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Bladderwrack is a species of seaweed known as Fucus vesiculosus that serves as a foodstuff and a source of Fucoxanthin, it is though to increase the metabolism via the thyroid but that is due to fixing iodine deficiencies historically.

Our evidence-based analysis on bladderwrack features 56 unique references to scientific papers.

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Summary of Bladderwrack

Primary information, health benefits, side effects, usage, and other important details

Bladderwrack (formal name Fucus Vesiculosis) is a brown seaweed which is a good source of iodine (the mineral needed for proper thyroid function) and of various L-fucose compounds.

Said L-fucose compounds can be seen as generally being anti-obesity, anti-inflammatory, anti-oxidant, and anti-carcinogenic. There are also some implications of them being anti-viral and anti-diabetic.

Benefits can be seen from ingesting brown seaweeds as foodstuffs, or by consuming the L-fucose compounds or the seaweed itself in supplemental form; although the latter should be taken alongside food.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

Although there is not a large amount of evidence currently, the evidence in humans has noted that 500mg of bladderwrack (basic extract of the seaweed, not concentrated) appears to be bioactive. This is a lower dose than the 4,000mg used in studies on Ascophyllum nodosum, and due to their similar composition the ideal range may be somewhere in between these two doses (or above 4,000mg).

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Human Effect Matrix

Unlocked for Examine Plus members

The Human Effect Matrix summarizes human studies to tell you what effects Bladderwrack has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine Plus members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-c Minor - See study
Appears somewhat potent at acutely reducing blood glucose following a meal (possibly by inhibiting absorption) but no long term studies.
grade-c Minor - See study
Appears to reduce insulin AUC after a carbohydrate containing meal
grade-c Minor - See study
Appears to be pretty effective at increasing insulin sensitivity acutely after a meal, which may be due to reduced insulin in serum.
grade-c Minor - See study
Limited evidence supports its efficacy, difficult to assess potency due to no reference drug.

Studies Excluded from Consideration

  • This study due to being highly confounded with other nutrients[1]

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Things to Note

Is a Form Of

Also Known As

Fucus Vesiculosis

  • Components of bladderwrack (fucoxanthine, fucoidins, and fucophlorethols) are fat/ethanol soluble in nature, and should be consumed via food (Seaweed) or with food.

  • Although the high fiber content of seaweed can theoretically inhibit uptake of lipophilic molecules (by excreting them in the feces via bile salts), the lipophilic components of seaweed appear to be taken up well in the gut when ingested via foods.

  • Bladderwrack is but one species of brown seaweed, and is the most notable due to being the first on the thyroid scence. Other species may have different or better effects.

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Click here to see all 56 references.