As a newly minted attending fresh out of fellowship, I started my career in a less than glamorous fashion. I had been hired to launch a new satellite office in a small community hospital that was fairly limited on space. Given that I had just completed 5 years of residency and fellowship working in an underserved area with limited space and resources, I was ready for the challenge.
My first “office” was a newly renovated storage closet without windows that I shared with my office manager. We had a fantastic time nonetheless and spent three great years treating patients, learning, and laughing together along the way.
For the most part, it was a spectacular experience, however, in hindsight, I wish I had carved out 10-15 minutes each afternoon to walk outside, get some exercise, and a full dose of vitamin D. Given the long clinic hours and limited daylight, especially in winter months, it was safe to say I was living in a chronic state of Vitamin D deficiency. But how important is Vitamin D for us anyway? Let’s take a look.
What is Vitamin D?
Contrary to common belief, Vitamin D is a hormone, not a vitamin that is primarily produced in the skin upon exposure to sunlight.  It plays a number of important roles in our body that are integral for all around good health.
Why is it Important?
1) Good Bone Health:
Vitamin D is essential for the development and maintenance of healthy bones. Low levels of vitamin D have been linked to low bone density known as osteopenia, or a more severe form called osteoporosis.  Low bone density predisposes individuals to fractures of the long bones and of the spine which I see often in my practice. Unfortunately, these fractures often require surgical intervention which may have been preventable in the first place had bone health been optimized prior to the injury.
Severe Vitamin D deficiency in children can also lead to a disorder called Rickets where the bones are soft and weak. Children that develop Rickets often have stunted growth and develop spinal deformities. Fortunately, Rickets is super rare in the United States today since the introduction of foods fortified with Vitamin D in the 1940s. 
2) Boosts the Immune System:
Vitamin D can help our body fight off infection by playing an immune modulating role with B and T cells which play an integral role in combating bacteria and viruses.  Research has shown that individuals with Vitamin D deficiency have a greater susceptibility to infection. 
3) Anti-inflammatory Effects:
Vitamin D is a potent anti-inflammatory as it is believed to reduce the release of pro-inflammatory cytokines in the body. [4,6,7]
Where can you get Vit D?
You can increase your Vit D from 3 main sources-sunlight, food, and supplementation.
According to the International Osteoporosis Foundation, exposure of the face, arms and hands to sunlight for 10-15 minutes is typically sufficient in terms of meeting your daily Vit D recommendations. Obviously, this may not be a sufficient amount depending on where you live live in the world, the time of day, and your skin pigmentation. Wearing sunblock may also prevent you from reaching your daily Vitamin D goals, however, we are all well aware of the damaging effects of UV rays from this post here. Consider applying sunscreen after 10-15 minutes of soaking in some rays.
Unfortunately, food sources that contain Vitamin D are somewhat limited. They include:
Fish–Salmon, tuna, sardines
Many fortified foods including–milk, yogurs, orange juice, and cereal
According to the Institute of Food and Agricultural Sciences , the recommended dosages of Vitamin D supplementation are as follows:
*It is important to recognize that a general consensus about the exact number or recommended mcg’s of Vitamin D does not exist. These numbers will differ slightly based on the patient population being evaluated and the particular medical society that you follow.
As with all the information on this blog, it’s important to recognize that a physician should be consulted first before making any lifestyle changes, such as starting Vitamin D supplementation. It’s important to recognize that Vitamin D supplementation might now be right for everyone despite the benefits listed above.
International Osteoporosis Foundations. https://www.iofbonehealth.org/osteoporosis-musculoskeletal-disorders/osteoporosis/prevention/vitamin-d
Hewison M. Antibacterial effects of vitamin D. Nat. Rev. Endocrinol. 2011;7:337–345. doi: 10.1038/nrendo.2010.226.
Aranow, C. (2011). Vitamin D and the immune system. Journal of investigative medicine, 59 (6), 881-886.
Wang T.T., Nestel F.P., Bourdeau V., Nagai Y., Wang Q., Liao J., Tavera-Mendoza L., Lin R., Hanrahan J.W., Mader S., et al. Cutting edge: 1,25-dihydroxyvitamin D3 is a direct inducer of antimicrobial peptide gene expression. J. Immunol. 2004;173:2909–2912. doi: 10.4049/jimmunol.173.5.2909.
Helde-Frankling, M., & Björkhem-Bergman, L. (2017). Vitamin D in pain management. International journal of molecular sciences, 18(10), 2170.
US Department of Health and Human Services & US Department of Agriculture. (2015). Dietary Guidelines for Americans: 2015–2020. 8th Edition. Accessed on November 3, 2017. https://health.gov/dietaryguidelines/2015/ guidelines/appendix-12/