The research showed that the drug appeared to lower the likelihood of death and suicide by over 60% compared with placebo.
The finding "reinforces lithium as an effective agent to reduce the risk of suicide in people with mood disorders," the scientists said.
Mood disorders are a major cause of global disability - the two main types are unipolar, which is commonly known as clinical depression, and bipolar disorder, which can also be called manic depression.
Both conditions are severe and long-term and involve extreme mood swings. Patients with bipolar disorder, however, also experience episodes of mania or hypomania.
People affected by a mood disorder have a 30 times higher likelihood of suicide than the general population. Mood stabilizing drugs, such as lithium, anticonvulsants or antipsychotics, used for the treatment of these conditions can help keep mood within normal limits.
However, experts have not known their role in suicide prevention, and therefore, researchers from the universities of Oxford, UK and Verona, Italy set out to examine whether lithium has a particular preventive effect for suicide and self harm in patients with unipolar and bipolar mood disorders.
Forty-eight randomized controlled trials consisting of 6,674 volunteers were examined. The studies compared lithium with either placebo or active drugs in long-term treatment for mood disorders.
Results showed that lithium was more successful than placebo in lowering the number of suicides and deaths from any cause.
However, no clear benefits were found for lithium in preventing deliberate self harm compared with placebo.
The experts said:
"When lithium was compared with each active individual treatment, a statistically significant difference was found only with carbamazepine for deliberate self harm. Overall, lithium tended to be generally better than the other active treatments, with small statistical variation between the results."
"This updated systematic review reinforces lithium as an effective agent to reduce the risk of suicide in people with mood disorders," explained the investigators.
The drug's anti-suicidal effects may be exerted by "reducing relapse of mood disorder," the authors said.
However, they pointed out "there is some evidence that lithium decreases aggression and possibly impulsivity, which might be another mechanism mediating the anti-suicidal effect."
Lithium has many side effects, the scientists pointed out. However, doctors "need to take a balanced view of the likely benefits and harm of lithium in the individual patient."
The authors concluded:
"Understanding the mechanism by which lithium acts to decrease suicidal behavior could lead to a better understanding of the neurobiology of suicide."
A 2009 study suggested that very low levels of lithium in drinking water may help prevent suicide in the general population.
Written by Sarah Glynn