Study Examines Association Between DHA Levels and Suicide Risk

WASHINGTON, DC — Diet impacts far more than waistlines and the risk of obesity.

In fact, the military has been paying close attention to not only the role of nutrition in maintaining physical health, but also how it relates to psychological health issues such as suicide and even TBI.

An IoM report released in April suggested that a high energy, high-protein diet received immediately after a severe TBI injury and through the first two weeks of treatment may benefit patients with these injuries. The findings were part of an IoM review of the potential role of nutrition in protecting against or treating the immediate and near-term effects of TBI. The report was done at the request of DoD, which asked the IoM to review the potential role that nutrition could play in providing resilience or treating TBI.

Now, in another recent study adding to the literature on nutrition, researchers found that low levels of highly unsaturated omega-3 essential fatty acids, in particular docosahexaenoic acid (DHA), may be associated with increased risk of suicide in servicemembers.

The retrospective study, conducted by researchers from the Uniformed Services University of the Health Sciences and the National Institute of Alcoholism and Alcohol Abuse in Bethesda, MD, sought to determine whether low levels of neuroactive, highly unsaturated omega-3 essential fatty acids (n-3 HUFAs), in particular DHA, were associated with increased risk of suicide death among active-duty U.S. military.

Suicide and Omega-3 fatty acids

For this study, researchers compared levels of omega-3 fatty acids of 800 troops who committed suicide with those of 800 randomly selected troops who were matched by age, sex and rank. While the researchers discovered that all of the troops had low omega-3 fatty acid levels, suicide risk was greatest among individuals with the lowest levels of DHA, the major omega-3 fatty acid concentrated in the brain.

“We were surprised at just how low the omega-3 [fatty acid] levels were in the blood of all 1,600 samples we checked,” said lead study author Army Col. Michael Lewis, MD, who conducted the study with the researchers while he was director of the Division of Epidemiology and Biostatistics, and assistant professor at the Uniformed Services University.

Lewis is currently at the Defense and Veterans Brain Injury Center (DVBIC), where he is the principal investigator for the congressionally-mandated Longitudinal Study on Traumatic Brain Injury in Iraq and Afghanistan veterans. In addition, he has been developing a research program focused on the use of nutritional therapy, omega-3 fatty acids, in particular, for the prevention and treatment of head and psychological trauma with the U.S. Army Military Research and Materiel Command, NIH and industry partners.

In the study when the population was stratified by levels, those with lower levels of omega-3s had a 62% increased risk for a documented suicide.

Still, Lewis said that, while the study shows a strong association between low omega-3 blood levels, in particular DHA, and active-duty military suicides, it does not prove causality. To understand if there is a true causal relationship, further research is needed, he said.

“Omega-3s are a potential tool for suicide prevention, not a cure,” he told U.S. Medicine. “Suicides are complex and multi-factoral.”

The study researchers concluded that evaluating “the efficacy of these levels of n-3 HUFAs in the primary prevention of suicide attempts, or as treatment following suicidal behaviors, merits consideration within the U.S. military.”

Low n-3 HUFA status is very likely due to a combination of several factors including “excess omega-6 linoleic-acid consumption and deficits in seafood consumption from the foods consumed at U.S. military dining facilities, available restaurants and choices made at home,” according to the study.

It is a diet deficiency that can be easily reversed, researchers said, suggesting ”low-cost dietary interventions that are likely to have multiple beneficial health effects. The American Psychiatric Association already recommends consumption of at least 1 gram per day of n-3 HUFAs for all patients with psychiatric disorders.”    

How nutrition impacts mental health

Joseph R. Hibbeln, M.D., acting chief, Section of Nutritional Neurosciences, NIAAA who was an author on the study, pointed out in a written statement that the findings of the study add to the research on the role of DHA and other omega-3 fatty acids in protecting against mental health problems and suicide risk.

“For example, a previous placebo-controlled trial demonstrated that 2 grams of omega-3 fatty acids per day reduced suicidal thinking by 45% as well as depression and anxiety scores among individuals with recurrent self-harm. In a prior study, we found that low blood levels of DHA correlated with hyperactivity of brain regions in a pattern that closely resembles the pathology of major depression and suicide risk,” he wrote.

The military has taken steps to better understand what constitutes an optimal diet for troops.

“Fitness cannot be separated completely from nutrition,” then chairman of the joint chiefs of staff Adm. Mike Mullen, wrote in the August 2010 Supplement to Military Medicine, which was devoted to Total Force Fitness.

That issue of Military Medicine cited nutrition as one of the eight domains of Total Force Fitness identified by a group of scientists, health, community and social leaders who met in 2009 to determine how to evaluate and measure what is necessary to keep troops resilient.

An article in that issue also suggested that Omega-3s seem to be related to suicide based on research, and that “achieving psychological fitness will require attention to nutrition.” Additionally, a conference sponsored by NIAAA, DARPA and the Samueli Institute in 2009, “Nutritional Armor for the Warfighter: Can Omega-3 Fatty Acids Enhance Stress Resilience, Wellness, and Military Performance” also looked at how the latest research on Omega-3 fatty acids may benefit troops.

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