Ecklonia Cava

Ecklonia cava extract · Seanol

Snapshot

Indications	Contraindications
Prediabetes glycemic control^{1, 2} Blood cholesterol^{3, 4} Body composition⁴ Sleep quality⁵ Respiratory symptoms⁶	Pregnancy or nursing⁷ Children under 12 years⁷

Ecklonia cava is an edible brown seaweed whose phlorotannin-rich extracts, including the SeaPolynol preparation, are sold as food supplements⁸. Phlorotannins act on gamma-aminobutyric acid (GABA) signaling, and the extract is taken mainly for sleep quality. It is also taken for postprandial glucose and cholesterol in adults with prediabetes, high cholesterol, or excess weight, and, combined with chrysanthemum extract, for respiratory symptoms.

Human research is limited to about seven small trials, mostly in prediabetes, blood lipids and weight, endurance exercise, hair loss, and respiratory health. Randomized trials in prediabetes found lower postprandial glucose with a dieckol-rich extract and after a single extract dose². A systematic review of marine algal polyphenols judged the evidence inadequate to confirm consistent effects on glucose and cholesterol⁹. A 2022 narrative review of animal and human studies describes sedative-hypnotic effects of phlorotannins, and Korea's Ministry of Food and Drug Safety has approved an extract as a health-functional ingredient for sleep quality⁵. Products listing Ecklonia cava are mostly capsules, with some powders; see Form comparison.

The European Food Safety Authority (EFSA) assessed phlorotannin use only in healthy individuals older than 12 years. Per product labeling, patients taking blood-thinning medication are directed to consult a physician before use⁷.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

30 sources, 18 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources