Laminaria is a brown seaweed, commonly called kombu or kelp. It supplies a lot of iodine, a mineral your body needs to make thyroid hormones.
People use it mainly as a dietary source of iodine. The fiber in the seaweed also helps with bowel regularity. Others take it for basic nutrient support.
You can buy the dried whole leaf, a powder, or capsules. Iodine levels swing wildly between products, from roughly 50 to over 500 micrograms per serving, so always read the label.
Too much iodine can throw your thyroid off balance. Laminaria can pick up heavy metals like arsenic, so stick with brands that test for contaminants. Anyone with a thyroid condition should talk to a doctor before taking it.