Is Suicide in US Military Personnel Related to Low DHA Status?
Suicide is a global problem, prevalent among adolescents, the elderly and active-duty military personnel. Among US active-duty military, suicide is the second leading cause of death, whereas in the general adult population, it ranks ninth. What attracted popular attention to this high occurrence was a news report that up until 2009, the number of suicides in the US military exceeded the number of combat deaths. This fact also drew the attention of researchers in the Uniformed Services University and the National Institutes of Health, Bethesda, USA. It is known that suicide is more likely among individuals with certain mental disorders, including depression, violent behavior and bipolar disorder. One feature common in these conditions is low concentrations of long-chain PUFAs or DHA, one of the two major long-chain omega-3s found in fish. A limited amount of evidence suggests that supplementation with long-chain omega-3s in individuals with a history of self-harm is associated with reduced suicidal thinking and depressive symptoms. A study in Japanese men and women who died by suicide found no association between high fish or long-chain omega-3 consumption and risk of suicide, except among women with very low fish intakes. These women faced a greater than three-fold risk of suicide. In this report, US researchers at the above-mentioned centers compared the blood levels of omega-3 PUFAs in a large number of active duty military personnel who took their own lives with an equal number of matched controls. The investigators were particularly interested in the concentrations of DHA, because of its function in neural transmission and membrane structure. The two groups did not differ in the concentrations of total or individual omega-3 PUFAs. However, when the concentrations of DHA were divided into eighths (octiles), those in the lowest octile compared with those in the highest were 75% more likely to die by suicide. If the observed DHA levels were separated into two groups above or below 1.75% DHA, those below this level were 62% more likely to die by suicide than those above 1.75%. The investigators also examined the mental health reports of all individuals who had been deployed and for whom complete reports were available. Several questions were more likely to have positive answers for individuals who subsequently took their lives compared with those who did not. These included feelings of detachment, avoiding situations, witnessing civilian or military deaths and discharging their weapons. These conditions and exposures contributed to a complex psychological environment where suicide risk was greater. The study is valuable in raising questions about the long-chain fatty acid status and nutrition of US military personnel. The study does not show causation, but provides grounds for considering DHA status as a possible suicide risk factor for military personnel who may face risky and disturbing environments. DHA status would be relatively simple to improve via diet or supplementation and could be evaluated. The study clearly documented the low long-chain omega-3 PUFA status in US military personnel, which may contribute to diminished mental health, undermine the ability to handle stress effectively and increase the risk of heart disease.