Iodine in biology
The U.S. Food and Nutrition Board and Institute of Medicine recommended daily allowance of iodine ranges from 150 micrograms per day for adult humans to 290 micrograms per day for lactating mothers. However, the thyroid gland needs no more than 70 micrograms per day to synthesize the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of other body systems, including lactating breasts, gastric mucosa, salivary glands, oral mucosa, arterial walls, thymus, epidermis, choroid plexus and cerebrospinal fluid, among others.
Lugol's iodine
Lugol's is available in various strengths from 1% to slightly less than 13% iodine (wt/v). The most commonly-used 15% solution consists of 5% (wt/v) elemental iodine (I) and 10% (wt/v) potassium iodide (KI) mixed in distilled water, and has a total iodine content of 126.5 mg/mL. The iodide combines with elemental iodine to form a high concentration of potassium triiodide (KI) solution.