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Bdw2.5

Bladderwrack Research

Mostly mechanism / observationalLimited safety

4 peer-reviewed studies

What the evidence says

Mostly mechanism / observational

Most Bladderwrack studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.

Most evidence is from mixed-quality randomised trials published 1999–2019 with a typical study size of 65 participants.

Based on 4 studies · 1 RCT · 68 total participants

Confidence

Low

By outcome

Glucose & metabolicProposed glycemic/metabolic support from fucoidan and polyphenols (only shown in combination products, not bladderwrack alone) · Unknown
Too few graded studies1 study

Older research base

Newest study from 2019

199920092019

1RCTn=65 · small study2019

A nutraceutical combining Ascophyllum and Fucus polyphenols with chromium picolinate improved insulin sensitivity and glycemic status — but larger studies are required to confirm.

Derosa G, Cicero AFG, D'Angelo A, Maffioli P. · Phytother Res (2019)

Combination of Fucus + Ascophyllum polyphenols + chromium picolinate reduced HbA1c, fasting and postprandial glucose, and HOMA-IR vs placebo
Effect cannot be attributed to bladderwrack alone — it was a multi-ingredient product including chromium
Authors explicitly state larger randomized studies are needed

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2In Vitro1999

Regular consumption of algae, especially Laminaria species, could result in iodine levels sufficient to cause thyroid problems; Fucus was among the seaweeds analyzed.

Phaneuf D, Côté I, Dumas P, Ferron LA, LeBlanc A. · Environ Res (1999)

Analyzed Fucus vesiculosus and other seaweeds for metals (including arsenic, cadmium, lead) and iodine
Iodine-thyroid risk was flagged primarily for high-iodine Laminaria species; Fucus vesiculosus was among the seaweeds analyzed for contaminants
Recommends choosing low-iodine species for frequent consumption

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3Animal2011

Fucoidan from Fucus showed antithrombin and anti-factor Xa activity, with both antithrombotic and hemorrhagic (bleeding) activity increasing with dose.

Drozd NN, Miftakhova NT, Savchik EIu, et al. · Eksp Klin Farmakol (2011)

Fucoidan from a Fucus species had measurable antithrombin and anti-factor Xa activity
Both antithrombotic and hemorrhagic activity rose with dose in rats
Mechanistic basis for a plausible bleeding-risk interaction in humans

4Case Studyn=3 · very small study2004

These pilot data suggest dietary bladderwrack may prolong menstrual cycle length and exert anti-estrogenic effects, but well-controlled clinical trials are needed to confirm.

Skibola CF. · BMC Complement Altern Med (2004)

Only three pre-menopausal women — a case report, not a controlled trial
Associated with longer menstrual cycles and, in one woman, lower estradiol and higher progesterone
Hypothesis-generating only; author calls explicitly for controlled trials

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View in Research Library

Bladderwrack Research

Mostly mechanism / observational

Ascophyllum nodosum and Fucus vesiculosus on glycemic status and on endothelial damage markers in dysglicemic patients.

Evaluation of the contamination of marine algae (seaweed) from the St. Lawrence River and likely to be consumed by humans.

[Antithrombotic and hemorrhagic activities of fucoidan isolated from Fucus evanescens brown algae].

The effect of Fucus vesiculosus, an edible brown seaweed, upon menstrual cycle length and hormonal status in three pre-menopausal women: a case report.