The 'Sunshine Vitamin' and Depression
Vitamin D is often referred to as the “sunshine vitamin” because it is derived from conversion to an active form from sun UV exposure. In recent years, researchers have taken an interest in Vitamin D’s role in aspects of mental health. When you understand how vitamin D affects brain function, it makes sense that Vitamin D levels could play a role in mood regulation. According to Geng et al. (2019) research has indicated that Vitamin D receptors (VDR) and Vitamin D activating enzyme are found throughout the brain, including areas in which abnormalities have been shown to correlate with depression. VDR and the enzyme responsible for converting Vitamin D to its active form in the brain have been obse
rved on neurons that produce dopamine, a neurotransmitter that affects mood, and throughout the brain in areas that play a role in mood regulation (Eyles, Smith, Kinobe, Hewison, & McGrath, 2005). Geng et al (2019) indicated a potential link between Vitamin D and the production of serotonin, another neurotransmitter involved in mood regulation. They also point out extensive research demonstrating the role of Vitamin D in modulating neurotrophic agents, chemicals in the brain essential for neuronal development and associated with psychiatric illness if functioning abnormally.
Studies have demonstrated a potential link between depression and low circulating Vitamin D levels. In a cohort study involving participants over the age of 65, Vitamin D levels were measured at baseline and again at 3- and 6-year intervals. The study indicated a correlation between low Vitamin D levels and the development of depressive symptoms, with the association more pronounced in the female subjects (Milaneschi, et al., 2010). Another cohort study involving Japanese workers demonstrated a link between lower Vitamin D levels and the presence of depressive symptoms. (Mizoue et al., 2014).
Despite an evident link between Vitamin D levels and mood, Vitamin D supplementation is not a standard treatment for depression or other mood disorders. Not only are studies on intervention with Vitamin D for mood disorders relatively limited (Bouillon, 2021), but researchers have suggested that Vitamin D intervention study results have been difficult to compare because of a great deal of inconsistency between studies, including type and dose of Vitamin D supplement used, duration of the studies, the specific population being studied, control groups, etc. (Choukri, Conner, Haszard, Harper, & Houghton, 2018, Shaffer et al., 2014).
A systematic review and meta-analysis of several randomized control trials were conducted by Shaffer et al. in 2014 and concluded that Vitamin D supplementation could be useful for helping patients with clinically significant depression. Interestingly, in five of the seven studies they reviewed, researchers did not recruit participants with depression or even excluded participants with depression, either treated or untreated. In their analysis of the studies that did recruit subjects with depression, they found that the positive effects of Vitamin D were statistically significant. Also interesting, Shaffer et al. found that in the four studies whose participants had sufficient baseline Vitamin D levels, the reduction in depressive symptoms was greater than in the three studies whose participants’ baseline Vitamin D levels were insufficient.
The general consensus among researchers is that additional studies are necessary to determine the potential benefit of Vitamin D supplementation for mood symptoms and/or to further elucidate the connection between Vitamin D supplementation and mental health (Choukri, Conner, Haszard, Harper, & Houghton, 2018, Shaffer et al., 2014, Bouillon, 2021).
While the jury is still out on Vitamin D supplementation as an effective treatment for depression, I am hopeful that future studies may offer less ambiguous evidence in support of Vitamin D for this purpose. For different reasons, clients might see the potential benefit of taking natural supplements in addition to or instead of pharmaceuticals. Those already on multiple medications for physical reasons may want to avoid polypharmacy and risk for medication interactions. Some people may have had adverse reactions to medications in the past and are hesitant for that reason. Others may, in general, simply appreciate a more holistic approach to care. If the potential exists to alleviate the suffering caused by depression among those who are hesitant to consider pharmaceuticals but open to more natural options, like Vitamin D, then in my humble opinion, these options would certainly be worth researching further, so their use can be backed by sufficient evidence.
Bouillon, R. (2021). Vitamin D and extraskeletal health. UpToDate. Retrieved from https://www.uptodate.com/contents/vitamin-d-and-extraskeletal-health?search=vitamin%20d%20depression&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2#H651690
Choukri, M.A., Conner, T.S., Haszard, J.J., Harper, M.J., Houghton, L.A. (2018). Effect of vitamin D supplementation on depressive symptoms and psychological wellbeing in healthy adult women: a double-blind randomised controlled clinical trial. Journal of Nutritional Science. 7(e23). doi: 10.1017/jns.2018.14.
Eyles DW, Smith S, Kinobe R, Hewison M, McGrath JJ. (2005). Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain. Journal of Chemical Neuroanatomy. 29(1), 21-30.
Geng C, Shaikh AS, Han W, Chen D, Guo Y, Jiang P. (2019). Vitamin D and depression: mechanisms, determination and application. Asia Pacific Journal of Clinical Nutrition. 28(4), 689-694.
Milaneschi Y, Shardell M, Corsi AM, Vazzana R, Bandinelli S, Guralnik JM, Ferrucci L. (2010) Serum 25-hydroxyvitamin D and depressive symptoms in older women and men. The Journal of Clinical Endocrinology & Metobolism. 95(7), 3225-3233.
Mizoue T, Kochi T, Akter S, Eguchi M, Kurotani K, Tsuruoka H, Kuwahara K, Ito R, Kabe I, Nanri A. (2015). Low serum 25-hydroxyvitamin D concentrations are associated with increased likelihood of having depressive symptoms among Japanese workers. Journal of Nutrition 145(3), 541-546.
Shaffer, J.A., Edmonson, D., Wasson, L.T., Falzon, L., Homma, K. Ezeokoli, N., Li, P. &, Davidson, K.W. (2014). Vitamin D supplementation for depressive symptoms: a systematic review and meta-analysis of randomized control trials. Psychosomatic Medicine, 76(3), 190-196.