While we are focused on the COVID pandemic, another pandemic is lurking in the shadows and contributes to the frequency and severity of chronic disease around the planet.  I am talking about deficiency in Vitamin D and it is on the rise, particularly amongst those residing in Northern latitudes, with darker skin and amongst our aging populations. Low levels of Vitamin D have been linked to a diversity of adverse health outcomes and chronic diseases including cancer, diabetes, osteoporosis, heart disease, metabolic syndrome, depression, inflammation, and lowered immunity.  Deficiency in Vitamin D has even been linked to severity of COVID-19.

What is Vitamin D?

You may have heard of Vitamin D in the prevention of rickets, but did you know that it has many other purposes in the body? Vitamin D is a fat-soluble prohormone (meaning it can turn into a hormone) that comes in two known forms – D2 or D3. Both forms are converted to 25-hydroxyvitamin D in the liver and then again to its active form 1,25-dihydroxyvitamin D, or calcitriol, in the kidneys.  It is then used by the body to strengthen bones through aiding the absorption of calcium and phosphorus, help regulate circadian rhythms and sleep, modulate immune responses to infections, protect from inflammatory damage, and halt or slow disease progression.

Where can you get Vitamin D?

Unfortunately, dietary sources of Vitamin D are scarce so we will have to look beyond the plate.  Foods like milk, cereal and orange juice are often fortified to reach the RDA of 600 IU for adults and children ages 1-70 years old and 800 IU daily for adults 71+. Other sources include fatty fish like wild salmon, mackerel or sardines, and egg yolks. Mushrooms like shiitakes, exposed to sunlight can also inherently produce Vitamin D.  However, most of our Vitamin D comes from ultraviolet-B (UVB) radiation from sunlight.

It is suggested that exposure of bare arms and legs to midday sun (between 10am and 3pm) for 5-30 minutes twice a week may be sufficient to achieve these requirements. However, the amount of Vitamin D one produces is influenced by latitude, season, time of day and time of year, skin color, age, amount of skin exposed, and sunscreen use. For instance, those with darker skin produce more melanin – which competes with the absorption of UV light and reduce Vitamin D production. So darker skinned folks may need up to ten times more sun exposure than those with fair skin.


Besides Vitamin D benefits, regular sunlight exposure can also boost your mood, so it is good to get out for at least 10-15 minutes a day.



Can I supplement?

For those who cannot reach their Vitamin D goals, supplementation is a good idea. How much to take is under debate, but the best place to start is to get your Vitamin D levels tested with a simple blood test.  The optimal functional level is between 50-70 ng/mL. Some functional doctors like to see levels even higher. To determine the right dose, it is best to work with a practitioner to make sure you get the right amount and the right type.

Vitamin D may also interfere with some medications like Lipitor, Dovonex, Steroids, or those containing aluminum to mention a few. Talk to your doctor before beginning any new supplement if you are on medication.


What about COVID-19?

New research suggests that Vitamin D levels of at least 40-60 ng/mL can lower your risk for seasonal influenza and COVID-19. Given Vitamin D’s role in cardiovascular diseases and diabetes mellitus prevention and its involvement in pulmonary ACE2 expression as well as immune cell activity and reduced concentrations of IL-6 (a major inflammatory marker we see in infections of this sort), it has been suggested that Vitamin D would be a useful addition to both therapy and prevention for COVID-19.

Berk et al (2013). So depression is an inflammatory disease, but where does the inflammation come from? BMC Medicine (11):200. http://www.biomedcentral.com/1741-7015/11/200
Ebadi, M., & Montano-Loza, A. J. (2020). Perspective: improving vitamin D status in the management of COVID-19. European journal of clinical nutrition74(6), 856–859. https://doi.org/10.1038/s41430-020-0661-0
Grant, W. B., Lahore, H., McDonnell, S. L., Baggerly, C. A., French, C. B., Aliano, J. L., & Bhattoa, H. P. (2020). Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients12(4), 988. https://doi.org/10.3390/nu12040988
Laird, E., Rhodes, J., & Kenny, R. A. (2020). Vitamin D and Inflammation: Potential Implications for Severity of Covid-19. Irish medical journal113(5), 81.
National Cancer Institute. (2013, Oct.21). Vitamin D and Cancer Prevention .Retrieved from: http://www.cancer.gov/cancertopics/causes-prevention/risk-factors/diet/vitamin-d-fact-sheet
Urashima, M., Segawa, T., Okazaki, M., Kurihara, M., Wada, Y., & Ida, H. (2010). Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. The American journal of clinical nutrition91(5), 1255–1260. https://doi.org/10.3945/ajcn.2009.29094
Additional Resources: