Publish Date

March 24, 2013

Vitamin D was thought to be of use only in preventing rickets and osteomalacia. Accumulating evidence, however, has demonstrated that vitamin D does much more, influencing the health and function of tissues and organs throughout the body. Vitamin D is an important nutrient for our physical health, but many people are unaware of how critical this vitamin is for maintaining our mental health. In this article, we will explore the evidence-based research on vitamin D and depression. The next article will explore the effects of vitamin D on psychosis and schizophrenia.

Vitamin D is categorized as a hormone because of its paracrine, autocrine, and endocrine functions, and it can be acquired through food or exposure to the sun. Vitamin D can be found in high amounts in fatty fish and also in milk, yogurt, orange juice and cereals, and dietary supplements. A sufficient amount of vitamin D can also be produced from 5-15 minutes of daily exposure to sunlight.

Vitamin D2, or ergocalciferol, is only made by plants and vitamin D3, or cholecalciferol, is created when ultraviolet light hitting the skin photochemically converts cholesterol to vitamin D. Serum 25-hydroxyvitamin D [25(OH)D] is a biological marker used to reliably measure the levels of both forms of vitamin D. Among its many functions, vitamin D is important for absorbing calcium, maintaining calcium homeostasis in tissues, growth of bones and teeth, properly functioning neurons and glial cells, preventing rickets and osteomalacia, influencing tissues and organs, preventing psoriasis, muscle pain, weakness, elevated blood pressure, some forms of cancer, and autoimmune disease, and preserving mental health.

Recent studies have advanced our understanding of vitamin D and its effect on the brain. There are vitamin D receptors in neurons and glial cells in the brain. Specifically, research suggests vitamin D may act on particular regions of the brain important in the development of depression, including the prefrontal cortex, hippocampus, cingulate gyrus, thalamus, hypothalamus, and substantia nigra. Moreover, it has also been discovered that genetic variations of vitamin D receptors are associated with depression. Recent research shows vitamin D controls the transcription of over one thousand genes involved in neurotrophic and neuroprotective effects, including the maintenance and development of neurons. In addition, vitamin D may also stimulate the release of neurotrophins, a family of proteins that function to protect and stimulate the growth of neurons.

In a recent study, Polak et al. investigated the association between vitamin D levels and depressive symptoms in 615 young adults. Subjects in the lowest quartile of vitamin D levels were more likely to report having symptoms of depression than those in the highest quartile, suggesting that vitamin D deficiency is a potential predictor of depression. Similarly, in a study on previously deployed military personnel who committed suicide, Umhau et al. found that subjects in the lowest octile of vitamin D levels had the highest risk of suicide. Milaneschi et al. found a comparable effect in the elderly population, with low levels of vitamin D correlating with a significantly higher risk of developing depression. In another study with adolescent participants, Toppanen et al. measured vitamin D levels and depressive symptoms in the same group of children at 9.8, 10.6, and 13.8 years old. Interestingly, higher levels of vitamin D at age 9.8 predicted lower levels of depression at age 13.8, suggesting an association between low levels of vitamin D and early onset depression.

Bertone-Johnson et al., performed a cross-sectional study on 81,189 older women and found an inverse association between vitamin D levels and depressive symptoms in the postmenopausal women. In another study, Lee et al. found that lower vitamin D levels were associated with depression in a population of 3,369 European men. A study by Black et al. came to the same results in a population of young adult males.

Vitamin D supplements have also been found to enhance positive moods. In a study by Allen et al., healthy subjects were given 800 IU, 400 IU, or no vitamin D during five days of winter. The results of their study showed that vitamin D was able to significantly enhance positive affect and also reduce negative affect. Taken together, these diverse studies suggest an indisputable connection between vitamin D deficiency and depression across all age groups and genders.

Biochemical individuality plays a substantial role in vitamin D status. Although environmental factors, such as nutrition and sun exposure, are considered the major determinants of vitamin D status, genetics are responsible for a large portion of the variation seen in serum 25-hydroxyvitamin D. A Swedish study involving 204 same-sex twins between the ages of thirty-nine and eighty-five years living at northern latitude 60 degrees found that genetic factors were responsible for one-fourth of the variation in serum 25-hydroxyvitamin D, independent of season. During the summer season alone, genetics was responsible for half of the variability in 25-hydroxyvitamin D.

Vitamin D levels between 20 and 30 ng/mL have been traditionally accepted as normal and healthy. We now know that this range is too low, and even people who were thought to be safely in the middle of range may need vitamin D supplementation. Given the quirks of biochemical individuality, some people in the upper reaches may need even more. I prefer to see a 25-hydroxyvitamin D between 40 and 60 ng/mL in my patients. The best way to determine vitamin D deficiency is through serum blood testing which should also be done twice a year.

Research literature supports a link between vitamin D and depression; however, the exact mechanisms are unclear. The research has not yet established whether low levels of vitamin D cause depression, or whether depression causes low levels of vitamin D. New research is continually emerging on the importance of vitamin D in sustaining mental health. In one 2012 study, adolescents in a mental health facility who were vitamin D deficient were 3½ times more likely to have psychotic features when compared to those with sufficient vitamin D levels. We’ll explore the exciting research implicating vitamin D’s role in other mental illnesses such as psychosis and schizophrenia in the next newsletter.



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  • Lee DM, Tajar A, O’Neill TW, et al. Lower vitamin D levels are associated with depression among community-dwelling European men. J Psychopharmacol 2011 Oct;25(10):1320-8.
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  • Umhau JC, George DT, Heaney RP, et al. Low Vitamin D Status and Suicide: A Case-Control Study of Active Duty Military Service Members. PLoS One 2013;8(1):e51543.
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About the Author

James Greenblatt, M.D.

James M. Greenblatt, MD, dually board-certified psychiatrist, has treated patients since 1988 and is a pioneer of integrative medicine. He serves as the Chief Medical Officer at Walden Behavioral Care. He is the author of seven books, including Answers to AnorexiaFinally Focused, and upcoming book Functional & Integrative Medicine for Antidepressant Withdrawal. Dr. Greenblatt was inducted into the Orthomolecular Hall of Fame in 2017. He is also the founder of Psychiatry Redefined, an educational platform dedicated to the transformation of psychiatry, and Medical Director of TZ Health, a national virtual consultation clinic dedicated to the personalized, integrative treatment of mental illness.