Natural Factors Fresh Kelp Extract is an effective way to meet the recommended daily requirements of iodine and essential trace minerals. It is made from fresh kelp that is sustainably harvested from the coastal waters of British Columbia and is rigorously tested for purity to ensure that it is free of contaminants and heavy metals. A precision extraction process is used to preserve the natural spectrum of minerals, vitamins, and iodine in fresh kelp. It is also fortified with potassium iodide to allow 800 mcg of iodine per drop, the most concentrated liquid iodine on the market.