Depression and omega-3 fatty acids
Opportunities for people with depression?
Depression is one of the most common mental illnesses worldwide and poses major challenges for both those affected and healthcare systems. Since not all patients respond adequately to psychotherapy or medication, complementary approaches are coming into focus. Omega-3 fatty acids in particular are being intensively discussed as a supportive option due to their potential anti-inflammatory and neuroprotective properties.
How does depression develop? What happens in the brain?
Depression does not arise from a single cause, but rather from a combination of various factors—such as genetic predisposition, physical changes in the brain, or external influences such as stress.
Previously, the prevailing view was that an imbalance of certain neurotransmitters in the brain—such as serotonin, norepinephrine, and dopamine—was primarily responsible. Today, we know that other processes can also play an important role:
Disruptions in signal transmission between nerve cells: Systems that work with the neurotransmitter glutamate (stimulating) and the neurotransmitter gamma-aminobutyric acid (GABA) (inhibitory) can become unbalanced.
Changes in the brain: In cases of depression, it has been shown that certain areas such as the hippocampus can shrink or that the connections between nerve cells become less stable.
Fewer “nerve growth factors”: Proteins such as BDNF (brain-derived neurotrophic factor), which normally protect nerve cells and promote new connections, may be reduced in depression. This can limit the brain’s ability to adapt.
Stress: Chronic stress can lead to an overproduction of stress hormones (e.g., cortisol). This can potentially increase susceptibility to depression.
Inflammation in the body: People with depression often have elevated levels of certain inflammatory messengers. These can potentially promote inflammation in the brain and damage nerve cells.
Oxidative stress: When the balance between harmful oxygen compounds (free radicals) and the body’s own protective mechanisms is disrupted, cells can be damaged. This may contribute to changes in the brain.
All these factors together can cause the brain to lose flexibility (“neuroplasticity”), form fewer new nerve cells, and become more sensitive to stress—processes that can contribute to the development and maintenance of depression.
Possible Symptoms:
- Loss of appetite
- joylessness
- Quick fatigue
- Reduced concentration
- Listlessness
- Depressed mood
- Feelings of guilt
- Sleep disorders
Omega-3 fatty acids – what are they and why are they important?
Omega-3 fatty acids are polyunsaturated fatty acids that our bodies can only produce in limited quantities. That is why we should consume them regularly through our diet.
There are three main forms of omega-3 fatty acids:
ALA (alpha-linolenic acid): This fatty acid is found primarily in vegetable oils such as flaxseed oil, rapeseed oil, and walnut oil, as well as in nuts and seeds. Since our bodies cannot produce ALA on their own, this fatty acid is considered essential.
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid): These are found primarily in fatty fish such as salmon, herring, and mackerel, as well as in algae, which are the actual producers of these fatty acids. The body can also produce these fatty acids to a limited extent from ALA, if it is available. This is why EPA and DHA are referred to as semi-essential. A high proportion of omega-6 fatty acids, especially linoleic acid (LA), as is often found in Western diets, can further inhibit the conversion of ALA to EPA and DHA.
How do omega-3 fatty acids work in the brain?
Omega-3 fatty acids are an important part of the brain’s structure—around 10 to 15% of an adult human brain consists of DHA. Researchers believe that omega-3 fatty acids have a positive effect on brain function on several levels, particularly on processes that can also be altered in depression:
- Anti-inflammatory: They reduce certain messenger substances in the body that are associated with inflammation and depression.
- Support for messenger substances in the brain: Omega-3 fatty acids influence important systems such as serotonin and dopamine, which are colloquially referred to as “happiness hormones” and are crucial for mood and motivation.
- Promotion of brain plasticity: DHA in particular supports the formation of new connections between nerve cells and strengthens the brain’s adaptability.
- Protection against stress and oxidative damage: Omega-3 fatty acids can help reduce the harmful effects of stress hormones and free radicals on the brain.
In addition, EPA and DHA have different effects:
- EPA has primarily anti-inflammatory and vascular protective properties.
- DHA is a key component of nerve cell membranes and supports the formation of new connections in the brain (synapses).
Omega-3 fatty acids and their connection to depression
Several large studies have shown that people who consume large amounts of omega-3 fatty acids—especially from plant sources such as flaxseed oil (ALA) or by eating fatty sea fish (EPA and DHA)—have a lower risk of developing depression. This effect seems to be particularly pronounced in women, especially after menopause.
However, other studies have produced mixed results: some studies have been unable to establish a clear link between fish consumption and depression, while plant-based omega-3 fatty acids (ALA) continue to be associated with a lower risk. Even in people who had already experienced depression, additional intake of omega-3 fatty acids had a positive effect on mood and thinking, but did not always improve depression as a whole.
It is also interesting to note that differences between regions were observed: on the Torres Strait Islands, an archipelago near Australia, high consumption of fresh fish was associated with fewer depressive symptoms – so here, it seems that the quality and availability of food and local or geographical influences play a particularly important role. However, as is so often the case, definitive evidence is currently lacking.
In summary, however, it must be taken into account that depression is a multifactorial event. Although nutrition can probably play a role, social and psychological factors, lifestyle, physical activity, sun exposure, genetic predisposition, and many other influences also contribute to the development and course of depressive disorders.
How common is depression in Germany?
- 8,2 % der Erwachsene (ca. 5,3 Mio.) zwischen 18-79 Jahren sind jährlich betroffen.
- Approximately one in five to six people will suffer from depression at some point in their lives.
- Women are affected twice as often as men.
Omega-3 fatty acids in practice – recommendations for everyday life
Fats are a natural part of our diet. However, it is important to consider the types of fats we consume. Polyunsaturated fatty acids are particularly beneficial to our health.
According to the German Nutrition Society (DGE), adolescents and adults should consume 7–10% of their daily calories in the form of polyunsaturated fatty acids. With an average energy intake of 2000 kcal/day, this corresponds to, for example:
• 1 tablespoon rapeseed/walnut oil + 1 tablespoon linseed oil or
• 1 tablespoon vegetable oil + a small handful (approx. 25 g) of walnuts or seeds or
• one to two portions (approx. 120 g) of fatty fish per week (e.g., salmon/herring/mackerel)
It is important to maintain a balance between omega-6 and omega-3 fatty acids. In everyday life, this means using rapeseed, linseed, or walnut oil more often and consuming sunflower or corn oil and highly processed ready-made products less frequently. This helps maintain the fatty acid balance.
You can find more information on this topic here: Fats
DHA is important for pregnant women and infants as it supports the development of the child’s brain. One to two portions of fatty fish per week or, alternatively, algae oil or fish oil capsules reliably cover the minimum requirement of 200 mg/day.
The European Food Safety Authority (EFSA) makes similar recommendations and also emphasizes that a daily intake of 250 mg of long-chain omega-3 fatty acids can reduce the risk of heart disease in adults.
Dietary supplements as therapy – yes or no?
Some studies show that omega-3 fatty acid supplements can enhance the effect of antidepressants and further alleviate symptoms. However, the results are not always clear-cut—some studies found only minor differences or none at all.
Omega-3 fatty acid supplements (e.g., fish oil or algae oil capsules) are generally considered safe and are usually well tolerated; but mild gastrointestinal complaints can sometimes occur. In high doses—especially in people with cardiovascular disease—they can increase the risk of cardiac arrhythmia or an increased tendency to bleed. According to a report by the German Federal Institute for Drugs and Medical Devices, the risk of atrial fibrillation is highest at a dose of 4 g/day. Therefore, if you have an underlying condition, you should definitely consult your doctor before taking it.
Current guidelines for the treatment of depression do not recommend routine use of dietary supplements if there is no proven deficiency. Instead, a balanced diet with sufficient vegetable oils, nuts, and regular fish consumption is recommended.
Conclusion for consumers
Omega-3 fatty acids are important building blocks for the brain and nerve cells. They support signal transmission, have anti-inflammatory effects, and may help reduce the risk of depression, especially in women.
Although studies to date provide some evidence, the results are not always clear-cut. It is therefore not currently possible to make a general recommendation for taking omega-3 fatty acid supplements in connection with depression. However, a balanced diet with regular consumption of fatty sea fish or plant sources such as flaxseed or rapeseed oil is advisable.
Help and further information on the subject of depression is available, for example, from the German Depression Aid and Suicide Prevention Foundation.
Acknowledgements
Many thanks to Münster University of Applied Sciences, in particular Janina Dapprich, Prof. Dr. oec. troph. Anja Markant, and Prof. Dr. rer. medic. Tobias Fischer, for writing this article as part of the “Nutrient Compass” project.
