and humans are needed to fully demonstrate the action of Ecklonia cava in the treatment of AD patients. In vivo animal studies and human clinical trials using phlorotannin-rich ECPE are warranted in the future. No human clinical trials specifically targeting cognitive outcomes have been conducted to date.

5.6 Athletic and Endurance Performance

Human evidence: A double-blind, placebo-controlled, crossover study was conducted by Oh et al. (2010) in order to assess an acute effect of (pre-exercise) Ecklonia cava phlorotannin supplementation on endurance performance in 20 male college students during highly intense exercise. Results from this study, as referenced in supplementary literature, indicated that a single dose of Ecklonia cava polyphenols significantly extended time to exhaustion during endurance exercise by over 2 minutes compared to placebo.

Evidence strength: This is a single crossover study with a small sample of 20 participants. The EFSA Panel noted that no conclusions can be drawn from this acute efficacy study for the purposes of a safety or broader efficacy assessment. The data are preliminary and insufficient to make firm conclusions about ergogenic effects.

5.7 Anti-obesity Effects

Preclinical evidence: ECE showed antiadiposity and anti-inflammatory effects, attenuated leptin resistance, and increased lipolysis in the diet-induced obese model. This study shows that ECE is a suitable dietary supplement candidate for the prevention or treatment of obesity or obesity-associated diseases, especially inflammation-related diseases.

E. cava extract has been reported to have antilipidemic and anti-obesity related effects both in vitro and in vivo study; most of the in vitro studies were performed on 3T3-L1 cells, and in vivo studies were performed on mice. In mice, dieckol and seapolynol isolated from E. cava have an antihyperlipidemic effect.

Evidence strength: Anti-obesity evidence is primarily preclinical. The Shin et al. (2012) double-blind trial (described in Section 5.2) provides the most robust human data, showing reductions in BMI and body fat ratio at 12 weeks, though independent replication is still needed.

5.8 Antiviral Activity

An in vitro study showed that the ethanol extract and specific phlorotannin compounds from E. cava exert antiviral activity against the porcine epidemic diarrhea coronavirus (PEDV) by inhibiting viral hemagglutination binding to sialic acid (SA) receptors in the host cell. Compounds that act by inhibiting both viral entry and replication were described as particularly viable antiviral drug candidates.

Evidence strength: All antiviral evidence is in vitro only. No human clinical trials examining antiviral effects have been reported.

5.9 Anticancer Activity

Three structurally distinct phlorotannins (dieckol, 7-phloroeckol, and 8,8′-bieckol) from E. cava were investigated for their regulatory effects on inflammation-associated ovarian cancer progression. By integrating network pharmacology, molecular docking, and molecular dynamics simulations with in vitro validation in ovarian cancer cells and tumor-associated macrophages (TAMs), researchers aimed to delineate the dual modulatory actions on the IL-17RA/Act1 and ERK1/2 pathways. This combined computational–experimental approach provided mechanistic insights into how E. cava phlorotannins attenuate cancer cell invasiveness and remodel the immune microenvironment.

Evidence strength: Anticancer evidence is entirely in vitro and computational. No human or animal tumor model studies with E. cava extracts have demonstrated clinical cancer treatment or prevention in humans.

6. Body Systems and Health Areas of Association

• Central Nervous System: Sleep promotion (via GABA_A-BZD receptor modulation); neuroprotection against oxidative stress and amyloid-beta toxicity in animal models.
• Cardiovascular System: ACE inhibition; antihypertensive effects in animal models; lipid-modulating effects in human trials; vascular endothelial protection demonstrated preclinically.
• Metabolic / Endocrine System: Inhibition of α-glucosidase and α-amylase; reduction of postprandial blood glucose in human trials; antiobesity effects in preclinical and limited clinical research.
• Immune System / Inflammation: Downregulation of NF-κB, COX-2, iNOS, TNF-α, and IL-6 in preclinical models; reduction of leptin resistance and macrophage infiltration in obese animal models.
• Integumentary System (Skin): Tyrosinase inhibition and inhibition of melanin biosynthesis in cell studies.
• Gastrointestinal / Hepatic System: Hepatoprotective activity noted in preclinical literature; historical use for gastrointestinal ailments.
• Musculoskeletal / Exercise Physiology: Preliminary human evidence for extended time-to-exhaustion in endurance exercise.
• Thyroid: Source of iodine; relevant to thyroid health both positively (iodine sufficiency) and potentially negatively (excess iodine in susceptible individuals).

7. Dosage Forms and Dosages Reported in Studies

Ecklonia cava extracts are often dosed by polyphenol content. The following dosages are reported from specific studies and regulatory assessments:

• 72 mg and 144 mg ECP/day — used in the 12-week randomized, double-blind, placebo-controlled trial in 97 overweight Korean adults examining anthropometric and lipid parameters.
• 500 mg AG-dieckol three times per day (1,500 mg/day total) for 12 weeks — used in a randomized clinical trial in 73 participants with elevated fasting blood glucose.
• 500 mg/day for 7 days — used in a randomized, double-blind, placebo-controlled trial investigating phlorotannins for sleep disturbances in adults.
• 500 mg/day for 4 weeks — used in a study of 72 adults with sleep problems.
• 400 mg/day — used in an open-label study of 52 individuals with hypercholesterolaemia examining phlorotannins with a phlorotannin content of 98.5%.
• 600 mg as a single dose — used in a double-blind, crossover RCT of 20 prediabetic patients for investigation of acute postprandial blood glucose effects.
• EFSA maximum daily intake guidance: 163 mg/day for adolescents aged 12 to 14 years, 230 mg/day for adolescents above 14 years of age, and 263 mg/day for adults.
• Maximum reported dose in human studies: up to 1,500 mg daily for 12 weeks, showing no adverse effect on study subjects.

8. Safety Considerations and Interactions

Regulatory Safety Assessments

The safety of Ecklonia cava consumption in humans was assessed by the FDA in the USA and the European Food Safety Authority (EFSA), and both authorities granted safety approval as a new dietary ingredient for supplementation.

The EFSA conducted a formal scientific opinion. A subchronic repeated dose oral toxicity study in rodents was provided, which tested the novel food at daily doses of 0, 375, 750, and 1,500 mg/kg body weight (bw). The EFSA Panel considers the mid-dose, i.e., 750 mg/kg bw per day, as the NOAEL (no-observed-adverse-effect-level) of the study. Taking into account the NOAEL of 750 mg/kg bw per day and by applying an uncertainty factor of 200 (composed of 100 to account for inter- and intraspecies variability, plus a factor of 2 to extrapolate from subchronic to chronic exposure), the Panel considers an intake level of 3.75 mg/kg bw per day as safe.

Based on the genotoxicity tests provided, the Panel notes that there is no evidence of genotoxicity for the novel food. The risk of allergic reactions to the novel food is low.

Iodine Content and Thyroid Concerns

Given the high iodine content of the novel food, such content should be indicated on the label in order to warn the consumer not to use the novel food together with other food supplements and/or drugs high in iodine. In the upper range of iodine content as indicated in the specifications (up to 650 mg/kg), the proposed intake of the novel food (360 mg) would lead to an iodine intake of 234 μg. In addition to iodine intake from food (excluding other food supplements), the total intake might exceed the reference value for iodine but will not exceed the upper level (UL: 450 μg for adolescents from 11 to 14 years, 500 μg for adolescents from 15 to 17 years, and 600 μg for adults).

Thyroid problems are a noted concern because Ecklonia cava contains iodine, and iodine might make thyroid problems worse. Taking Ecklonia cava along with amiodarone (which also contains iodine) might increase the levels of iodine in the blood. Too much iodine in the blood can cause side effects that affect the thyroid. Taking Ecklonia cava along with medications for an overactive thyroid might change the effects of these medications. Iodine can increase or decrease thyroid function. Taking Ecklonia cava along with thyroid hormone medications might also change the effects of these medications.

Potential Drug Interactions and Flagged Concerns

The EFSA review noted that one member state suggested considering a potential effect of the novel food on glucose metabolism of diabetic individuals and people on anticoagulant therapy. One member state also mentioned putative sleep-inducing effects of phlorotannins, claimed to have characteristics of GABA_A-BZD receptor ligands.

Age Restrictions and Special Populations

The target population for the novel food as assessed by EFSA is healthy individuals over the age of 12 years, with no other restrictions of use. There is not enough reliable information to know if Ecklonia cava is safe for children under 12 years old.

Human Tolerability

Research studies show that the use of E. cava as a daily food supplement is safe for humans over 12 years of age, and there are no side effects reported on animal health. The maximum reported dose in human studies was up to 1,500 mg taken daily for 12 weeks, showing no adverse effect on study subjects.

Overall Evidence Characterization

Scientific studies are still preliminary. As much of the available research was conducted in test tubes and animals, the findings may not apply to humans. Previous in vivo studies have missed important factors like hormones, obesity-related biomarkers, and important liver biomarkers, which are related to obesity. There is a lack of well-performed studies related to E. cava efficacy for high-fat diet-induced obesity. While the regulatory approvals from both the FDA (as a new dietary ingredient) and EFSA (as a novel food with defined maximum intakes) establish a safety framework, the clinical efficacy evidence base across most health areas remains at an early stage, primarily derived from small-scale trials, often conducted by research groups with product affiliations, and requiring independent replication.

References

• Shin HC et al. Effects of 12-week oral supplementation of Ecklonia cava polyphenols on anthropometric and blood lipid parameters in overweight Korean individuals: a double-blind randomized clinical trial. Phytother Res. 2012;26(3):363-8. PubMed PMID: 21717516
• Pyrogallol-Phloroglucinol-6,6'-Bieckol from Ecklonia cava Improved Blood Circulation in Diet-Induced Obese and Diet-Induced Hypertension Mouse Models. PubMed PMID: 31071969
• Influence of Supplementation of Ecklonia cava Polyphenols on Learning, Memory, and Brain Fatty Acid Composition in Mice. PubMed PMID: 37594112
• Anti-Obesity Effects of Ecklonia cava Extract in High-Fat Diet-Induced Obese Rats. PMC8868354
• Recent advances in pharmacological research on Ecklonia species: a review. PMC7090987
• The Phlorotannin-Rich Fraction of Ecklonia cava Extract Attenuated the Expressions of the Markers Related with Inflammation and Leptin Resistance in Adipose Tissue. PubMed PMID: 32215011
• Ecklonia cava Ameliorates Cognitive Impairment on Amyloid β-Induced Neurotoxicity by Modulating Oxidative Stress and Synaptic Function in ICR Mice. PMC11352165
• Effect of phlorotannins isolated from Ecklonia cava on angiotensin I-converting enzyme (ACE) inhibitory activity. PMC3085808
• Slow-Binding Inhibition of Tyrosinase by Ecklonia cava Phlorotannins. PMC6627058
• Inhibitory activity of minor phlorotannins from Ecklonia cava on α-glucosidase. ScienceDirect
• In vitro antiviral activity of phlorotannins isolated from Ecklonia cava against porcine epidemic diarrhea coronavirus infection and hemagglutination. PMC7127107
• Phlorotannins of the edible brown seaweed Ecklonia cava Kjellman induce sleep via positive allosteric modulation of gamma-aminobutyric acid type A-benzodiazepine receptor. PubMed PMID: 29243592
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• Protocol for a randomized controlled trial evaluating the effect of Hibiscus syriacus L. flower extract on sleep quality (citing Ecklonia cava KFDA health claim). PMC10157466
• Effect of seaweed (Ecklonia cava extract) on blood glucose and insulin level on prediabetic patients: A double-blind randomized controlled trial. PMC9922105
• Ecklonia cava Inhibits Glucose Absorption and Stimulates Insulin Secretion in Streptozotocin-Induced Diabetic Mice. PMC3356976
• Neuroprotective Effects of Ecklonia cava in a Chronic Neuroinflammatory Disease Model. PMC10142528
• Effects of Ecklonia cava Extract on Neuronal Damage and Apoptosis in PC-12 Cells against Oxidative Stress. PMC9705912
• Ecklonia cava Attenuates PM2.5-Induced Cognitive Decline through Mitochondrial Activation and Anti-Inflammatory Effect. PMC7997322
• Mixture of Phlorotannin and Fucoidan from Ecklonia cava Prevents the Aβ-Induced Cognitive Decline with Mitochondrial and Cholinergic Activation. PMC8400198
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• Ecklonia cava — Wikipedia (historical and taxonomic data)
• WebMD Natural Medicines monograph: Ecklonia cava — Uses, Side Effects, Precautions, Interactions, Dosing
• Phlorotannins from Ecklonia cava Regulate Dual Signaling Pathways, IL-17RA/Act1 and ERK1/2, to Suppress Ovarian Cancer Progression and Tumor-Associated Macrophage Activation. Marine Drugs 2026;24(1):12
• ScienceDirect Topics — Ecklonia cava overview (Polyphenols: Mechanisms of Action, 2018)
• Oh JK et al. Effect of Supplementation With Ecklonia cava Polyphenol on Endurance Performance of College Students. Int J Sport Nutr Exerc Metab. 2010;20(1):72-9. ResearchGate