Thyroid Support Iodine Source Mineral Supplement Great Source of Iodine Supports Healthy Thyroid Function May Support a Healthy Body Weight Science-Backed Quality Since 1969 Swanson Kelp is a unique formula that helps promote thyroid health. This ocean plant is packed with nutrients and is a rich source of iodine, an essential mineral known for healthy thyroid function. Each kelp tablet delivers 225 mcg of iodine.