Fish Oil for Depression and Mood: A Case for Omega-3 Fats

Last updated June 28, 2023.
Edited and medically reviewed by Patrick Alban, DC. Written by Deane Alban.

Fish oil adds omega-3 fats missing from the modern diet. Learn why it’s effective for depression and mood disorders and how to choose a quality supplement.

How the Omega-3s in Fish Oil Build Healthy Brain Cells

Omega-3 essential fatty acids (EFAs) are essential for good physical and mental health.

It’s no exaggeration to say that the quality of our brain cells depends on the availability of omega-3s.

Omega-3s are an integral structural component of brain cell membranes and nerve cells.

When omega-3 fats aren’t available, the brain will use whatever fats are available, thereby creating inferior brain cells.

" After only three weeks of omega-3 supplementation, 67% of study participants no longer met the criteria for depression.

This is very helpful for the brain.

Brain inflammation contributes to depression, anxiety, brain fog, ADHD, and even serious degenerative disorders like dementia and Alzheimer’s. 

In fact, brain inflammation, rather than an imbalance of brain chemicals, is now suspected to be a root cause of depression. 

Omega-6 fats, on the other hand, increase inflammation.

This is an excellent reason to minimize their consumption.

Unfortunately, typical modern diets — even if you buy your food at health food stores — are low in omega-3 and high in omega-6 fatty acids.

Until recently, the standard Western diet contained roughly equal amounts of omega-3s and omega-6s. 

This one-to-one ratio is considered ideal for health.

But now, the average person eats upwards of 15 times more inflammatory omega-6s than anti-inflammatory omega-3s. 

The best dietary source of omega-3s is wild-caught, cold water, oily fish such as: 

• salmon
• sardines
• herring
• halibut
• bluefin tuna
• mackerel

Wild-caught fish also contain fewer contaminants than farmed fish. 

Other healthy sources of omega-3s are wild game, grass-fed beef, pasture-fed pork and lamb, and free-range chicken and their eggs.

All of these contain significantly more omega-3s than their factory-farmed counterparts. 

The main dietary sources of inflammatory omega-6s are seed-based vegetable oils such as canola, safflower, and soybean.

These oils are not as healthy as we’ve been led to believe and are found in virtually all processed foods.

Some experts believe that the ratio of omega-6s to omega-3s is most important.

Others believe it’s the absolute amounts that matter most.

However you look at it, few of us get adequate omega-3s from food alone.

But you can easily meet your omega-3 needs with a fish oil supplement.

Check it out: Are you getting enough omega-3s in your diet? Or should you supplement? This short quiz will let you know for sure.
— Quiz courtesy of The Global Organization for EPA and DHA Omega-3s, a not-for-profit organization

Evidence-Based Benefits of Fish Oil for Depression, Mood, and Mental Health

More than 40,000 studies, including 4,000 human trials, have been published on the health benefits of fish oil. 

1. Fish Oil Works as a Natural Antidepressant

Fish oil has been found to improve depression symptoms in people of all ages and stages — pregnant women, children, teens, seniors, and everyone in between. 

A review of studies concluded that omega-3s have significant antidepressant properties. 

One clinical trial found that omega-3 supplements are effective, fast-acting antidepressants.

After only three weeks of omega-3 supplementation, 67% of study participants no longer met the criteria for depression. 

There are a few known mechanisms to explain how fish oil acts as a natural antidepressant.

Fish oil increases the volume of areas of the brain that control depression and mood. 

People who eat fatty fish at least once a week are 3 times more likely to respond to antidepressants than non-fish eaters. 

It’s believed that SSRI-resistant patients have abnormal fatty acid metabolisms.

Even when fish oil can’t take the place of an antidepressant, it’s shown to be a useful adjunct to prescription medications. 

3. Low DHA Level Linked to Suicide

An alarming increase in military suicides has researchers looking for answers.

Surprisingly, a low DHA level has been found to be a stronger predictor of suicide than battle-related stress.

Veterans with low levels of DHA were 62% more likely to commit suicide than those with higher levels. 

4. Fish Consumption and Seasonal Affective Disorder

The naturally occurring omega-3 oils in fish help winter blues and seasonal affective disorder (SAD).

Areas of the world where a lot of fish is consumed, like Japan and Iceland (103 and 186 pounds per year respectively), have low rates of SAD. 

This is particularly impressive when you consider Iceland’s northern latitude and corresponding lack of daylight during the winter.

Since most of us aren’t going to eat that much fish, fish oil supplements are a practical way to get the omega-3s that those with SAD need.  

5. Fish Oil for Postpartum Depression

Women who develop postpartum depression tend to be deficient in omega-3s.

Moms-to-be can use fish oil as a natural alternative to prescription drugs during pregnancy, and while breastfeeding, to help prevent postpartum depression.

An excellent side benefit is that the extra DHA, an essential component in breast milk, is also essential for the development of babies’ brains. 

6. Fish Oil for Anxiety

People with anxiety often have lower-than-normal blood levels of omega-3s. 

One study found that adults who took DHA and EPA experienced a reduction in symptoms of anger, anxiety, depression, fatigue, and mental confusion. 

Fish Oil Dosages for Depression

There is no clearly defined Recommended Daily Allowance (RDA) for the omega-3s in fish oil.

Experts generally recommend 500 to 1000 mg of total omega-3s per day to maintain health and avoid deficiency, with daily therapeutic doses of up to 3 grams generally considered safe. 

In one clinical trial, participants who took 800 mg of DHA, plus 1600 mg of EPA, experienced fewer symptoms of depression and related negative moods. 

How to Read a Fish Oil Label

It’s not always clear what to look for when buying fish oil and supplement labels can be confusing.

Here’s a typical fish oil supplement label.

First, you’ll see that there is 2200 mg of total fish oil and 2000 mg of total omega-3 fatty acids.

And, of that, 1400 mg is EPA and 480 mg is DHA.

A National Institutes of Health workshop that included a panel of worldwide omega-3 experts determined that you should consume a daily minimum of 220 mg each of DHA and EPA.

According to the label, this supplement exceeds those amounts. 

Note that fish oil’s antidepressant effects will not be immediate.

It can take anywhere from 4 to 12 weeks for the benefits to fully kick in. 

Other Tips for Taking Fish Oil Safely

Skip supplements that also contain omega-6s because you almost certainly get plenty of these in your diet.

Look for a statement on the label that the supplement is free of toxins and contaminants.

Since fish oil readily oxidizes, ideally find one that contains vitamin E or some other antioxidant to prevent spoilage.

There’s some debate as to whether cod liver oil is better than standard fish oil.

We suggest taking a pass on cod liver oil since it is high in vitamin A.

If you take enough cod liver oil to obtain therapeutic benefits for depression, you may wind up consuming an excessive amount of vitamin A.

Too much vitamin A can have serious consequences, causing nausea, dizziness, headaches, pressure on the brain, coma, and even death. 

Additionally, there’s evidence that vitamin A interferes with your body’s ability to use vitamin D, another nutrient critical for mental health and a positive mood. 

And obviously, if you have a known allergy to fish, you should not take a fish oil supplement.

Note: Talk to your doctor before taking fish oil if you take drugs that increase the risk of bleeding, like aspirin or blood thinners (such as warfarin). 

How to Maximize the Benefits of Fish Oil for Depression

One final tip for getting the maximum benefits from fish oil.

Take your fish oil and eat a healthy diet.

It’s unreasonable to expect fish oil alone to effectively treat your depression, especially if you continue to eat a diet high in inflammatory omega-6s.

Omega-6s in excess can negate the beneficial effects of omega-3s.

Research shows that taking fish oil and following a Mediterranean diet is significantly more effective at alleviating depression than doing either alone. 

The Mediterranean diet, one of the most popular and widely researched eating plans, emphasizes unprocessed foods such as vegetables, fruits, nuts, fish, poultry, eggs, olive oil, fermented dairy products, plus a moderate amount of red wine.