Worldwide interest in the health protective benefits of vitamin D has increased exponentially since the start of the COVID-19 pandemic. We now know that low vitamin D levels are common among people of different ethnicities, geographic regions, and age groups. More importantly, low vitamin D status has a strong association with serious, chronic health conditions including infectious disease. As this is emerging research, it's easy to feel confused by conflicting scientific opinions. Here are answers to many of the key questions surrounding vitamin D.
Is Vitamin D Good for More than Healthy Bones?
Vitamin D is a fat-soluble vitamin essential to maintaining calcium balance to support bone health, muscle contraction, and cardiovascular function. Over the past 20 years, particularly during the last few years, low serum vitamin D level (the level of vitamin D circulating in blood) has been associated with many chronic health conditions, among them:
Ricketts
Bone loss leading to osteopenia or osteoporosis
Depression
Diabetes
Cancer, including breast, colon, and ovarian
Multiple sclerosis
Hypertension
Metabolic syndrome
Autoimmune conditions
Infectious disease, including respiratory tract viral infection and coronavirus
How do you test for Vitamin D Level?
Vitamin D sufficiency or deficiency is evaluated by the measurement of serum 25-hydroxyVitamin D (25-OH-D3). This is a simple, quick blood test a physician can order.
What is a 'Normal' Level for Vitamin D?
Optimal serum levels for vitamin D are a matter of debate. Different medical organizations recommend different threshold levels. For example, the Institutes of Medicine report that people with less than 25 ng/mL are deficient and 50-75 ng/mL is sufficient. The Endocrine Society, on the other hand, agrees with the 25 ng/mL for deficiency but states that levels should be higher than 75 ng/mL. Most holistic practitioners strive for a circulating level > 50 ng/mL.
When you hear "low vitamin D," that can mean either severe deficiency - a value so low that a person can develop a disease like Ricketts or suffer from bone loss. But it can also mean insufficient, which are levels that are not necessarily as high as they need to be for optimal function but not low enough to develop a disease.
Who Is Low in Vitamin D and Why?
Since 2008, research interest in vitamin D expanded from a focus on the implications of simple deficiency to looking at the role of vitamin D in the prevention of health problems. Research has revealed important findings including a detailed picture of who is most lacking in vitamin D:
Affects both the developing world and industrialized world.
Rates are higher among women than men.
50 -70 % of the European adult population.
20% or higher for non-Hispanic whites, and up to 70% for non-Hispanic Blacks.
Even in countries with plentiful sunlight year-round, levels can be below recommended levels. An example is India, a country with a prevalence rate of 50-94% vitamin D deficiency. As of May 2021, India was experiencing a high rate of infection of COVID-19. The role of vitamin D in these high rates of infection is an interesting research question.
Over the years, studies on vitamin D have focused on deficiency, rather than optimal levels for optimal function. This has changed as the association between insufficient vitamin D and chronic health conditions continues to appear in more varied and large-scale clinical studies.
Can Vitamin D Help Prevent Viral Infection?
The research is not conclusive nor final…but it is compelling. Scientists have seen in both human and animal studies that vitamin D plays an important role in immune system regulation, including how the immune system mounts a defense against viruses that invade the body. Recent studies suggest that people who are low in vitamin D have greater risk for, and worse outcomes from, respiratory infection. Vitamin D seems to up-regulate or kick into high gear the immune response around certain types of viruses. It also is being studied for its role in treatment of viral infections.
Can I Boost My Vitamin D Level, Naturally?
To boost vitamin D level naturally, experts recommend a minimum of 15-minutes, up to 30-minutes, of daily sunlight exposure without applying sunscreen. Your skin produces more vitamin D when you spend time in the sun during the middle of the day at the time the sun is at its highest point in the sky. While this type of sun exposure can elevate vitamin D levels, it is not a permanent solution for maintaining an optimal level of vitamin D throughout the year. Other factors such as weather, geography, elevation, and personal health concerns come into play.
Ultimately, the ideal level for you should be discussed with your holistic practitioner who will identify your need based on health history and lifestyle factors. Together you can decide how much sun exposure to get and/or how much and what kind of vitamin D supplementation is needed. Since vitamin D can build up to toxic levels if you take too much, it is very important to follow your doctor's guidance.
Vitamin D has garnered a great deal of attention during these past two years. As research continues and the science evolves, we will understand more about the role vitamin D plays in the immune response and protecting us from serious illness.
References
Amrein, K., Scherkl, M., Hoffmann, M. et al. Vitamin D deficiency 2.0: an update on the current status worldwide. Eur J Clin Nutr 74, 1498–1513 (2020). Retrieved 15 May 2020: https://doi.org/10.1038/s41430-020-0558-y
Palacios, Cristina, and Lilliana Gonzalez. "Is Vitamin D deficiency a major global public health problem?." The Journal of steroid biochemistry and molecular biology vol. 144 Pt A (2014): 138-45. doi:10.1016/j.jsbmb.2013.11.003 Retrieved 15 May 2020: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018438/
Interactive Map on Vitamin D Levels Worldwide: https://revista-fi.com.br/upload_arquivos/201606/2016060068176001464973585.pdf
Aparna, P et al. "Vitamin D deficiency in India." Journal of family medicine and primary care vol. 7,2 (2018): 324-330. doi:10.4103/jfmpc.jfmpc_78_18 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6060930/
"Current Vitamin D status in European and Middle East countries and strategies to prevent Vitamin D deficiency: a position statement of the European Calcified Tissue Society." European Jl Endocrinology (Apr 2019). Retrieved 15 May 2020: https://doi.org/10.1530/EJE-18-0736
The Vitamin D Society. Accessed 15 May 2021: http://www.vitamindsociety.org/videos.php?sub=Misc%20Vitamin%20D%20Videos
Holick, M.F., "Sunlight and Vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease." The American Journal of Clinical Nutrition, (1 December 2004) 80: 6,–1688S. Accessed 15 May 2021: https://doi.org/10.1093/ajcn/80.6.1678S
Grassroots Health. "Vitamin D*Action" brochure. Digital copy available: http://www.vitamindsociety.org/pdf/New%20D%20Action%20Call%20to%20action%20and%20FAQ%20sheet%20Jan%2011.pdf
NIH.gov "Vitamin D Fact Sheet for Health Professionals." Accessed 5 May 2021: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Beard, Jeremy A et al. "Vitamin D and the anti-viral state." Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology vol. 50,3 (2011): 194-200. doi:10.1016/j.jcv.2010.12.006 Retrieved 15 May 2021: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3308600/