Summary
The aim of this work is to determine if dietary patterns, specific foods, nutrients, or essential fatty acid plasma status are associated with an increased or decreased risk of self-harm behaviors amongst adolescents. We ask this question because i) the importance of nutrients and psychiatric function is being increasingly recognized and ii) if dietary patterns, specific foods, nutrients or essential fatty acid are identified as a significant risk factor, then these findings can potentially be translated to public health benefits. Finally, we do not propose that diet patterns, specific foods, nutrients or essential fatty acid are sole cause determinants of self-harm risk, but are to be evaluated as possible modifiable risk factors.

Risk Factors and Treatment of Self-Harm
Previous literature indicates that deliberate self-harm is often predicted by a stressful event, such as child abuse, early history of hospitalization or medical treatment, parental separation, etc. (Briere & Gil, 1998; Favazza & Rosenthal, 1993; Fliege et al., 2009). According to Greydanus et al.(2006), deliberate self-harm may occur in attempt to relieve “a terrible state of mind” in those engaged in such behavior. For example, self-cutting behavior often serves as a way to release unbearable pain from suppressed negative feelings driven by underlying depression and anxiety from conflicts with family and/or peers (Greyandus et al., 2006; Nixon & Jansson, 2002). Furthermore, repeated studies have found depression, history of sexual abuse, exposure to self-harm, and concerns about sexual orientation to be main predictors of repeating deliberate self-harm acts (Nixon & Jansson, 2002; Goldman-Mellor et al., 2014). Despite increased awareness and knowledge regarding the importance of deliberate self-harm, there remains a lack of consensus over how it should be assessed and treated.

Diet, Dietary Patterns and Mental Health Outcomes
Nutritional quality and dietary patterns are becoming increasingly recognized as important factors in the prevalence and incidence and treatment of mental disorders (Sarris et al., 2015). Many epidemiological studies, including prospective studies, have shown associations between healthy dietary patterns and reduced prevalence and risk for depression (Lai et al., 2014; Psaltopoulou et al., 2013). In particular, a traditional whole-food diet, consisting of higher intakes of foods such as vegetables, fruits, seafood, whole grains, lean meat, nuts, and legumes, with avoidance of processed foods, is more likely to provide the nutrients that afford resiliency against the pathogenesis of mental disorders (Sarris et al., 2015). Studies have also reported a relationship between “unhealthy” dietary patterns and poorer mental health outcomes in children and adolescents (O’Neil et al., 2014). Poor diets consisting of high amounts of fat and sugar are associated with adverse mental health outcomes (O’Neil et al., 2014). Evidence is steadily growing for the select use of nutrient-based supplements as monotherapies or augmentation therapies to address mental health outcomes (Rucklidge et al., 2013). Multiple studies report that omega-3 fatty acid supplementation (in isolation, or in combination) is beneficial in the management of bipolar depression, post-traumatic stress disorder, and major depression; and is indicated in the prevention of psychosis (Mischoulon & Freeman, 2013, Hallahan et al 2016).

Here we propose to extend the examination of dietary patterns, specific foods, and specific nutrients to risk of self-harm and suicide risk factors. Only one study has reported associations between “prudent “Japanese dietary patterns (i.e., vegetables, mushrooms, fish, and seaweed) and lower risk of suicide mortality (OR 0.46, 95% CI 0.28–0.75, p<0.005) (Nanri et al., 2013). To our knowledge, no studies have examined relationships between dietary patterns specific foods and deliberate self-harm. Data from epidemiological studies have also indicated that low fish consumption may be a risk factor for suicide mortality. For example, one longitudinal study followed up 256,118 Japanese participants for 17 years; those who ate fish daily had a lower risk of death from suicide (OR 0.81; 95% CI 0.27–0.91) compared to participants eating fish less than daily (Hirayama, 1990; Karger, 1990). Another study in Northern Finland examined data from 1,767 participants and found that frequent fish consumption significantly reduced the risk of depressive symptoms (OR = 0.63; p < 0.03) and suicidal thinking (OR = 0.57; p < 0.04) after adjustment for confounding variables (Tanskanen et al., 2001). Blood compositional studies have reported that low omega-3 status is associated with greater risk of suicide death amongst US Military personnel (Lewis et al., 2011); in Belgian patients (De Vriese et al., 2004); and amongst Chinese subjects with suicide attempts (Huan et al, 2004). One randomized controlled trial of emergency room patients with deliberate self-harm found that 2 grams/day of omega-3 supplementation reduced suicidal thinking by 45%, depressive symptoms by 50%, perceived by 30%, and increased reports of happiness by 33% (Hallahan et al., 2007). Lastly, omega-3 fatty acid supplementation is currently being examined for US Military veterans at risk for suicide (Marriott et al., 2016).

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