A number of recent studies have suggested that having optimal levels of Vitamin D could help decrease the severity of COVID-19 if you become infected. It seems that patients from countries with high COVID-19 mortality rates, such as Italy, Spain, and the UK, had lower levels of Vitamin D. In fact, a preliminary study found that patients under 75 years of age who contracted COVID-19 and ended up needing care in the ICU were all deficient in Vitamin D.
This is partly because vitamin D helps avoid or decreases the severity of a cytokine storm. A cytokine storm is when your immune system starts to betray you by overreacting to the virus. The immune system produces and releases large amounts of pro-inflammatory cytokines and chemokines which leads to a systemic inflammatory response, followed by the immune system “attacking” the body. Vitamin D enhances cellular immunity by reducing this cytokine storm. It can help reduce the production of pro-inflammatory Th1 cytokines and increases the expression of anti-inflammatory cytokines.
While we don’t have enough information yet on Vitamin D’s role in prevention, the evidence currently available on the severity of COVID-19 if you become infected seems to be clear that it may help decrease the risk of COVID-19 infection and death.
Five facts about Vitamin D
1) Contrary to its name, vitamin D is a hormone, not a vitamin. It has a chemical structure of a steroid hormone and is similar to hormones produced by our adrenal glands, ovaries, or testes.
2) Vitamin D may decrease the risk of some types of cancers. There are quite a few studies available on Vitamin D status in relation to cancer risk. The majority found that sufficient Vitamin D levels lower the risk of cancers, including colon, breast, prostate, and ovarian.
3) Vitamin D deficiency increases the risk of cardiovascular disease, including hypertension, heart failure, and heart attack.
4) Vitamin D helps support memory and cognition. Receptors for vitamin D are found throughout the brain and play an important role in making memories. Low vitamin D levels are associated with an increased risk of dementia, difficulty remembering general information and managing thinking processes. Omega 3 and Vitamin D also helps the body make more of your feel-good hormone, serotonin, which is very important in this stressful time.
5) Vitamin D improves blood sugar regulation and insulin sensitivity. Decreased vitamin D levels were associated with an increased risk of diabetes and insulin resistance. That’s because vitamin D helps regulate insulin production and release thus facilitating glucose uptake. Some evidence even suggests that getting enough Vitamin D could enhance weight loss and decrease body fat. One study found that women who are overweight and received a Vitamin D supplement lost an average of 7 pounds more than women who did not.
To maintain healthy blood levels, aim to get 10–30 minutes of midday sunlight, several times per week. Your exposure time should depend on how sensitive your skin is to sunlight. Many factors can affect your ability to get sufficient amounts of vitamin D through the sun alone.
These factors include:
- Using sunscreen
- Being in an area with high pollution
- Living in big cities where buildings block sunlight
- Having darker skin reduces vitamin D creation due to high melanin (skin pigment).
- Spending more time indoors
A vitamin D deficiency may present these symptoms:
- aches and pains, fatigue and a general sense of not feeling well
- severe bone or muscle pain or weakness that may cause difficulty climbing stairs or getting up from the floor or a low chair, or cause you to walk with a waddling gait
- stress fractures, especially in your legs, pelvis, and hips
Doctors can diagnose a vitamin D deficiency by performing a simple blood test. If you’re diagnosed with a vitamin D deficiency, your doctor will likely recommend you take daily vitamin D supplements. If you have a severe deficiency, they may instead recommend high-dose vitamin D tablets or liquids. Consult your doctor for a recommendation that suits your needs.
Foods that are high in Vitamin D
It is important to remember that you can get vitamin D through the foods you eat. Only a few foods contain Vitamin D naturally. These include the following:
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FoodData Central. “Fish oil, cod liver”. Published April 2019. Accessed May 2020.
FoodData Central. “Fish, sardine, Atlantic, canned in oil, drained solids with bone”. Published April 2019. Accessed May 2020
Garland C., et al. “The role of Vitamin D in cancer prevention”. Am J Public Health. 2006: 96(2): 252-261.
Grant W., Lahore H., McDonnell S., Baggerly C., French C., Aliano J., Bhattoa H. “Evidence that vitamin d supplementation could reduce risk of influenza and COVID-19 infections and deaths." Nutrients. 2020: 12(4): 988.
Kuhn J. et al. ”Free-range farming: a natural alternative to produce vitamin D-enriched eggs”. Nutrition. 2014: 30(4): 481-484
Lau F. Majumder R., Torabi R., Saeg R., Saeg F., Hoffman R., Cirillo J., Greiffenstein P. “Vitamin D insufficiency is prevalent in severe COVID-19”. Preliminary Study.
Lu Z., et al. “An evaluation of the vitamin D3 content in fish: is the vitamin D content adequate to satisfy the dietary requirements for Vitamin D?” J Steroid Biochem Mol Miol. 2007: 103(3-5): 642-644.
Mason C. et al. “Vitamin D3 supplementation during weight loss: double-blind randomized controlled trial”. Am J Clin Nutr. 2014: 99(5): 1015:1025.
Miller J. et al. “Vitamin D status and rates of cognitive decline in a multiethnic cohort of older adults”. JAMA Neurol. 2015: 72(11): 1295-1303.
Peterson C., Tosh A., Belenchia A. “Vitamin D insufficiency and insulin resistance in obese adolescents”. Ther Adv Endocrinol Metab. 2014: 5(6): 166-189.