Here we share scientific research on seaweed from Scotland - on the role seaweed can play in increasing iodine intake. Iodine levels in soil have been depleting as agriculture becomes more intensive, so seaweed, especially the brown ones, are a useful source of this important mineral. Note that too much is not good either. 5g dried kelp per day is a guideline, although this varies, as mineral levels in seaweed fluctuate through the seasons.

http://www.gla.ac.uk/about/avenue/issue57january2015/news/headline_378684_en.html