A Microdose of Lithium in the Water Could Reduce Military Suicides

4566450 (1)

While the health news of the year will be focused on the SARS-CoV-2 virus, suicide remains on track to be the second-leading cause of military deaths, the same as it has been for the past 14 years. The Secretary of Defense, Dr. Mark Esper, says he has no answer for the record levels of military suicides that were recently highlighted when the USS George H.W. Bush suffered a string of three suicides in five days. And he’s not the first to struggle with this issue. Successive heads of the Department of Defense have seen suicide rates increase on their watches.

While Esper struggles with this complex issue, help may come by way of new science. Our answer is something that can be done quickly, cheaply, and non-invasively. It won’t involve more annual training, special programs, or hotlines. It just requires that we acknowledge that our current programs aren’t working, and it requires considering a scientific proposal that has been widely discussed for over twenty years.



Certain regions in the United States, Japan, Austria, and Greece have significantly lower rates of suicide than their neighbors, and many scientists believe it’s something in the water. Specifically, there are higher-than-normal levels of lithium, and a large body of scientific research has suggested that where lithium exists naturally and thus manifests in the drinking water, violent crimes and suicides are statistically far less frequent.

Whenever a suicide occurs, there is a natural human tendency to look for a simple reason or solution. We may point to trauma, substance abuse, medications, mental illness, or even status as a veteran. However, most people with trauma, substance abuse, medication use, mental illness, and veteran status do not die by suicide. There is a complex interweaving of personal, biological, and social factors that all influence the risk of suicide. The proposal we are suggesting is not sufficient, on its own, to prevent all suicides. There are still systemic issues to be addressed: timely access to good health care, structural supports, and — particularly in the military — operational stress.  However, reducing the risk for some people is precisely how evidence-based suicide risk reduction works. Microdose lithium may influence suicide risk such that a smaller proportion of people die, in the same way that known risk factors (like bullying) increases the proportion of those who die by suicide.

Why Lithium?

Lithium has long been known to have mental health benefits; it has been used as a treatment for mood disorders since the 1800s. A 1990 study examining 27 Texas counties with varying levels of lithium in their water supplies found that a reduction in violent crimes and suicide were strongly correlated to lithium levels. The counties where lithium levels were the highest had nearly 40 percent fewer suicides than those where it was the lowest. Similar studies around the world, including Japan, Greece, and Austria reinforced the finding that higher levels of lithium salts in water reduced suicide rates. As the Austrian study noted, “there is increasing evidence from three independent countries and continents that lithium in drinking water is associated with reduced mortality from suicide.” That said, there are three other studies (from Italy, England, and Denmark) whose results bear mentioning. The Italian study reported “an uncertain” association between lithium levels and suicide rates, and the Danish study stated that “there does not seem to be a protective effect of exposure to lithium on the incidence of suicide with levels below 31 µg/L in drinking water.” Finally, the English study found no link between lithium levels below 21 µg/L and suicide rates.

What to make of this? The studies that highlighted the most significant reduction in suicide rates also looked at cases where the maximum concentrations of lithium were much higher than the English and Danish studies; the Greek study included lithium concentrations of up to 121 µg/L, and the original 1990 study in Texas included levels as high as 219 µg/L. The most recent study — from Lithuania in 2019 — found that “the effect of lithium intake with drinking water associated with a lower incidence of suicide in a nonlinear way; an anti-suicidal effect of lithium in drinking water is not present if a lithium concentration is below a certain level.” That level, according to this study, is approximately 30 µg/L, which correlates well with the findings from the English, Danish and Italian studies. Finally, a 2020 meta-analysis of 14 studies of the relationship between lithium and suicide found “the odds of suicide decreased by increasing lithium concentration in drinking water,” and closed with the authors stating that “we are in a dire need of well-designed clinical trials to confirm the protective effect of lithium against suicide death.”

As a medical professional and a military leader, we couldn’t agree more. A preponderance of the studies already conducted show a significant link between lithium levels over 30 µg/L and a reduction in suicides in particular and, in some studies, violent and criminal behaviors overall. So, having made the case for why we should study microdose levels of lithium as a suicide prevention measure, let’s talk about how this prophylaxis could be quickly and cheaply deployed by the U.S. military to evaluate its effectiveness at reducing suicide rates. Nimitz-class aircraft carriers like the USS George H.W. Bush are self-contained, floating cities, home to over 6,000 sailors. At sea for months at a time, they represent both a military community in need of additional suicide prevention support, and an ideal environment for piloting the use of microdose lithium as a suicide prophylaxis.

How to Study the Question in the Navy

In the 18-month period between May 2012 and October 2013, a study by Navy doctors across seven aircraft carriers found 425 incidences of sailors who “experienced suicidal ideation with or without intent, suicidal preparatory behaviors and attempts with or without harm, non-suicidal self-directed violence, or completed suicide.” The study also noted, “Occupational stress while the ship was at sea (as opposed to while in port) was three times as likely to be named as the trigger” for a suicidal event, and that “Only patients who self-reported suicidal ideation or who attempted or completed suicide or another form of self-harm were included. It is very likely there are many more personnel on board who experience suicidal ideation or another form of SDV (self-directed violence), but never seek help.” It’s worth noting that of those 425 incidences, 48 were attempted suicides, and four were completed suicides, half of which occurred at sea.

Clearly, this is a population who needs all the help it can get and introducing microdose levels of lithium into the ship’s water supply is a simple way to make sure they get more of it. Carriers generate their own potable water through distillation and can create about 400,000 gallons per day. That water is treated in accordance with the Manual of Naval Preventive Medicine, NAVMED P-5010-6, and a part of that treatment is the addition of 0.7 parts per million of bromine as an antibacterial agent, which equates to 700 µg/L. It would not be difficult to add a controlled low-ground water simulation (10th percentile in the US, or 5 µg/L) and a controlled high-groundwater simulation (90th percentile in the US, 500 µg/L) amount of lithium to the water during the treatment process. Water-soluble lithium is readily available in the form of lithium carbonate and lithium orotate; the amount needed to treat a carrier’s drinking water would cost about a penny per sailor per day. To run the sort of study we’re proposing, where half of all ships added 5 µg/L of lithium to their water treatment regime and the other half added 500 µg/L of lithium would be both cheap and easy; there are already instructions for treating shipboard water with powdered chemicals, as is often done for the purposes of chlorination.

Conducting the Study Ethically

Are we talking about a dangerous or concerning amount of lithium? In short, no. A recent United States Geological Survey found that levels of lithium present in American drinking water ranged from 7.6 µg/L to 580 µg/L, so the range of lithium already present in the environment is quite wide, yet pales in comparison to any medical dose of lithium carbonate. The highest sample collected in the U. S. drinking supply, 580 µg/L, translates to 0.58mg/L, or 1/150th of a starting dose of lithium for bipolar disorder. Lithium is used at high doses (600-1800 mg/day) to treat bipolar disorder and people may be concerned about the well-known phenomenon of “lithium toxicity” that can result from taking too much prescription lithium. But here it must be pointed out that at the levels of lithium required to reduce suicide risk (~100 µg/day) it would be impossible to drink enough lithium-fortified water to attain a toxic effect.

A large-scale clinical trial focused on military servicemembers may raise concerns about the ethics of conducting research on human subjects. Relevant to our proposal, the 2002 Defense Appropriations Act amended 10 USC 980 to allow for “an exceptional waiver by the Secretary of Defense of the advance informed consent process if a research project would 1) directly benefit subjects, 2) advance the development of a medical product necessary to the military, and 3) be carried out under all laws and regulations.”

Significantly reducing the number-two cause of military deaths through the use of a safe, unregulated mineral at doses found throughout drinking water in the United States certainly seems like it would be a prime candidate for such a waiver.

Additionally, when an issue is uncertain, the ethics for a randomized control trial come into effect. We do not do randomized control trials for things of which we are certain (for example, we would never propose a trial of parachutes versus no parachutes for skydiving), or for things that are implausible (we generally don’t do a trial of amethyst crystal energy for healing cancer either). The World Medical Association’s Declaration of Helsinki established three situations in which a randomized control trial to test a placebo intervention would be ethical (Table 1.)

So current principles of medical ethics would allow for a randomized control trial in which some ships had the lowest level of lithium treatment in their drinking water and others had the highest levels.

Lemon Juice; Fluoride; Lithium

And historically, the naval forces have a long tradition of adding key chemicals to the daily dietary intakes of their sailors. One of the first controlled clinical experiments in the history of medicine occurred in 1747 when James Lind, the naval surgeon aboard the HMS Salisbury, determined that oranges and lemons “were the most effectual remedies” for scurvy, which throughout the 18th century resulted in the deaths of more British sailors than combat. Unfortunately, medical theories of the day were no clearer on the cause of scurvy than the modern military is on the cause of suicides, so Lind’s findings were ignored for almost 50 years — much as the findings on low-dose lithium are currently being overlooked. It was not until 1794 that Lind’s research was confirmed through a four-month voyage where the addition of lemon juice to the crew’s diet resulted in zero cases of scurvy, and the entire British fleet quickly adopted the solution; which was, in chemical terms, the addition of ascorbic acid.

Also, this would not be the first time that a cheap and readily available chemical whose properties were discovered due to its natural occurrence in some water supplies would be considered for localized testing and then widespread implementation. We’re referring to fluoride, which has been shown to significantly reduce tooth decay. Originally the effect was noted because of high levels of fluoride that occurred naturally in the drinking water in Colorado. This resulted in several epidemiological studies published by the U.S. National Institutes of Health indicating that low levels of fluoride (between 1-8 mg per liter) prevented cavities. Those papers were followed by an experiment in 1945 with fluoridating the water in Grand Rapids, Michigan, a study whose results proved so promising that the United States quickly adopted the process as a standard for municipal water systems.

The parallels with lithium are startling. A natural substance is found in varying levels in the water supply with significant health benefits; numerous studies demonstrating that a few milligrams per liter of water contributes to the prevention of a dangerous condition; all that is lacking is a large-scale test of its efficacy. We stand with lithium today where we stood with fluoride in 1945. But instead of preventing cavities, we have a chance to prevent suicides.

There are other things the Department of Defense and American society can and should do to lower the risk of suicide. But of all the possible solutions to the tragic and complex problem of suicide, adding a low dose of lithium to the water is one of the simpler and easier to implement. If the Department of Defense is serious about reducing the suicide rate (and potentially reducing many other destructive behaviors at the same time) it is time to try something different from the standard approaches that have been failing us for the last decade and whose results are only getting worse, not better.

It’s time to roll out a pilot of microdose lithium delivered through the water for all hands and evaluate the results after the first year of implementation. If the suicide rate for naval vessels at sea is significantly decreased, the lithium prophylaxis should be implemented at all U.S. military bases that manage their own water supplies.

The alternative is to shrug and continue to tell the American people that there is no answer to our military suicide epidemic. But there could be.



Dr. Tyler Black, B.Sc., MD, FRCPC holds degrees from the University of Alberta (1999, 2003) and the University of British Columbia (2008). He is the medical director of one of North America’s only dedicated pediatric intensive psychiatric care units and a researcher specializing in suicidology. He has published numerous suicide-related research articles and is the developer of two instruments for the care of patients with psychiatric distress, the “ASARI” (www.asari.ca), a documentation tool to perform suicide risk assessment completely, and the “HEARTSMAP,” used in pediatric emergency departments to ascertain service need.

Lt. Col. Edward H. Carpenter, USMC is a graduate of the Air War College, holds degrees in mechanical engineering and national security affairs, and has served over 27 years in the Army and Marine Corps. He is currently serving in South Sudan with the United Nations, and his previous assignments include service as a CNO Strategic Studies Group fellow and as a squadron commander, where he lost one Marine to suicide. He has been published by the Marine Corps Gazette and won the Navy League’s Alfred Thayer Mahan award for his writing on force integration and military ethics.

Image: U.S. Air Force (Photo illustration by Staff Sgt. J.D. Strong II)

Correction: This article was revised to omit a quote from a private conversation that was not authorized for public reference. We apologize for this lapse in our standards.