Pure Powder Supports Healthy Thyroid Function* Excellent Source of Iodine Serving Scoop Enclosed Kelp is a large, leafy seaweed belonging to the brown algae family that grows in "forests" in the colder waters of the world's oceans. Kelp has been used for centuries as an important nutritious staple ingredient in Chinese, Japanese, and Korean cuisines. It is also an excellent source of iodine, which has been shown to be essential for healthy thyroid function.