Red Marine Algae & Hyperthyroidism

Fusus vesiculosus is a brown seaweed and is also known as bladderwrack or red algae, according to the National Institutes of Health (NIH). Red marine algae and other seaweeds are common components of Asian diets and are often used in dietary supplements. The high iodine content in red marine algae can lead to hypothyroidism or hyperthyroidism.

Iodine

• Sea water and the organisms that live in it are sources of iodine.

  Iodine is required for the body to produce thyroid hormones T3 and T4. These hormones are essential for protein synthesis, the conversion of compounds into usable glucose and the absorption of glucose in the intestinal wall, according to the International Program for Chemical Safety (IPCS).

Iodine and thyroid activity

• Supplements can trigger or worsen thyroid conditions.

  IPCS says that excess iodine can trigger or worsen hypothyroidism and hyperthyroidism, the under-production of thyroid hormones or their overproduction. IPCS says that people who have lived with iodine deficiency for many years are more likely to have thyroid reactions to iodine, females are more likely to be affected by excess iodine, and those with thyroid diseases may react strongly to added iodine in food, water or supplements.

Iodine and Hypothyroidism

• Seaweed harvest

  Hypothyroidism is often induced by excess iodine. Dietary or therapeutic iodine intake, as in the form of red marine algae, reduces the amount of circulating thyroid hormones, according to IPCS.

Bladderwrack and Thyroid

• Bladderwrack

  High iodine content in seaweeds may interfere with thyroid medications and alter thyroid function. Bladderwrack is thought to stimulate the thyroid and may have additive effects when used with other types of stimulants in supplements, according to the NIH.

Iodine Levels in Seaweeds

• Nori rolls

  A 2004 study published in the journal "Thyroid" measured the iodine content in popular dietary seaweeds. The researchers found that iodine levels were lowest in sun-bleached seaweeds and highest in young, freshly harvested seaweed. The researchers found it difficult to measure iodine contents because cooking and storage conditions altered iodine content, but they report that many Asian seaweed dishes may exceed the recommended upper intakes for iodine.