Yes, lithium is a naturally occurring element found in trace amounts within the human body. While most people associate it with a powerful psychiatric medication, the metal is an ultra-trace element absorbed from the environment and food supply. Scientific research is now dedicated to exploring the potential biological significance of this naturally occurring, low-level exposure, which is vastly different from the high doses used in medicine.
Lithium’s Natural Presence in the Human Body
Lithium is classified as an ultra-trace element, meaning it is present in extremely minute quantities within human tissues and fluids. The total amount of lithium in an average adult body is estimated to be only a few milligrams. Concentrations are typically measured in parts per billion (ppb) or parts per million (ppm) within various organs.
For instance, studies show that human blood contains lithium at a concentration of approximately 4 parts per billion, while the average for overall soft tissue is around 24 ppb. Bone tissue tends to accumulate higher levels, reaching concentrations of about 1.3 ppm. Lithium is not currently recognized as an essential nutrient by major health organizations, a designation reserved for elements like calcium or magnesium. However, its ubiquitous presence suggests a possible, yet still undefined, biological role in human health.
Dietary and Environmental Sources of Lithium
The primary way lithium enters the human body is through the consumption of food and, most notably, drinking water. Lithium is mobilized from rocks and soil by weathering processes, dissolving into groundwater and surface water. The concentration in drinking water varies dramatically based on local geology, leading to significant geographical differences in human intake.
In the United States, the average daily intake of elemental lithium is estimated to be between 0.65 and 3.1 milligrams. This intake is highly dependent on where a person lives; some regions have water supplies with barely detectable levels. Beyond water, the element is absorbed by plants, making grains and vegetables the main dietary sources. Cereal grains and vegetables contribute an estimated 66–90% of dietary lithium, with nuts, seeds, and root vegetables also containing measurable amounts.
Proposed Physiological Functions of Trace Lithium
The consistent presence of trace lithium has prompted research into its potential physiological functions, particularly concerning brain health. Epidemiological studies have observed a correlation between higher natural lithium levels in local drinking water and improved public mental health outcomes. For example, multiple studies across different countries have linked greater trace lithium exposure to statistically lower rates of suicide, aggression, and violent crime within a population.
These observational findings suggest that even at low, natural concentrations, the element may exert a neuroprotective effect. Researchers hypothesize that trace lithium may help regulate certain signaling pathways in the brain. It is thought to promote the up-regulation of neurotrophins, such as brain-derived neurotrophic factor (BDNF), which supports the growth, differentiation, and survival of nerve cells. Furthermore, trace lithium may help modulate inflammation in the central nervous system, a process increasingly implicated in various mood and cognitive disorders.
The Difference Between Trace and Therapeutic Lithium
The trace amounts of lithium found naturally are different from the doses used in pharmaceutical treatment. Therapeutic lithium, prescribed primarily for bipolar disorder, is given in milligram quantities, typically ranging from 600 to 1,200 milligrams per day. This pharmacologically active dose is up to a thousand times higher than the few milligrams consumed daily from food and water.
Therapeutic lithium requires careful and frequent medical monitoring because it has a narrow therapeutic index. This means the difference between an effective dose and a toxic dose is very small, necessitating regular blood tests to ensure serum levels remain within a safe, effective range. In contrast, the low levels found in nature are considered safe and do not require monitoring. The body efficiently processes and excretes them, meaning adverse effects like nephrotoxicity are not a concern at the microdose levels found in the natural environment.