It’s been interesting finding what is said about the basis for total iodine doses (inclusive of iodide) as large as this. For example, multiple “health-food” type sources claim that Japanese intake averages 13.8 mg/day.)
In comparison with almost any food almost anywhere in the world, that would be a nearly incredible amount of total iodine, not possibly consumed in the diet, or at least not on any remotely normal amount of calories.
It turns out though that the Japanese do have some very high iodine foods.
But it does not turn out that Japanese average total iodine dietary intake is anything like that value. Instead, measured values are 1 mg/day at the high end and often only about a third that value: Iodine content of various meals currently consumed by urban Japanese - PubMed
With regards to studies on safe upper limit to daily intake, there is little published. However the Chinese found hypothyroidism to begin developing at 0.8 mg/day: http://ajcn.nutrition.org/content/95/2/367.long
Iodine (I2) and iodide (I-) will not necessarily have the exact same effect: iodide is more chemically reactive. The product I bought is some undisclosed mixture of iodide and iodine. There is no way to tell whether what I have is mostly iodine, mostly iodide salt, or similar amounts of each.
My wife noticed a large increase in sweating. This might not have to be from increased metabolic rate. For example, while I have no evidence that it’s so, hypothetically it could be that this is a mechanism for getting rid of above-normal iodine levels. (Possibly well-above normal, as her dose has been 12.5 mg/day, and the total body content of iodine may normally be only about 20 mg total.)
Alin, as to how much water and salt to go with it, nothing extreme, whatever is reasonably comfortable, such as a glass of water and the amount of salt that might be with a salted meal and it might very well be taken along with that meal. But if taking no or almost no water and/or no salt, then with doses this high, until absorbed, the concentrations would be really high and the balance between the ions really abnormal.