(abstract from: Medical Hypotheses, Volume 72, Issue 5, Pages 501-503; K. Zachariassen, T. Flaten.)
"East African immigrants to Scandinavia are admitted to mental hospitals far more frequently than native Scandinavians. Most of these patients are admitted for psychosis, commonly ascribed to problems adapting to the new culture. However, psychosis is also known to be associated with hyperthyroidism, and the high frequency of psychosis among East Africans in Scandinavia may at least in part be due to hyperthyroidism rather than cultural problems. Large areas in East Africa are notorious for high natural concentrations of fluoride in water and plants. Fluoride inhibits the production of thyroid hormones. To maintain normal thyroxin levels the body increases the capacity for thyroxin production. Goitre is caused by such a compensatory mechanism, and endemic goitre is widespread in many high-fluoride areas, even where dietary access to iodine is adequate. When people from such areas arrive in a low-fluoride area, their elevated capacity to produce thyroid hormones may lead to hyperthyroidism and subsequently to psychosis."
I can say from personal experience, as one who was exposed to heavy amounts of sodium fluoride (the standard) throughout his life until 46 months ago, that leaving a F- rich environment, and attempting to remove it completely from the diet by eating 'naturally,' is a surefire way to undergo some interesting mental and physical changes over the course of a couple years. At least. Although far healthier than I've ever been before, I am now incredibly sensitive to the 'fluoride response' when I consume it via the city water, or via inorganic foods which have usually been sprayed by fluoride pesticides (which are the most common). I usually take kelp (for the iodine), calcium (to bond the F-), and iron pills with me whenever I travel. Some fluoride stil enters my diet through groundwater uptake into vegetables, grains, and fruits; and, by way of reconstitution into muscle mass from grazing foods by the animals and animal products I consume. Without those minimal sources, I'd probably have flipped my wig by now, too! I seriously despise the idea of being so biochemically attached to something just because it was a cofactor in my developmental stages -- it is thenceforth my body's expectations to consume it somewhat regularly -- and, that I must wait a total of 7 years to replace bodily cells for a true and complete acclimation to a regimen without it. Akin to quitting smoking (of which I've just hit my 8 year mark). I've been running 4, so far; 3 more to go, but I still haven't removed it completely from my diet. How can I?
And you know, I am not the only one who's had to undergo this genetic engineering experiment: