Ecklonia cava

BotanicalSeaweedBest with a meal

What is it

Ecklonia cava is a brown edible seaweed native to East Asian waters. Its extracts are rich in phlorotannins, a class of marine polyphenols studied for antioxidant and circulatory effects.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Antioxidant / cardiovascular markers

Limited Evidence

Small trials of Ecklonia cava extract suggest improvements in lipid markers and endothelial function, but evidence is limited and largely from industry-supported studies.

How it works

Phlorotannins such as dieckol and eckol have demonstrated antioxidant, anti-inflammatory, and mild vasodilatory activity in vitro and in animals. Some small human studies suggest effects on blood lipids, blood flow, and exercise performance, although high-quality trials are limited. Like other seaweeds, ecklonia naturally contains iodine, which contributes to its physiological effects and must be considered for thyroid safety.

Dosage

There is no RDA. Branded extracts (e.g., 'Seanol') are commonly used at 200-600 mg/day. DSLD does not provide a median dose for this entry.

When and how to take it

Take with food to reduce GI upset and standardize absorption. No specific time of day required.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Ecklonia cava frond/stipe extract

Most clinical work uses standardized extracts rather than whole seaweed.

Standardized for phlorotannin content in branded extracts.

Safety

Generally well tolerated in short-term trials at standardized extract doses. The iodine content of seaweeds can be problematic at high or chronic intakes.

Who should be cautious

Caution in thyroid disease (Hashimoto's, hyperthyroidism), pregnancy, breastfeeding, and bleeding disorders. Discuss with a clinician if on thyroid hormone or blood thinners.

Interactions

Possible additive effects with antihypertensive, antiplatelet, and anticoagulant drugs. Iodine content can affect thyroid medication needs.

Food sources

Ecklonia/seaweed (edible)

Amount
varies
%DV
—

Frequently asked questions

Will ecklonia cava lower my blood pressure?⌄

Some studies suggest mild effects on vascular function. It is not a substitute for prescribed antihypertensive treatment.

Does it contain iodine?⌄

Yes. Like other seaweeds, ecklonia contains iodine, which is important to consider for thyroid health.

References

Ecklonia cava on Wikidata — Wikidata link

Ecklonia cava on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Ecklonia cava (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.