Getting the ‘blues’ is normal.
We all feel fed up, miserable and sad at certain times in our lives but most of the time these feelings don’t last. Typically they pass on their own or with a little help from some self-reflection or talking it out with a friend.
Clinical depression is different; it is the more-severe form of depression, also known as major depression or major depressive disorder (MDD). It isn’t the same as depression caused by a loss, such as the death of a loved one, or a medical condition, such as a thyroid disorder.
With MDD, depressive feelings don’t easily improve and may last for weeks, months or even years.
Symptoms are typically brutal; usually severe enough to cause noticeable problems in relationships with others or in day-to-day activities, such as work, school or social interactions. Clinical depression can affect people of any age, including children.
However, symptoms of clinical depression, even if severe, typically improve with psychological counseling, antidepressant medications or a combination of the two.
Because ‘psychology’ is not a simple issue with biological functioning, talk therapy, cognitive-behavioural techniques etc should be part of the standard care for depression but sadly, most people are just put on medication.
But what about nutrients? Can they help to prevent or improve depression? In a word yes. Nutrients support the very biochemistry that the production of neurotransmitters are made from, as well as, lower inflammation & oxidation; major drivers of mood disorders including depression (1, 2, 3, 4).
For more, see my other post 9 Nutrient Deficiencies That Can Cause Depression.
What’s the association between vitamin D and depression?
Like with all research, there is some evidence that supports vitamin D’s role in preventing and improving depression and other studies that don’t. Early research that looked at the associations of vitamin D in the blood found that those with lower concentrations had greater rates of and risk for depression.
The obvious question was; did the low vitamin D cause the depression or did the depression result in low vitamin D? (less sun exposure/going outside less, poor appetite, eating less foods with vitamin D, or stopping vitamin D supplementation as depression progressed?).
To be able to say with confidence that vitamin D helps with depression, we need studies to show that depression can be prevented and/or treated by improving vitamin D concentration in the first place.
Does vitamin D help with depression?
Vitamin D receptors have been found in many parts of the brain (5). Receptors are like docking stations and are found on the surface of cells, as well as, on the genes inside of cells. A receptor’s job is to allow chemical signals (molecules) to attach to a cell or a gene.
When the right molecule docks with the right receptor, the molecule instructs the cell or the gene to do something [increase or decrease some kind of activity or function]; this happens all the time in brain cells, or neurons.
Many of the vitamin D receptors in the brain are found in areas that are linked to the development of depression (especially the amygdala – the part of the brain that regulates emotion – which has loads of vitamin D receptors).
There are vitamin D receptors near the synapses as well; the point of communication between brain cells. When the synaptic connection is strong and working well, moods tend to be better and better balanced.
For this reason, vitamin D has been linked with depression and with other mental health problems as well including anxiety, ADHD, dementia, schizophrenia, dipolar disorder etc.
We’re not entirely sure how vitamin D works in the brain to support healthy moods. One theory is the well-known fact that vitamin D is needed for the production of certain types of neurotransmitters (monoamines), such as serotonin, and vitamin D influences how those neurotransmitters work (6).
Many anti-depressant medications (and nutrients) work by supporting the brain to make monoamines which can help to prevent and treat depression (7).
Vitamin D works in a similar way and has been shown to support anti-depressant treatment (8).
Vitamin D has been shown to support & strengthen synaptic communication, as well as, temper inflammation which has been shown to be an independent risk factor for depression (9). By preventing the immune system from becoming over-reactive, vitamin D prevents the immune cells from producing too many pro-inflammatory chemicals called cytokines.
What does the research say about vitamin D and depression?
Research on vitamin D and depression, as well as other mental health problems, is rapidly growing.
It’s only recently that large scaled studies on vitamin D and depression have been conducted. But the research in this area has given some conflicting results.(10)
A 2013 randomized study (the kind of study design we get excited about), looked at the impact of just 1500 IU of vitamin D as supporting treatment to the antidepressant fluoxetine (Prozac). They found that by week 4, the vitamin D + fluoxetine combination was significantly better than fluoxetine alone in controlling depressive symptoms.
One of the challenges with this study is that we don’t know what the vitamin D concentrations were in subjects at the start of the study, or by week 4 or week 8. Was vitamin D only effective in those who were severely deficient? Was 1500 IU helpful for those less deficient?
A research study from Norway  found that people with a low concentration of vitamin D in their blood had more symptoms of depression.
It also found that taking vitamin D, particularly in large amounts (the equivalent of 5700 IU per day for 6 months), improved symptoms of depression with the biggest effect in those people with the most severe symptoms.
A study in the Netherlands that looked at a group of people with confirmed major depressive disorder found that they all had lower vitamin D concentrations. It also found that those with former, but not current, depression had lower symptom severity if they had higher vitamin D levels.
There was also a significant correlation between vitamin D status and developing depressive symptoms at a 2-year follow up; in other words there was less risk of developing depression if vitamin D concentration were ideal.
Enough with the details, what’s the bottom line?!
- There’s no doubt vitamin D plays a positive role in supporting health moods including depression
- The brain has loads of vitamin D receptors that are hungry & waiting for vitamin D to show up and do it’s job
- Most people are deficient in vitamin D so getting more just makes good sense
- Those who are the most deficient stand to see the greatest benefit so responses to vitamin D supplementation will vary
- The effects of vitamin D to support moods, including depression, can take a while since it takes up to 10 weeks for vitamin D concentrations to peak & level off and then a bit of time for our ‘biochemistry’ to balance out
- The exact dose of vitamin D and optimal vitamin D blood concentration is unknown which is why testing is best; there is a lot of variation in response between people given the same dose of vitamin D. The bulk of the evidence suggests aiming for 80 nmol or slightly higher, a health practitioner can determine the best dose for you to achieve this target.
For more research on the role of vitamin D in depression, check out Vitamindwiki’s page on depression.
Doug Cook RDN is a Toronto based integrative and functional nutritionist and dietitian with a focus on digestive, gut, and mental health. Follow me on Facebook, Instagram and Twitter.