Linking omega-3 fatty acids and depression

Omega-3 polyunsaturated fatty acids (PUFAs) include α-linolenic acid (ALA), stearidonic acid (SDA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). The major dietary sources of omega-3 PUFAs are oily fish, vegetable oils (i.e., soybean, canola, walnut, flaxseed), and seeds (i.e., chia, hemp, flaxseed). Several epidemiological studies demonstrated a significant inverse association between dietary intake of fish and depression, which is one of the leading causes of disability worldwide. However, studies conducted on the association between dietary omega-3 PUFAs intake and depression reported contrasting results, suggesting that the preventive role of omega-3 PUFAs toward depression may depend on other factors correlated with omega-3 PUFAs intake, such as adherence to a healthier dietary pattern and lifestyle factors. Accordingly, clinical evidence proposed that supplementation with omega-3 PUFAs may improve the symptomology in depressed patients, although definitive statements on their use in depression therapy cannot be yet asserted. Several molecular mechanisms were hypothesized to be implicated in the protective role of omega-3 PUFAs, including regulation of neuro-inflammation, modulation of adult hippocampal neurogenesis, neurite outgrowth, and synaptogenesis. Even though, scientific evidence supports the neuroprotective effects of omega-3 PUFAs, there are still some controversies about their efficacy. Therefore, further research is needed in order to elucidate the role of omega-3 PUFAs toward both prevention and treatment of depression.