Bladderwrack is a form of kelp that has been used medicinally for centuries. The main use of the herb has been for the stimulation of the thyroid gland as a treatment for obesity and cellulite. The high iodine content of the herb stimulates thyroid function which boosts metabolism. It has a reputation helping relieve the symptoms of rheumatism and rheumatoid arthritis and may be used both internally and as an external application for inflamed joints. Bladderwrack tea and bladderwrack powder are available to purchase.