" Researchers, for instance, have measured the amount of naturally occurring lithium in tap water in twenty-seven counties in Texas and found a negative association between lithium levels in the water and suicide rates, meaning the higher the level of lithium in the water, the lower the suicide rate. Similar studies have been carried out elsewhere, such as in Japan, where researchers studied the tap water of eighteen municipalities of the Ōita Prefecture and noted that even very low levels of lithium in the water supply may be protective against suicide, and, by extension, against depression as well. Until 1948, the popular soft drink 7Up contained lithium citrate, a little boost contained in a can. "

― Lauren Slater , Blue Dreams: The Science and the Story of the Drugs that Changed Our Minds