Does Vitamin D deficiency cause depression? Can some cases of depression be treated with Vitamin D?
The truth is, we don’t know. The research has been lacking and thoroughly inconclusive. Even the best studies would still have trouble pinning down the relationship between vitamin D and depression — after all, depression has never been a straight-forward health problem.
What is depression? To a large extent, that depends on who you ask. We’re all familiar with feeling depressed after events like a breakup or the loss of a loved one. Many people are familiar with the idea of chronic depression, or maybe even with bipolar depression. People living in northern climates are likely to have heard of seasonal affective disorder (SAD), a seasonal depression that is most common in the winter.
Depression is categorized by symptoms, rather than causes. It’s difficult to know how best to treat a person’s depression. Cognitive therapy is helpful for many cases of depression, while light box therapy is only typical for treatment of SAD. Antidepressants may be useful treatment for all kinds of depression, including SAD, but antidepressants often don’t treat the underlying cause and come with many risks, such as increased depression.
Oftentimes, we don’t really know the cause of a particular case of depression.
So it’s not surprising that such a broad statement as “vitamin D treats depression” would be difficult to prove.
We know that there is a correlation between vitamin D and general depression. A study published this month in the British Journal of Nutrition showed an increased risk of depression for the lowest quartile vitamin D blood serum levels.1 The study had a sample size of over 5000 and adjusted for many factors, including lifestyle. Of course, this isn’t the first study suggesting a relationship between vitamin D and depression2,3,4, but it’s likely the largest. When you think about it, though, it’s not surprising. Though you may or may not have heard of seasonal affect disorder, most people are familiar with the concept of winter blues. The winter is a cold and depressing time for many people, and it’s also when we get the least vitamin D. Sure, that’s not proof of a definitive causal relationship, but it suggests a need for further research on the relationship between vitamin D and depression.
At least one trial has suggested that high-dosage supplementation of vitamin D for patients with SAD may be a more effective treatment than light therapy.5
Maybe vitamin D deficiency can cause depression, maybe not. But at the very least, the numbers suggest that people with depression should be mindful of their vitamin D needs.
References
1: Higher Serum 25-hydroxyvitamin D concentrations are related to a reduced risk of depression
2: Association of vitamin D levels with incident depression among a general cardiovascular population
3: Serum 25-Hydroxyvitamin D Concentrations and Depressive Symptoms among Young Adult Men and Women
4: Vitamin D deficiency is associated with anxiety and depression in fibromyalgia
5: Vitamin D vs broad spectrum phototherapy in the treatment of seasonal affective disorder