Omega 3 Fatty Acids, commonly called ‘fish oils’ are a category of fats that are essential to mental health. Essential, meaning that the body requires them for many important functions, and we cannot make them ourselves; we must get them from the diet.

Omega 3 fatty acids have been well studied for many conditions, and particularly for major depression and anxiety. The three main fatty acids used in research and supplementation are eicoapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linoleic acid (ALA). EPA and DHA are the 2 main active ingredients in fish oil that have been shown to effectively reduce depression, suicidality, and even some bipolar depression (Health Harvard)

Fish oils work for depression partly because they improve brain signaling by making neuron membranes more fluid. In the brain, fluidity means ease of communication. Without that, signals get lost, they stop working like they should, and we end up with low mood, dark thoughts, and low motivation. EPA and DHA also strongly reduce inflammation which is now thought to be one of the main causes of some types of depression.

With such strong evidence for their efficacy in fighting depression, they’re a commonly used supplement. But not all fish oils are created equal. Read on to learn about how to find the best fish oil supplement to help support mood and reduce inflammation.

Read the labels

If a supplement says “1g fish oil” on the front, this does not mean that there is actually 1g of active omega 3 fatty acids in the product. The oil may come from fish, but only the active ingredients EPA, DHA, and ALA “count” in a therapeutic sense. These compounds do the work, whereas other oils are fillers. Therefore, if a supplement claims it has “1g fish oil per capsule”, but only 300mg EPA and 200mg DHA, there is only a combined 500mg of effective omega 3 fatty acids per capsule. ALA is usually low or not listed in many fish oil products.

Triglyceride vs Ethyl Ester Forms

Once the fish oil is extracted from the source, it requires some processing before it can be bottled. It ends up in its first form, an ethyl-ester (EE) form. This is commonly found in supermarkets like Costco and in less expensive grocery-store products. If it is cleaned up and processed one step further, it reaches a triglyceride form. The EE form is cheaper, but it oxidizes and turns rancid faster than the triglyceride form. Learn about the form you’re taking and try to opt for the triglyceride form.

Look up the source of the fish oil

Not all sources are the same. The best omega 3s are from reliable, tested, cold water fish sources. The smaller the fish, the better, because small fish carry less toxic and heavy metal burden in general- but only some companies list the actual fish source. 3rd party testing is the most reliable.

Here are some locally-available fish oil companies that either use the EE form, list the sources, or test for impurities:

  • Genestra
  • NutraSea
  • Nordic Naturals

Here is some more info about purity testing for different brands.


Storage should be in a dark glass bottle to prevent sunlight from damaging the oils and from plastic leaching into it. Some companies have produced omega 3 products from plants, making vegan consumers very happy. Plant-based omega 3 comes from algae, and typically contain more ALA than omega 3s sourced from fish, which is thought to be particularly healthy for the heart.


This is important when choosing a fish oil. It is thought that EPA is more effective in treating depression than DHA, although the latter is still important to include. Researchers have suggested a ratio of 2:1 EPA:DHA in a fish oil. Some products actually have the ratio right on the front label to help you choose.

Conversely, research shows that EPA is more effective as an anti-inflammatory agent, whereas DHA is more effective at increasing membrane fluidity, both important qualities in a fish oil. Both are important, but studies show that EPA should be at least twice as high as DHA for depression. Some sources even recommend a 3:1 ratio of EPA:DHA if there is a tendency for more inflammation or more severe depression/anxiety.

If you’re curious if you can get omega 3 fatty acids from your diet, you’re definitely right! Eating 3 servings of fish a week is equivalent to taking 1g of fish oil a day. Since the recommended dose for depression is up to 4g/d, eating fish is a good start, and you certainly gain all the benefits of the protein and other nutrients, but you may need to supplement on top of that if you need a therapeutically higher dose.

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Dr. Christina Bjorndal, ND

Dr. Christina Bjorndal, ND

Dr. Christina Bjorndal, ND is considered an authority in the treatment of mental illnesses such as depression, anxiety, bipolar disorders and eating disorders using a physical, mental, emotional and spiritual approach. Having overcome many mental health challenges, Dr. Chris is a gifted speaker and writer and has shared her wellness philosophy with audiences from platforms such as the Jenny McCarthy show, the International Bipolar Foundation, and many health summits and docuseries. She is recognized as a top ND to follow by two independent organizations. Her book “Beyond the Label” is a comprehensive guide to naturopathic mental health.