In search for a potential antidepressant that could be tested in clinical trials in which subjects are selected a priori based on inflammatory markers, the investigators turn to eicosapentaenoic (EPA), an omega-3 (n-3) fatty acid with anti-inflammatory properties. The ability of dietary n-3 fatty acids to mitigate the inflammatory response has been shown in human and animal studies. EPA and Docosahexaenoic acid (DHA) are the two major n-3 fatty acids found in oily fish and fish oil supplements, and both have shown anti-inflammatory properties. Supplementation of EPA and DHA in individuals with cardiovascular disease results in decreased plasma levels of CRP. N-3 fatty acids also have several other anti-inflammatory properties including i) Decreased chemotaxis of neutrophils and monocytes, ii) Decreased expression of adhesion molecules (e.g. ICAM & VCAM) on the surface of immune cells and in the circulation, iii) Decreased production of prostaglandins, iv) Increased synthesis of anti-inflammatory molecules such as resolvins and protectins, and v) Inhibition of T-cell proliferation. The mechanisms underlying these effects are not fully understood but likely involves n-3 fatty acids acting via cell surface and intracellular receptors controlling inflammatory cell signaling and gene expression patterns. In addition to the well-established anti-inflammatory effects of n-3 fatty acids, they may also have beneficial effects on oxidative stress and cell aging parameters such as leukocyte telomere length and telomerase activity. However, more research is needed in order to confirm these relationships, and therefore the investigators will, in addition to assessing inflammatory markers, also study the effects of n-3 fatty acids on markers of cellular aging and oxidative stress.