Suicide deaths of active-duty US military and omega-3 fatty-acid status: a case-control comparison.

BACKGROUND The recent escalation of US military suicide deaths to record numbers has been a sentinel for impaired force efficacy and has accelerated the search for reversible risk factors. OBJECTIVE To determine whether deficiencies of neuroactive, highly unsaturated omega-3 essential fatty acids (n-3 HUFAs), in particular docosahexaenoic acid (DHA), are associated with increased risk of suicide death among a large random sample of active-duty US military. METHOD In this retrospective case-control study, serum fatty acids were quantified as a percentage of total fatty acids among US military suicide deaths (n = 800) and controls (n = 800) matched for age, date of collection of sera, sex, rank, and year of incident. Participants were active-duty US military personnel (2002-2008). For cases, age at death ranged from 17-59 years (mean = 27.3 years, SD = 7.3 years). Outcome measures included death by suicide, postdeployment health assessment questionnaire (Department of Defense Form 2796), and ICD-9 mental health diagnosis data. RESULTS Risk of suicide death was 14% higher per SD of lower DHA percentage (OR = 1.14; 95% CI, 1.02-1.27; P < .03) in adjusted logistic regressions. Among men, risk of suicide death was 62% greater with low serum DHA status (adjusted OR = 1.62; 95% CI, 1.12-2.34; P < .01, comparing DHA below 1.75% [n = 1,389] to DHA of 1.75% and above [n = 141]). Risk of suicide death was 52% greater in those who reported having seen wounded, dead, or killed coalition personnel (OR = 1.52; 95% CI, 1.11-2.09; P < .01). CONCLUSION This US military population had a very low and narrow range of n-3 HUFA status. Although these data suggest that low serum DHA may be a risk factor for suicide, well-designed intervention trials are needed to evaluate causality.