Did you know…
Populations drinking water with higher natural trace levels of lithium have lower suicide rates. This has been documented in two independent large studies, in Texas in 1990 and in Japan in 2009, and confirmed by subsequent meta-analyses. Lithium is a nutrient before it is a medication. Its nutritional dose in mineral water and food is roughly 1,000-fold lower than the psychiatric dose used to treat bipolar disorder. The two doses do not sit on the same scale of risk.
The claim, in the reference of population psychiatry
Schrauzer and Shrestha (1990), using data for 27 Texas counties from 1978-1987, published in Biological Trace Element Research:
“The incidence rates of suicide, homicide, and rape are significantly higher in counties whose drinking water supplies contain little or no lithium than in counties with water lithium levels ranging from 70-170 μg/L. The differences remain statistically significant (p < 0.01) after corrections for population density.”
— Schrauzer & Shrestha, Biological Trace Element Research, 1990
Ohgami and colleagues (2009), in the British Journal of Psychiatry:
“Lithium levels [in tap water in the 18 municipalities of Oita prefecture] were significantly and negatively associated with SMR averages for 2002-2006.”
— Ohgami et al., British Journal of Psychiatry, 2009
A 2020 systematic review and meta-analysis in the Journal of Affective Disorders supported the pooled inverse association across multiple population studies.
The two doses are not the same drug
The psychiatric dose of lithium (for bipolar mood stabilization) is 600 to 1,200 mg per day of lithium carbonate, which delivers 100-200 mg of elemental lithium. The trace nutritional exposure in drinking water containing 100 μg/L, with 2 L of daily consumption, delivers 0.2 mg of elemental lithium: roughly a thousandth of the psychiatric dose. At the nutritional scale, the known toxicities of the psychiatric dose (renal, thyroid, tremor) do not apply. The physiological question is whether a population-level restoration of trace lithium to the food and water system, at the levels ancestral human populations were probably exposed to, would prevent measurable numbers of suicides.
What no jurisdiction has tested prospectively
No public-health authority has run a prospective trial of lithium water fortification for suicide prevention. The observational evidence has stood for thirty-five years. The intervention would be trivially cheap, technically simple, and reversible. The absence of the trial is not a scientific gap. It is an institutional one.
This entry is a companion to arguments on conditionally essential nutrients and to the broader framework on what a right to physiological maintenance would include.