Fish oil supplements are a common complementary medicine used regularly by many Australians. They are a rich source of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are important nutrients for human health.

These fatty acids play a role in many everyday functions in the body including: changing cell membrane structure and function reducing inflammation regulating activity of the immune system, and reducing the likelihood of blood clots.

Fish oil supplements may be useful for people unable to gain adequate levels of omega-3 from their diet and they have demonstrated clinical benefit in the treatment of high blood triglyceride levels and rheumatoid arthritis.

Results from clinical trials have also suggested that omega-3 fatty acids may help ease symptoms of depression in some people.

However, the true magnitude of this benefit remains unclear as there are considerable differences between studies for important factors such as the omega-3 dose used, the length of time a dose was administered, the severity of the depression, and the presence of other co- existing mental and physical conditions.

In addition to variation in study methodology, the type of fatty acid may also impact the efficacy of omega-3 for managing depression, with supplements containing a higher ratio of EPA to DHA appearing to be more effective.

The omega-3 connection

The suggestion that fish oil (and thus omega-3 fatty acids) may be beneficial for treating depression first emerged following population-level studies reporting that diets high in oily fish were associated with lower rates of depression.

Since then it has also been shown that individuals diagnosed with depression have lower levels of omega-3 fatty acids compared with people who do not have depression.

Omega-3 fatty acids are an important component in the structure of nerve cell membranes, and can influence the way cells communicate with each other including the release and uptake of the neurotransmitters serotonin and dopamine.

Changes to serotonin and dopamine levels in the brain are thought to contribute to the development of depression in some individuals. Interestingly, it has also been shown that changes to brain tissue observed in animals with a dietary deficiency of omega-3 fatty acids are similar to those observed in patients with depression.

Is there a role for fish oil?

Based on current available data, fish oil supplements should not be considered as a replacement for other treatments of depression such as psychological (or talking) therapies or medicines (like antidepressants). There may be some benefits for people when fish oil supplements are used alongside more formal or established therapies for depression.

More studies are needed to better understand the place of fish oil supplements in the treatment of depression and other mental health conditions.

It’s important to remember that there’s no single treatment for depression that works for everybody. Talking to your doctor will help with finding the best approach for you.

Where can I find out more?

Feeling sad or in a low mood is something that we all experience from time to time. However if you or someone you care for are experiencing prolonged periods of sadness or low mood, or if these feelings are interfering with everyday activities, talk to your doctor about it.

If you have thoughts of suicide, seek help straight away. Lifeline offers 24 hour phone counselling on
13 11 14.

Last Reviewed: 05/10/2019

© Norman Swan Medical Communications.



References

NPS MedicineWise