What Are Omega-3 Fatty Acids?
Omega-3 fatty acids are one type of polyunsaturated fat molecule that we obtain from some of the foods we eat. Polyunsaturated fatty acids (or PUFAs) fall into the category of “good” fat molecules, which help the body remain healthy as opposed to saturated or trans fat, which can have a negative impact on your health. Omega-3 and other polyunsaturated fatty acids are important for the maintenance of good health and function in the brain, heart, and other bodily organs and processes. 
In terms of brain health specifically, there is a large body of research to support the theory that omega-3 essential fatty acids play a role in depression and other mental health treatment. For some patients, omega-3 fatty acids may act as a natural antidepressant and an alternative solution to pharmaceuticals for treating depression. 
Are Omega-3 Fatty Acids Important for Mental Health?
The brain — and central nervous system in general — contain a fairly high percentage of polyunsaturated fatty acids . Due to the high amounts of PUFAs in the nervous system, a sizable portion of research has aimed at determining the role that these molecules play in brain function. Through such studies, low levels of polyunsaturated fatty acids in the brain have been linked to a large number of mental illnesses including Alzheimer’s Disease, autism, anxiety, attention disorders, depression, and more [2, 3].
Even before looking into any specific biological brain research, there is cultural evidence and statistical data to show empirically and beyond a doubt that depression has increased significantly in the western world in the past century or so. There is also data to uphold that a healthier diet — perhaps one rich in good fats like Omega-3 — is increasingly less common across the board than more unhealthy diets full of sugars and saturated and trans fats (the bad fats).  While this data alone does not necessarily point to cause and effect with diet and depression, it has acted as the smoking gun that fueled a great deal of scientific research involving the connection between chronic depression or negative moods and what we are putting into our bodies.
How Are Omega-3s Linked to Depression?
Depression is elusive as it is simultaneously well known and yet still highly misunderstood. While most of us know what depression generally refers to, many do not fully understand how it is to live with it. Generally speaking, depression is a chronic mood disorder marked by negative cognitive symptoms such as fatigue, loss of interest in pleasurable activities, lack of enjoyment in life, guilt, and irritability--to name a few. 
Again, even before we look at any biological research, there is epidemiological evidence to support that groups of people whose diets generally consist of foods higher in Omega-3 content (like those with high fish consumption, for example) tend to have less depression overall [2, 4]. In looking at actual biological evidence, the correlation between depression and polyunsaturated fatty acid levels line up as well in favor of a diet higher in these good fats. Depressed patients studied showed that lower levels of these healthy fats in the blood and plasma indicated a higher likelihood of depression. 
Is It Better To Treat Depression Naturally?
As mentioned, numbers of depressed individuals are on the rise and increasingly more people are prescribed medications to combat this illness. However, questions and concerns arise around both the efficacy and safety of antidepressants, especially for long-term use often over the course of many years. Research to back these types of questions is sorely lacking.
Furthermore, with such a large number of different antidepressants available today, there isn’t a great deal of evidence to back any one pill in particular. As more drugs are being developed to treat depression, this problem only worsens. We continue to remain in the dark concerning major information points like which pills work better than others or whether or not certain antidepressants may be better at targeting particular symptoms of depression. 
Solid evidence supporting many antidepressants aside, individuals may be hesitant toward the notion of taking a psychotropic prescription drug long-term. As with other aspects of depression research, long-term effects of specific antidepressants are not particularly well known or understood . For this reason and many more, some individuals may choose to turn to alternative solutions for mental health upkeep and to find some of the best natural antidepressants.
So, How Can I Get More Omega-3 Into My Diet?
The best way to work more polyunsaturated fatty acid into your diet and up your levels of Omega-3 is by incorporating more seafood into your meals. Mackerel, herring, salmon, and trout include some of the highest levels, but most seafood is relatively high in PUFA content. Flaxseed and flaxseed oil are also high in good fat content. Both of these can be added to food in a variety of different ways to boost polyunsaturated fat content. 
If changing your diet slightly doesn’t appeal to you, Omega-3 is also available in capsule form.