1. Vitamin D is not a vitamin. It is a hormone. it is structurally related to steroids and has intracellular receptors. It does not function as a cofactor in biochemical reactions like vitamins1.
2. There is a link between vitamin D deficiency and seasonal affective disorder (SAD), a form of depression which happens more often in winter months2.
3. Vitamin D is produced in the the skin (from the interaction with sunlight) and undergoes 2 modifications, one in the liver and another one in the kidney in order to achieve its full effects.
4. There are receptors for vitamin D, almost in every cellular type of the body. Intestines, bones, brain, kidneys are just examples of organs where vitamin D has an effect.
5. Darker skinned people are more vitamin D deficient than lighter skin people. Also, people living north (or south) of the 30th parallel are more deficient than those who do not.
6. There are significant associations between vitamin D deficiency and cancer, specially colorectal, breast and prostate cancers3,4,5.
7. There is an association between all-cause mortality and low levels of vitamin D6.
References
1. Vitamin D: A Hormone for All Seasons - How much is enough? Understanding the New Pressures. Morris H. The Clinical Biochemist Review. 2005; 26(1): 21–32.
2. Association Between Low Serum 25-Hydroxyvitamin D and Depression in a Large Sample of Healthy Adults: The Cooper Center Longitudinal Study. Hoang, MinhTu T. et al. Mayo Clinic Proceedings. 2011;86(11): 1050-1055
3. Association between vitamin D and risk of colorectal cancer: a systematic review of prospective studies. Ma Y, Zhang P, Wang F, et al. Journal of Clinical Oncology. 2011;29(28): 3775-3782.
4. Vitamin D Deficiency Predicts Prostate Biopsy Outcomes. Murphy AB. Clinical Cancer Research. 2014;20(9): 2289–2299.
5. Vitamin D and Reduced Risk of Breast Cancer: A Population-Based Case-Control Study. Knight JA et al. Cancer Epidemiology Biomarkers Prevention. 2007;16(3):422–429
6. Meta-analysis of All-Cause Mortality According to Serum 25-Hydroxyvitamin D. Garland CF et al. American Journal of Public Health. 2014;104(8): e43-e50.
Marco A. Ramos MD
