Bladderwrack (Fucus vesiculosus) is a form of kelp that has been used medicinally for centuries. The main use of the herb has been for stimulation of the thyroid gland as a treatment for obesity and cellulite. Its high iodine content stimulates thyroid function and boosts metabolism. It has shown efficacy in the relief of rheumatism and rheumatoid arthritis and can be used both internally and as an external application for inflamed joints. It promotes healthy hair, skin and nails; it helps to balance the effects of stress; guards against sickness; aids digestion and respiration and generally promotes a healthy, balanced system. Bladderwrack is rich in iodine, calcium, magnesium, potassium, sodium, sulfur, silicon and iron and high in some B-complex vitamins. It contains moderate amounts of phosphorus, selenium, manganese and zinc and small amounts of Vitamins A, C, E and G. It also contains anti-sterility Vitamin S as well as Vitamin K. It is rich in algin and mannitol, carotene and zeaxantin with traces of bromine.