We know that Vitamin D is good for our bones – but can it also help against COVID-19? Here’s what the experts say.

You may have noticed the many headlines circulating these days questioning whether there is a connection between vitamin D deficiency and COVID-19 outcomes. For years, health researchers have studied the role vitamin D plays in guarding against the severity of acute respiratory illnesses, and they’ve found that vitamin D deficiency has accounted for a significant number of deaths in older patients with respiratory disease1. The link between vitamin D and general immunity function has been studied as well2, and it is suggested based on this research that people who are deficient are more prone to both bacterial and viral infections.

Vitamin D is a fat-soluble nutrient that regulates the absorption of calcium and phosphorus vital to keeping our bones, teeth, and immune system strong3. There are three ways we can obtain vitamin D. Vitamin D is produced in the body when our skin is directly exposed to ultraviolet rays from sunlight. Vitamin D is also available as a dietary supplement. Lastly, some foods naturally contain vitamin D, such as fatty fish like salmon and tuna, and fish liver oil, cheese, and egg yolks. Other foods are fortified with vitamin D, such as commercially available milk, ice cream, orange juice, yogurt, and breakfast cereals.

Vitamin D deficiency is achieved when intake is lower than the recommended amount over time, when exposure to the sun is limited, or when absorption of vitamin D in the body is restricted. Diets that restrict or eliminate animal or dairy products, such as vegetarian and vegan diets, are associated with deficiency as well. Certain groups are more susceptible to vitamin D deficiency, including people who are older, who have darker skin, who are obese, and who have certain medical conditions. When deficiency is detected, supplementation is suggested to restore healthy levels.  According to the National Institutes of Health, the recommended dietary allowances for vitamin D are:

  • 0-12 months      400 IU
  • 1-18 years          600 IU
  • 19-70 years       600 IU
  • > 70 years         800 IU

Awareness surrounding vitamin D’s important role in helping determine respiratory illness and immune function outcomes has led scientists worldwide to most recently study the possibility of whether supplementing vitamin D can prevent or reduce the severity of COVID-19 symptoms. These studies show that people who are vitamin D deficient are indeed significantly more likely to suffer higher rates of COVID-19 infection and death. This was especially seen in Europe4.  Southern European countries like Spain had Italy, where locals generally have darker skin, were hit harder than northern European countries, where people tend to consume more vitamin D supplements.

While these studies are promising in that they suggest an association between vitamin D and COVID-19 prevention, there still is not enough evidence to show causation between the two. Many open questions still remain: does a deficiency really cause increased susceptibility, or does it merely reflect it? Could other factors be causing the deficiency, such as age, chronic illness, smoking habits, spending time indoors, or using sunscreen regularly?  These and other variables were not always accounted for when vitamin D and COVID-19 were studied. This means that while there may be a connection, we cannot yet conclude that taking vitamin D will help prevent COVID-19.

When it comes to boosting vitamin D levels, it is important to be aware of the risks of overdosing. Vitamin D toxicity is typically caused by taking large doses of supplements for several months, leading to a buildup of calcium in the blood. Symptoms of toxicity include vomiting and nausea, frequent urination, and weakness, and can lead to kidney conditions and bone pain if not treated5. Always discuss any concerns you have about your vitamin D level with your doctor to receive the proper guidance on dosing.

So what’s the bottom line? Don’t rush to take more vitamin D just yet, as more research is needed. There are still many unknowns, and a variety of different types of studies are still necessary to confirm whether a link truly exists between vitamin D and the prevention of COVID-19. For now, your best bet is to keep practicing all of the usual safety protocols such as social distancing, wearing masks, and washing your hands to help keep COVID-19 at bay.

Sources:

1) Martineau Adrian R, Jolliffe David A, HooperRichard L, Greenberg Lauren, Aloia John F, Bergman Peter et al. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ.356 :i6583.

2) Hewison, Martin. (2011). Vitamin D and immune function: An overview. The Proceedings of the Nutrition Society. 71. 50-61.

3) https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

4) Ilie, P.C., Stefanescu, S. & Smith, L. (2020). The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality. Aging Clinical and Experimental Research. 32. 1195–1198.

5) https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/vitamin-d-toxicity/faq-20058108