Depression is one of the top forms of mental illness. It is estimated to affect 10% of the American population, while women are twice as likely than men to develop it. The World Health Organization (WHO) suggests that by 2020, depression will be the second most common disease in the world after heart disease.
Clinical depression can be categorized in a variety of forms, including major depression, bipolar depression, and postpartum depression in new mothers. The diet is thought to play a major role in the prevention and treatment of all forms of depression.
The brain is rich in fatty acids and therefore requires a consistent intake of omega-3 fatty acids, which have a big impact on a person’s mood and emotions. Research demonstrates that an imbalance between omega-6 and omega-3 is associated with depression symptoms.
In this article, you will learn what studies say about omega-3 and depression, as well as the benefits of omega-3 for the various types of depression such as postpartum depression, major depression, childhood depression, and bipolar depression. We will also look at how much omega-3 is needed for treating depression, according to studies, and what foods rich in omega-3 could help stabilize your mood.
In this article:
Omega-3 and Depression: What Do Studies Say?
Research with clinical trials has long supported omega-3 fatty acids in the treatment of depression. For instance, a systematic review and meta-analysis of 31 observational studies with more than 20,000 cases of depression published in the Journal of Affective Disorders in 2016 supported the claim that dietary omega-3 is associated with a lower risk of depression.
How do omega-3 fatty acids reduce depression? Read on to learn how omega-3 impacts various parts of the brain, including the hippocampus, the hypothalamic-pituitary-adrenal (HPA) axis, the prefrontal cortex (PFC), and the striatum.
1. The Hippocampus
Some pre-clinical studies have suggested that omega-3 fatty acids act on the hippocampus to prevent or lower the incidence of depression. This includes a study published in the Journal of Nutrition in 2008 that found that rats fed a diet rich in a specific type of omega-3 called EPA (eicosapentaenoic acid) for six weeks had shown increased hippocampal concentrations of serotonin and dopamine, which suggests that omega-3 may prevent depression-like behaviors.
Other research published in the journal Lipids in Health and Disease in 2016 showed that a maternal deficiency of omega-3 impaired neurogenesis and reduced serotonin and norepinephrine levels in the hippocampus of neonatal rats.
Despite this evidence, in a study published in the Journal of Psychiatric Research in 2010, researchers did not find major changes in omega-3 levels in the post-mortem hippocampus of humans with diagnosed mood disorders. In this small study, the researchers suggested that hippocampal omega-6 rather than omega-3 is associated with depression.
2. The Hypothalamic-Pituitary-Adrenal (HPA) Axis
There is also research that explores omega-3 activity on the HPA (hypothalamic-pituitary-adrenal) axis. A study published in the Journal of Nutritional Biochemistry in 2013 found that maternal dietary omega-3 deficiency in rats was shown to provoke HPA hyperactivity with high cortisol levels while causing depression-like behavior in offspring.
This was supported in a 2013 study in humans that found a link between cortisol levels and blood concentrations of DHA (docosahexaenoic acid) and EPA in people with depression. In addition, other studies suggest that EPA supplementation will reduce HPA-axis activity and improve depressive symptoms in diagnosed depression patients.
3. The Prefrontal Cortex (PFC)
A study published in the Journal of Nutrition in 1994 found that a deficiency in omega-3 alters the membrane phospholipid composition of the prefrontal cortex (PFC) of the brain.
The researchers had observed reduced levels of omega-3 in the PFC of rats exposed to a diet deficient in an omega-3 fatty acid called ALA (alpha-linolenic acid). The omega-3 deficient rats also had lower levels of altered serotonin neurotransmission and endogenous dopamine in the PFC.
This suggests that these animals are more prone to depression.
Other research showed that a lifelong imbalance of omega-6 and omega-3 changed the fatty acid composition in the PFC, and then triggered depressive symptoms in mice.
In addition, omega-3 can also regulate PFC endocannabinoid signaling. This is likely because omega-3 deficiency can impair endocannabinoid synaptic transmission in the PFC, which may contribute to psychiatric disorders like depression. Having a lifelong omega-3 intake deficiency may also disrupt endocannabinoid neurotransmission in the PFC, reduce brain levels of DHA, and lead to depression symptoms.
4. The Striatum
The striatum is a subcortical region of the brain that is studied in depression due to its role in motivation and reward.
Long-term consumption of an omega-3 deficient diet can impair dopamine signaling and reduce brain-derived neurotrophic factor (BDNF) levels in the striatum of rodents. This suggests that omega-3 deficiency can Impact the striatum and increase the likelihood of depression.
That being said, other researchers failed to find differences in omega-3 levels in the post-mortem striatum of patients with most psychiatric disorders other than schizophrenia.
Benefits of Omega-3 for Depression
1. Postpartum Depression in Women
Postpartum depression affects about 10% to 20% of childbearing women. When left untreated, postpartum depression can lead to frequent depressive symptoms, which negatively impact the development of the infant. In severe cases, it can lead to maternal suicide or infanticide.
As a result, there is a critical need to prevent and treat postpartum depression while caring for the health of both mother and infant. A number of studies show that omega-3 deficiency may contribute to the development of postpartum depression.
One analysis published in the Journal of Affective Disorders in 2002 found that higher fish consumption was associated with lower incidence of postpartum depression. This led to a higher concentration of DHA in breast milk of the mothers.
At the same time, research also shows that DHA deficiency may play a key role in postpartum depression. Reduced brain DHA was associated with reduced hippocampal BDNF gene expression. Overall, a lower intake of fish and other omega-3 sources has been linked with depression during pregnancy.
Research published in the Journal of Nutrition in 2007 found that pregnancy and lactation deplete DHA from specific regions of the brains in female rats; therefore, DHA has the potential to prevent omega-3 deficiency in postpartum depression.
In rats fed low-ALA diets, the frontal cortex and temporal lobe regions of the brain were among the rats exhibiting the lowest levels of DHA.
In addition, women with more than one child or with pregnancies shorter than 24 months apart have been found to be at a higher risk of postpartum depression due to greater alterations in omega-3 fatty acids.
2. Omega-3 for Major Depression
There is also research that establishes a link between omega-3 fatty acids and major depression. Omega-3 plays a critical role in the development of the central nervous system (CNS). In particular, omega-3 fatty acids are an essential component of the CNS membrane phospholipid acyl chains, and are therefore critical to the structure and function of neuronal membranes.
Omega-3 may also lead to major depression through cytokine modulation. Research shows an association between depression and the production of the pro-inflammatory cytokine chemicals, which include interferon-gamma, tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta, interleukin-2 beta, and interleukin-6 beta.
How does this play a role in major depression? Well, these cytokines are documented to activate the HPA axis, lower neurotransmitter precursor availability, and influence alterations of the metabolism of neurotransmitters and neurotransmitter mRNA. In turn, high TNF-alpha and interleukin-1 beta are linked with depression severity.
Omega-3 and DHA, in particular, have been found to inhibit TNF-alpha and interleukin-1 beta levels, while omega-3 may also influence BDNF in those with various types of depression.
3. Omega-3 for Childhood Depression
Investigators studied 28 children between the ages of six and 12 years old who were randomly assigned to receive 560 milligrams (mg) to 600 mg a day of omega-3 (eicosapentaenoic acid) or a placebo for a period of four months.
Those who were treated with omega-3 showed a significant reduction in depressive symptoms starting at eight weeks of treatment, whereas the placebo-treated group failed to improve. Even though it was a pilot study, the results are quite encouraging—especially in view of the safety concerns related to the use of antidepressants in youth.
Another Childhood Study
A 12-month randomized double-blind, placebo-controlled study from 2014 found that omega-3 supplementation improved depression, anxiety, and aggression in children. Major differences in the children were apparent at the 12-month assessment and six months after the trial ended. The results indicate that long-term omega-3 treatment was influential in substantial reductions in depression for the children.
The study included 200 children between the ages 8 and 16. Half the study participants were randomized to receive one gram (g) of omega-3 with 300 mg of DHA, 400 mg of ALA, 100 mg of DPA, and 200 mg of EPA delivered in a fruit drink, while the other half of participants were given a drink without omega-3.
Another interesting finding in the study was that the parents improved their psychiatric symptoms even though they were not taking omega-3. As a result, a change in a child’s behavior was found to be partially effective through the improvement of the parent’s symptoms.
A 61% improvement in child antisocial behavior attributed to the reductions in the parent’s own emotional and behavioral issues.
4. Omega-3 for Bipolar Depression
Research also shows that omega-3 fatty acids could reduce bipolar depression symptoms. One study published in the Journal of Clinical Psychiatry in 2005 found that omega-3 may be more beneficial in the depressive phase rather than mania phase in bipolar I disorder.
For the study, 12 bipolar depression patients were treated with 1.5 g to 2 g of EPA daily for six months. Also, eight of the 10 patients had a 50% or greater reduction in depressive symptoms in a month.
Another study published in the European Journal of Clinical Nutrition in 2009 found that omega-3 fatty acid supplementation may improve depression symptoms in children and adults with bipolar disorder.
For the study, 18 children and adolescents with bipolar disorder received omega-3 supplementation with 360 mg of EPA daily and 1,560 mg daily of DHA for a six-week period. EPA and DHA blood levels were significantly higher after supplementation.
Recommended Dosage: How Much Omega-3 for Depression Is Beneficial?
This section will look at how much omega-3 fish oil may be required to treat depression symptoms.
How much EPA for depression is needed? At this time, there is not a standard recommendation for how much omega-3 fatty acids are needed each day.
Although recommendations of omega-3 and DHA and EPA range from 400 mg to 2,000 mg daily, most omega-3 fish oil supplements contain an average of 1,000 mg EPA daily in most mental health studies. It will also often take three to 12 weeks to see improvements in depression when using omega-3 fish oil.
Do not take more than a 1,000-mg dose of fish oil daily unless directed to do so by your doctor or natural health practitioner.
Also, when taking fish oil, it is important to remember that It is also possible to get too much omega-3 fatty acids from fish oil supplements. A daily dose greater than 6,000 mg of combined EPA and DHA omega-3 supplementation may increase the risk for bruising and bleeding problems, and also impair immune system function.
You should aim to get a balanced ratio of omega-6 fatty acids and omega-3 fatty acids. For instance, certain foods in your diet will work against omega-3 supplementation. Refined seed oils like corn oil, sunflower oil, and soybean oil are unnaturally high in omega-6 fatty acids, which may create an imbalance of omega-3 and omega-6 in the body.
Also, not every fish oil supplement is created equally. Most fish oils are highly processed; therefore, they can easily oxidize since omega-3 fatty acids are polyunsaturated. This means they have a low heat threshold and can easily become rancid.
You may want to consider buying fish oil supplements in triglyceride form that will also contain essential oils or antioxidants like astaxanthin that help preserve the fish oil.
10 Foods Rich in Omega-3 Fatty Acids to Stabilize Your Mood
Here are 10 of the best foods to eat for omega-3s. Please note that fish oils are the best source of DHA, the most important omega-3 fatty acid:
- Flaxseed oil
- Salmon fish oil
- Dried chia seeds
- Black and/or red caviar
- Cod liver oil
- Radish seeds
- Atlantic wild salmon
Halibut, tuna, and oysters are also rich in omega-3 and eating one or two servings of fish per week can help you get all of the omega-3 fatty acids you need to maximize its benefit in your diet. And although a number of seeds, nuts, oils and grains all feature omega-3 fatty acids, they lack the all-important DHA.
How can vegans or vegetarians get omega-3? Algal oil derived from algae is considered the best non-animal source of EPA and DHA since other plant foods contain no DHA or EPA. ALA is the main type of omega-3 found in plant-based foods; however, ALA is extremely difficult for the body to use.
Including a variety of sources is recommended and contributes to a healthy diet but getting it from fish sources—with the skin—is highly important. If the taste doesn’t suit your fancy, look for fish oil supplements (but the natural sources are better).
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