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What is it? Overview Usage Side Effects and Warnings

Bladderwrack Side Effects and Warnings

Written by FoundHealth.

Safety Issues

Studies have found that levels of iodine vary widely among bladderwrack products. 1 Because of this, if you use bladderwrack as a regular supplement, there is a real risk you may receive an overdose of iodine and develop hyperthyroidism or hypothyroidism .

Bladderwrack and other seaweed preparations can also worsen acne and decrease iron absorption. 2 Finally, bladderwrack, like other sea plants, can concentrate toxic heavy metals, such as arsenic, from the surrounding sea water. 3 One report suggests that use of a bladderwrack product with a high heavy metal content is responsible for a case of kidney failure. 4 Heavy metals present particular risks for pregnant or nursing women, children, individuals with kidney disease, or anyone using bladderwrack in high doses or over a long period of time.


  1. Norman JA, Pickford CJ, Sanders TW, Waller M. Human intake of arsenic and iodine from seaweed-based food supplements and health foods available in the UK. Food Addit Contam. 5(1):103-9.
  2. Harrell BL, Rudolph AH. Kelp diet: a cause of acneiform eruption [letter]. Arch Dermatol. 1976;112:560.
  3. Walkiw O, Douglas DE. Health food supplements prepared from kelp—a source of elevated urinary arsenic [letter]. Can Med Assoc J. 1974;111:1301-1302.
  4. Conz PA, La Greca G, Benedetti P, Bevilacqua PA, Cima L. Fucus vesiculosus: a nephrotoxic alga? Nephrol Dial Transplant. 13(2):526-7.


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