Although low mood may look like a minor problem on the outside, it can seriously impact your well-being and daily functioning. A low or depressed mood may be a sign of a bigger problem, such as major depressive disorder or, simply put - depression.
According to the National Institute of Mental Health, more than 7% of all Americans have had at least one major depressive episode in their life, and in 64% of the cases, this led to severe impairment of their quality of life and increased risk of suicide.
Interestingly, depression often occurs during the darker and colder months, specifically during the winter. This has led scientists to believe there may be a connection between sun exposure and depressive symptoms.
The best candidate to explain this link is low vitamin D levels. The sunshine vitamin is produced in your skin under the effect of direct sunlight, and its deficiency affects almost half of the world's population.
More and more studies report that vitamin D deficiency is related to problems with mental health, low mood, depression, and anxiety disorders, while supplementation may improve these complaints.
Keep reading to discover more about the relationship between low vitamin D levels and your mood, brain function, and possible symptoms of depression.
If you are experiencing any form of emotional distress, don't hesitate to contact SAMHSA's National Helpline or National Suicide Prevention Lifeline, where you can receive free and confidential support.
What does vitamin D do?
Vitamin D is a fat-soluble vitamin that's also often classified as a prohormone since food is not its only source.
Your body can produce the vitamin on its own when your skin is exposed to direct sunlight or another source of UV-B radiation. The rays help break down cholesterol, leading to the formation of Vitamin D3 (1).
The sunshine vitamin is most well known for its role in controlling calcium levels and bone health. Its deficiency can lead to weak bones, deformities, and disability.
Vitamin D also supports the function of the immune system. Thus, a deficiency may increase your susceptibility to infections.
Moreover, studies reveal that almost all tissues in the human body have receptors for vitamin D (VDR) (2).
The central nervous system is no exception - vitamin D receptors are widely distributed in several brain regions, including the amygdala, the hippocampus, and the hypothalamus. These zones also control your mood and emotions.
Studies have shown that vitamin D plays a crucial role in the normal function of the hippocampus - an area often associated with mood disorders and mental health issues (3).
The vitamin levels fluctuate according to the seasonal changes in sun exposure. Therefore, scientists consider that low levels may play a role in conditions such as seasonal depression or Seasonal affective disorder (SAD) (4).
The latter leads to depression symptoms and lack of energy, usually appearing during late fall or early winter and going away during spring and summer.
How does vitamin D affect mood?
Vitamin D and neurotransmitters
Although scientists have proven the presence of VDR in the brain, including the areas that control mood and emotions, the exact mechanism of vitamin D's effect is not fully understood.
Some scientists have suggested that vitamin D insufficiency may affect neurotransmitters in the brain, such as serotonin and dopamine, which play a central role in low mood, anxiety disorder, and depression.
Low serotonin is implicated as one of the leading theories for the pathogenesis of depression, and drugs that can increase serotonin levels are commonly prescribed as antidepressant medication (5).
However, clinical trials showing a link between vitamin D deficiency, supplementation, and depression do not support that the effects are mediated via changes in serotonin levels (6).
On the other hand, researchers have shown that vitamin D is essential for the normal functioning of dopaminergic neurons (7).
If dopamine levels are insufficient, it may lead to mood problems, including depressed mood, lack of motivation, and feelings of hopelessness.
Moreover, the neurotransmitter is considered to play a central role in developing the most common type of depression - major depressive disorder (8).
Vitamin D and Neurotrophic Factors
Vitamin D is a potent modulator of the expression of neurotrophic agents in the brain, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF) (9).
Neurotrophic factors are biomolecules in the brain essential for neurons' survival, growth, and functioning.
They are thought to play a central role in a process called neuroplasticity. That's the ability of the brain to adapt, learn and repair.
It includes functional neuroplasticity (formation of new connections- synapses between the neurons) and structural neuroplasticity (cortical remapping) (10).
For example, research reveals that BDNF might stimulate neurogenesis, which is the formation of new neurons in parts of the adult brain that retain stem cells (11).
Additionally, BDNF plays a vital role in the long-term survival, differentiation, and functioning of neurons in the hippocampus.
Therefore, vitamin D may support your mood and reduce depression symptoms by upregulating BDNF and thus supporting the function of your hippocampus.
On the other hand, vitamin D also upregulates GDNF which is crucial for the survival of dopaminergic neurons (12). This may also be one of the underlying mechanisms for the benefits of vitamin D for major depressive disorders.
Can a lack of vitamin D cause mood swings or depression?
Researchers first reported lower vitamin D status related to poor mood and depressive symptoms in 1979 (13). Since then, several epidemiological studies have confirmed that link.
In another study from 2014, 615 young adults were split into 4 groups according to their vitamin D status (14). The participants in the group with the lowest vitamin D levels were more likely to report depressive symptoms than those with the highest vitamin D levels.
Furthermore, a survey of 1 282 elderly also found that the levels of the sunshine vitamin are about 14% lower in individuals with minor depression or major depressive disorder compared to their healthy peers (15).
One of the most extensive observational studies was conducted amongst 7 358 older adults with cardiovascular diseases. They reported that the incidence of depression was relatively high amongst all participants except those with adequate vitamin D levels of at least 50 ng/ml (125 nmol/l) or above (16).
These are relatively high vitamin D levels, considering that scientists consider levels above 30 ng/ml (75nmol/l) as optimal, under 30 ng/ml as insufficient, and 20 ng/ml (50nmol/l) as a sign of a deficiency.
The largest trial so far included almost 8 000 participants and revealed that patients with serum vitamin D above 30 ng/ml are at a significantly lower risk of depressive episodes and improved mental health compared to those with vitamin D deficiency (<20 ng/ml) (17).
Does supplementation improve mood?
Several randomized and controlled clinical trials have shown that vitamin D supplementation may improve mental health, mood, and depression symptoms in individuals with a deficiency.
In 54 adolescents with depression, 3 months of vitamin D supplementation (2 000 - 4 000 IU per day) led to an increase in serum vitamin D levels from 16 ng/ml (40 nmol/l) to 36 ng/ml (90 nmol/l) on average and significantly improved their symptoms (18).
Vitamin D supplementation appears effective in older adults as well. One study in 78 elderly patients with moderate to severe depression reported that 50 000 IU of vitamin D3 weekly for 8 weeks led to a significant reduction in complaints compared to a placebo (19).
In the 8th week, the mean vitamin D levels of the intervention group were over 43 ng/ml.
Furthermore, a study of 50 women with type 2 diabetes, vitamin D deficiency and depression reported that 50 000 IU of vitamin D per week improved symptoms of both depression and anxiety disorder (20).
Another study in 46 patients with significant depression and concurrent Vitamin D deficiency revealed that a single bolus dose of 300 000 IU as an injection significantly improved mental health, mood, depressive symptoms, and quality of life 12 weeks after the dose (21).
A similar dosage was also influential in improving mental health, mood, and scores of depression in 90 patients with ulcerative colitis (22).
The largest randomized trial so far included 441 obese individuals, Those with vitamin D levels under 16 ng/ml had much higher scores on tests for depression than the rest (23).
Compared to a placebo, 1 year of supplementation with up to 40 000 IU of vitamin D per week led to a significant reduction in the scores of depression, improved mental health, and an increase in vitamin D levels above 40 ng/ml in the majority of obese patients.
Keep in mind that a supplement is not a substitute for medical treatment. You should always consult a doctor and avoid discontinuing your medication therapy without medical approval.
In addition, you may also consider other treatments, including cognitive behavioral therapy, talk therapy, and physical therapy.
How much Vitamin D per day should you take to improve your mood?
According to most evidence, achieving serum vitamin D levels above 30 ng/ml appears to be most beneficial for mental health, mood, and depressive symptoms.
Most studies have used larger bolus dosages, such as once per week or once per month, as it eventually leads to higher serum vitamin D levels. That's because vitamin D is a fat-soluble vitamin that your body can store.
On the other hand, studies report that daily dosage leads to a faster increase in serum vitamin D levels compared to bolus (24).
If you are deficient, the Endocrine Society recommends 1 500 to 2 000 IU doses to achieve and maintain serum levels above 30 ng/ml (25).
Furthermore, there is an adverse association between body mass index and response to vitamin D supplementation (26).
Overweight and obese individuals accumulate more vitamin D in their fatty tissue, reducing supplementation's effect on their serum levels.
Therefore, overweight and obese individuals may need a vitamin D supplement with at least 4 000 IU to achieve optimal vitamin D status.
For example, in one study on 68 depressed and overweight (BMI=27.3 ± 2.3) patients with type 2 diabetes, it took 12 weeks of daily supplementation with 4 000 IU vitamin D to raise serum levels from 15.5 ± 8.8 to 32.2 ± 8.9 ng/ml (27).
Patients also experienced a significant improvement in their mental health, mood, and anxiety disorder symptoms.
Best vitamin D supplement for depression and mental health?
Currently, two primary forms of vitamin D are available as a supplement - vitamin D3 and vitamin D2.
Vitamin D2 sources include plants such as mushrooms, while you can find vitamin D3 in animals and animal food sources such as fish, eggs, and algae.
According to a meta-analysis of 7 studies, vitamin D3 has better bioavailability than vitamin D2, leading to a more reliable increase in serum concentrations (28).
D2 appears to be a less stable form of the vitamin, so researchers suggest that it may have reduced shelf-life as a supplement (29).
Therefore, most experts recommend supplementing with vitamin D3 to increase serum levels more reliably.
It's important to supplement with adequate doses of vitamin D and choose a reliable supplement.
Vtamin D3 + K2 by Nutririse, has unmatched potency with 5 000 IU of vitamin D per serving. The dose should be sufficient to increase serum vitamin D level above 30 ng/ml in several weeks, depending on the individual.
Keep in mind that experts consider 10 000 IU per day as the maximum safe upper limit for supplementation to avoid vitamin D toxicity.. D3 + K2 by Nutririse also contains 100 mcg of vitamin K2, 210 mg of calcium, and 5 mg of black pepper extract (Bioperine).
Adding K2 reduces the risks of hypercalcemia since it pulls the calcium into the bones, where it belongs. According to studies, combining vitamin D3 and K2 may have a synergistic benefit for bone health and bone mass density (30).
Vitamin D and depression are interlinked in many ways we do not yet fully understand. Still, fortunately, you can improve low levels quickly by getting more exposure to sunlight and taking a quality vitamin d supplement.
Note: This article is for informational purposes only, and not intended for use as medical advice. Always consult your healthcare provider before starting any dietary supplement.