Bladderwrack plant, Kelp - Fucus Vesiculosus (Fucaceae)

Medicinal Use of Bladderwrack, Kelp – Fucus Vesiculosus (Fucaceae)


Brownish-green alga growing to 3 ft (1 m) in length. Has flat, usually forked, fronds containing air bladders.

Habitat & Cultivation

Bladderwrack is native to the North Atlantic shores and western Mediterranean, and is harvested all year.

Part Used

Whole plant.


Bladderwrack contains polyphenols, polysaccharides, and minerals, especially iodine (up to 0.1%). The polysaccharides are immunostimulant. The iodine may stimulate the thyroid gland.

History & Folklore

Bladderwrack has been employed as a fuel, as a winter feed for cattle, and as a source of iodine and potash.

Medicinal Actions & Uses

Due to its iodine content, bladderwrack is taken as an anti-goiter remedy. The plant appears to raise the metabolic rate by increasing hormone production by the thyroid gland, though this increase may be limited to poorly functioning thyroids. Bladderwrack is reputedly helpful in rheumatic conditions.


In one clinical trial (Italy 1976), patients taking bladderwrack lost much more weight than the control group. In more recent German research, the polyphenols and polysaccharides appeared to have antiviral and anti-HIV activity.


Do not take if pregnant or breastfeeding. If suffering from a thyroid illness or taking insulin, take only under professional advice.