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Introduction

The world health organization (WHO) has recently stated that major depression is now the second largest cause of incapacity (physical or mental inability).

It is estimated that ~15% of women, and ~6% of men, will suffer from major depression at some point during their life.

There are many causes of depression, and nutrition is one that is certainly contributing, with most people being overfed and undernourished to adequately support brain function.

Mixed together with poor sleep, alcohol consumption, smoking, and a lack of physical activity, and it is not surprising why depression is now such a common disorder.

The mechanisms by which nutrition may lead to depression are:

  • Inadequate intake of energy and essential vitamins and minerals
  • Compromised gut and immune system
  • Poor antioxidant defense system that cannot defend against chronic inflammation
  • Lack of neurotrophic factor production which is needed for plasticity and neuronal maintenance

As much as a healthy balanced diet should be the number 1 goal for fighting depression alongside counseling and antidepressant medications, some dietary supplements may also help to treat or improve the issue.

1. Omega-3 Fatty Acids

Omega-3 fatty acids are essential types of dietary fats that need to be consumed in the diet as they cannot be synthesized in the body from other molecules.

They are extremely important for brain function as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two forms of omega-3’s, are key components of cell membranes. DHA represents ~15% of all the types of fat found in the brain.

Omega-3’s support the cell membranes fluidity, influence the functioning of neurotransmission [1], and aid calcium flow through the calcium channels [2].

As DHA is the largest contributor to these functions, it is then one which is most associated with the protective role of omega-3 in depressive symptoms.

Although EPA does play an important and often overlooked role in balancing neuronal and immune functioning by reducing the arachidonic acid component (pro-inflammatory omega-6) of the membrane.

Just from looking at various world populations, it is clear that societies with the highest consumption of omega-3’s have the lower incidence of depression [3].

In addition, patients with major depression tend to have an abnormal composition of fatty acids in their cell membranes, favouring pro-inflammatory omega-6 as opposed to anti-inflammatory omega-3 [4].

This is why health associations are making the effort to point out the importance of the type of polyunsaturated fats people are eating, and how it is an important physiological determinant of mental health.

In terms of supplementing with omega-3 to improve mental function, this is now considered a potential antidepressant treatment option as it may effectively reduce the amount of chronic inflammation occurring in the brain of depressive patients.

The most recent scientific reviews assessing the extent of benefit of omega-3’s on depression state that they give “mild to moderate benefit” for improving depressive symptoms [5].

2. Folate

Consuming an adequate amount of folate has shown to be a protector against the development of depressive symptoms [6].

A deficiency in folate is causally related to depression as it has an important role in methylation processes (transforming folate to methylfolate), which is a necessary step in order to synthesize neurotransmitters in the central nervous system.

When folate is supplemented during antidepressive treatment, it has been correlated to an increase in blood folate levels and with a greater decrease in the hamilton depression scale score [7].

If people are going to supplement with folate, l-methylfolate is the best option, as this is the active form which is capable of crossing the blood-brain barrier and helping to synthesize dopamine, adrenaline, and serotonin [8].

3. S-Adenosyl-Methionine

S-adenosyl-methionine is the active sulfonium form of methionine, which is an essential amino acid.

It is significantly involved in a metabolic pathway called the methylation cycle, which regulates gene expression, DNA repair, inflammation, and neurotransmitter activity.

Under normal circumstances, methionine is synthesized from folic acid and homocysteine, which can then go on to be metabolized into s-adenosyl-methionine.

It has been verified in many studies that patients suffering from depression typically will have low levels of s-adenosyl-methionine in their cerebrospinal fluid (the liquid around the brain and spinal cord).

The antidepressive effect of s-adenosyl-methionine is based on how it can alter the neuronal membrane fluidity and effect the functionality of certain membrane proteins [9].

Supplementation with s-adenoysl-methionine has shown to be extremely powerful at acting as an  antidepressant, but only in the case of male patients [10].

However, a recent scientific review states that there is still not enough scientific evidence to conclude that s-adenosyl-methionine supplementation is beneficial for adults, and that there is a need for future high quality evidence to be obtained [11].

4. Magnesium

Magnesium is a mineral that acts as a cofactor in multiple enzyme reactions within cardiovascular, endocrine, osteoarticular, and nervous systems.

Regarding depression, magnesium acts on the level of the nervous system by affecting different biochemical processes such as maintaining the fluidity of the neuronal membrane.

A lot of data reveals that magnesium deficiencies lead to many psychiatric manifestations such as seizures, headaches, anxiety, insomnia, tiredness, and depression [12].

There is even now a well-recognized inverse relationship between magnesium intake and depressive symptoms [13]. Blood magnesium levels in depressive patients are also correlated to the intensity of clinical depressive symptoms [14].

It is thought that a sustained deficiency of magnesium in the diet is associated with activation of inflammatory processes which may not cause depression, but will certainly worsen depressive symptoms [15].

For example, a lack of magnesium allows calcium and sodium ions to move into the postsynaptic neuron, and for potassium ions to move out, which causes reactive oxygen species to damage neurons.

In regards to the use of magnesium supplements, there appear to be favorable results in animal models of depression that demonstrate the potential clinical application of magnesium supplementation for depression in humans [16].

However, there is currently a lack of clinical human trials to strongly advocate the use of magnesium supplements for depression (but could be worth a try!).

Conclusion

People suffering from depression often look towards drugs and supplements to act as that “quick fix” to their problems, however only a few products are able to actually benefit such a complicated condition.

The most well-researched and beneficial supplements that may reduce depressive symptoms are omega-3 fatty acids, folate, s-adenosyl-methionine, and magnesium.

However, far more clinical human research is needed in this supplementation category and there is not yet a definitive cure for depression through supplementation.

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This article has been reviewed and fact-checked by a certified nutritionist, and only uses information from credible academic sources.