The Mental Health Benefits of Fish Oil

Fish oil may ease symptoms of depression and support brain health

Woman holding fish oil supplement
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Fish oil might be helpful in the treatment and prevention of certain mental health conditions. This is because fish oil contains omega-3 fats, which may affect brain health and the functioning of certain neurotransmitters.

If you’re looking to get more omega-3s in your diet and you’re not a fan of eating fish, you might consider a fish oil supplement. According to the National Center for Health Statistics, over-the-counter (OTC) fish oil supplements are some of the most commonly used dietary supplements (glucosamine and chondroitin, often used for joint pain, are the others).

Fish oil sold over the counter contains EPA and DHA, the two types of omega-3s found in fish. Over-the-counter fish oil supplements are different than those prescribed for people with very high triglycerides, a type of fat associated with an increased risk of heart disease.

This article discusses the potential mental health benefits of fish oil. It also covers other health benefits, possible side effects, how much to take, and what to look for in fish oil supplements.

Mental Health Benefits

The omega-3 fatty acids found in fish are essential for brain health. They maintain the health of brain cells and help facilitate communication between cells. They are essential during the early development of the brain, but they continue to impact brain health throughout life. Older adults who are deficient in omega-3s show more advanced signs of brain aging, including smaller brain size.


Research has shown that fish oil may be useful in treating depression. Studies suggest that either a deficiency of omega-3 fatty acids or an imbalance in the ratio of omega-6 and omega-3 fatty acids in the brain may be linked to increased rates of depression. Further, a handful of small but well-designed studies support the use of fish oil as an addition to antidepressant therapy.

Premenstrual Syndrome

Premenstrual syndrome may have both physical and mental symptoms, such as changes in mood. A review of studies found that omega-3 fatty acids could effectively reduce the severity of PMS symptoms, including both somatic (physical) and psychological symptoms.

Other Mental Health Conditions

Although more research is needed to determine its effectiveness, fish oil has also been studied in the treatment of some other mental health conditions:

Research suggests that while omega-3 supplementation may be helpful for mild cognitive impairment, it does not appear to be beneficial in treating Alzheimer's disease. Fish oil supplementation also does not appear to improve the brain function of healthy adults.

Other Health Benefits

In addition to the potential mental health benefits of fish oil, research suggests that fish oil may be beneficial for other conditions.

Arthritis and Autoimmune Diseases

Fish oil has been found to be effective in the treatment of rheumatoid arthritis (RA) symptoms by reducing morning stiffness, joint tenderness, and the number of swollen joints and regulating the immune response. Fish oil can also help manage cardiovascular risk factors, which is important since people with RA are at an increased risk of a heart attack. 

According to the Arthritis Foundation, fish oil can also be used for knee osteoarthritis, lupus, psoriasis, and Raynaud's syndrome.

Heart Health

Although fish oil can’t prevent a heart attack or stroke, it can reduce some of the risk factors associated with both of these conditions, such as high triglycerides, high blood pressure, and atherosclerosis (hardening of the arteries).

If you take fish oil because you have high triglycerides, your doctor may prescribe a fish oil like Lovaza (omega-3 ethyl esters). Prescription fish oil capsules contain highly purified fish oil with a greater concentration of omega-3 fatty acids than most over-the-counter fish oil capsules. 


Fish oil may be helpful in both the prevention and treatment of depression. People with other health conditions, such as bipolar disorder or rheumatoid arthritis, may also benefit from fish oil.

Possible Side Effects

The side effects of fish oil most often occur when people take the supplement in high doses (more than 5 grams per day). In other words, the more you take, the more you're likely to experience side effects, which is why it's important to consult with a healthcare provider prior to taking a fish oil supplement.

The most common side effects include:

  • Nausea
  • Diarrhea
  • Heartburn
  • Abdominal pain
  • Belching a fish-like aftertaste ("fish burps")

High doses of omega-3 fats can slow blood clotting and increase your risk of bleeding or bruising if you are already taking an anticoagulant (blood thinner) like Coumadin (warfarin) or Plavix (clopidogrel). It can also reduce the body's ability to fend off infection.

According to the National Center for Complementary and Integrative Medicine, it’s not yet known whether people who are allergic to seafood can safely take fish oil.


Fish oil can have some side effects, although these tend to occur most often at high doses. Stomach upset and unpleasant tasting burps are perhaps the most common side effect. If your doctor has recommended taking fish oil for its mental health benefits, ask what you can do to help minimize these possible side effects.

Dosage and Preparation

Obtaining adequate amounts of the omega-3s fatty acids found in fish oil is essential for health. In addition to improving symptoms of some mental health conditions, these fatty acids are important for normal brain development and function throughout life. Deficiencies in omega-3s are linked to an increased risk for psychiatric disorders, including ADHD, bipolar disorder, dementia, depression, and schizophrenia.

How much fish oil you need will depend on your age, sex, and specific health condition, so it’s best to consult your healthcare provider before taking these supplements. Fish oil should be taken in whole capsules, with food and water, and not broken and sprinkled into food or liquids.

More research is needed to help determine the optimal dose for the prevention and treatment of different mental health conditions. However, one review suggested that consuming 0.6 grams of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish may lower the risk for depression.

The Food and Drug Administration recommends consuming no more than 5 grams (5,000mg) per day of EPA and DHA combined from dietary supplements. Higher doses are often used to lower triglycerides, but you should only take them under the guidance of a healthcare professional.

There is no established upper limit for omega-3's consumed from dietary sources (such as fish). However, research suggests that up to 10 grams (or 10,000 milligrams) of EPA and DHA is safe for most adults.

What to Look For

Although fish oil supplements are readily available at health food stores and pharmacies, it is important to speak to your doctor before taking them. When purchasing a fish oil supplement, the best way to tell if a product is reputable is to read the label.

Avoid any products that claim to "cure depression" or "reduce the risk of heart disease." While research suggests that fish oil has mental health and heart health benefits, more research is needed to determine the dosage, uses, and preparations that may be effective for those purposes.

According to the Food and Drug Administration (FDA), it's illegal "to market a dietary supplement product as a treatment or cure for a specific disease, or to alleviate the symptoms of a disease."

Look closely for added ingredients like fillers, binders, and flavorings. The fish oil supplement should also contain a seal of approval from a third-party testing organization to demonstrate purity levels.

These organizations include U.S. Pharmacopeia,, and NSF International. While this seal of approval does not guarantee that the fish oil is safe or that it will work, it does guarantee that there it doesn't have harmful levels of contaminants and that the product contains the ingredients listed on the label.

Another way to tell high-quality fish oil is by its smell and taste. Fish oil should not smell or taste "fishy." If it does, this indicates that the fish oil is starting to degrade and is becoming rancid. A strong smell may also be a sign that artificial flavors were added to the product.

Dietary Sources

The best dietary source of omega-3 fatty acids is fish, especially wild fish that eat a lot of omega-3-rich algae. Smaller cold-water fish, such as herring, mackerel, salmon, and sardines, are your best choices. Larger fish and farmed fish may accumulate toxins, such as mercury and dioxins, in their tissues. 

At this time, however, the benefits of consuming fish outweigh the risks for most people. The Dietary Guidelines published by the U.S. Department of Agriculture recommend that adults consume eight ounces of fish each week.

Other dietary sources of omega-3 fatty acids include:

  • Nuts and seeds (flaxseed, chia seeds, walnuts)
  • Plant oils (flaxseed oil, soybean oil, canola oil)
  • Fortified foods (eggs, milk, cereals, and orange juice)


If you want to consume fish oil for your mental health, supplements are an option, but you can also get the recommended daily amounts from dietary sources. Fish, nuts, seeds, plant oils, and fortified foods including cereal, eggs and orange juice are all great places to get dietary omega-3 fatty acids.

A Word From Verywell

Fish oil can have several health benefits, including protecting and improving mental health. Because the omega-3s found in fish oil are critical to brain health, evidence suggests that taking fish oil may protect brain function and even help treat mental health conditions such as depression.

This doesn't mean that taking fish oil is a substitute for medication or therapy. If you are experiencing symptoms of a mental health condition, talk to a healthcare provider. In addition to diagnosing your condition, they can provide further recommendations, including whether or not it might be helpful to take fish oil alongside other treatments.

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Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Nancy Schimelpfening
Nancy Schimelpfening, MS is the administrator for the non-profit depression support group Depression Sanctuary. Nancy has a lifetime of experience with depression, experiencing firsthand how devastating this illness can be.