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Should You Test Your Vitamin D Levels at Home?

vitamin d capsules

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Key Takeaways

  • Vitamin D deficiency has been linked to COVID-19.
  • More evidence is needed to learn about how not having enough vitamin D may play a factor in your risk for getting the novel coronavirus, or its severity.
  • At-home tests are on the market so people can check their levels, but some doctors think you're better off seeing a real doctor for the test.

Another recent study linked vitamin D deficiency to being at an increased risk for COVID-19, once again posing the question: Are you getting enough of the vitamin?

Vitamin D is critical for immune system function. Vitamin D supplements have been shown to reduce the risk of viral respiratory tract infections, and that may also be true for COVID-19, according to David Meltzer, MD, who led the study, published last month in JAMA Network Open.

Along with his team, Meltzer, chief of hospital medicine at UChicago Medicine, evaluated 489 patients in the hospital system who had their vitamin D levels checked within a year before COVID-19 testing. They found that those who were deficient were almost twice as likely to test positive for COVID-19 compared to those who had adequate levels in their bodies.

What Is an Adequate Level of Vitamin D?

Adults under the age of 70 are advised to get 15 mcg (or 600 IU) of vitamin D per day. If you are 71 years of age or older, 20 mcg (or 800 IU) is recommended.

Previous research has explored the potentially protective relationship between vitamin D and COVID-19. A study published in August highlighted vitamin D deficiency in COVID-19 patients who experienced acute respiratory failure. An October study on 50 COVID-19 patients linked a high dose of a type of vitamin D (calcifediol) with lower rates of intensive care unit (ICU) treatment.

Given that vitamin D is involved in many bodily functions and plays an important role in immune health, Elizabeth Shaw, RDN, a nutritionist from California, recommends getting your vitamin D levels checked.

"Vitamin D concern is something I've seen become increasingly of interest over the last three years in my practice due to the fact so many individuals across the U.S. have low vitamin D levels," Shaw tells Verywell. "As with everything, 2020 and the pandemic has definitely increased the public's interest."

Symptoms of Vitamin D deficiency include fatigue, muscle weakness, bone and joint pain, and depression.

How Can You Test Your Vitamin D Levels?

Typically, vitamin D levels are measured via routine blood work. But many Americans are delaying check-ups to maintain social distancing. An at-home test is an option to keep tabs on your vitamin D levels.

"Over the past decade, there has been an increased interest in vitamin D testing and nearly a dozen different test options are available," Stefano Guandalini, MD, a pediatric gastroenterologist at UChicago Medicine, tells Verywell. "The overwhelming majority are self-collected blood tests including at-home finger prick options like imaware."

Everlywell, Drop, and myLAB Box are other brands that offer at-home vitamin D tests. Each relies on a finger prick blood sample.

“Any at-home testing should be done by individuals who know or feel they may be at risk for low levels,” Guandalini says. These groups may include:

  • the elderly
  • people with dark skin
  • pregnant women
  • people with autoimmune conditions
  • people with gastrointestinal disorders resulting in malabsorption

“Depending on the company you purchase from, you'll experience similar [testing] practices to that of a traditional lab you would visit in-person,” she says. However, user error is always a possibility with at-home tests. If you are considering one, Shaw says to make sure you follow all protocols prior to testing.

“Appointments for walk-in blood tests are also available through laboratory locations such as LabCorp and others,” Guandalini says.

Drawbacks of At-Home Testing

“The at-home vitamin D tests seem appealing, but I would rarely encourage someone to interpret a lab result without the care of a health provider,” Melissa Majumdar, RD, a registered dietitian at Emory University Hospital Midtown in Georgia, tells Verywell. “Labs are often interpreted in the context of other labs and should not be evaluated in a silo.”

A registered dietitian can help identify the best way to take a supplement or increase food sources of the vitamin. For example, you should take vitamin D with a fat source for better absorption.

“Some providers may recommend treating a vitamin level if it is trending down, even before it is in the deficient range, or be able to relate a vitamin deficiency to a certain medication, lifestyle practice, or change in health,” Majumdar, who is also a spokesperson for the Academy of Nutrition and Dietetics, says. “These are all important conversations and cannot be included in an at-home kit."

Because so many healthcare providers are using telemedicine, Majumadar says that if you do want to use an at-home test, a follow-up telehealth appointment may be a good idea to talk through your results.

What This Means For You

Checking your vitamin D levels may be helpful, but taking vitamin D is not a prevention method for COVID-19, and it's not a cure-all for respiratory infections. Other vitamins and minerals are important for immune function, along with diet, lifestyle, sleep, and stress management.

Vitamin D and Immune Health

“While you cannot ‘boost’ your immune system, you can certainly support it with proper nutrition and supplementation when necessary,” Shaw says. “Given the research coming out surrounding COVID-19 and vitamin D levels, I would definitely encourage the public to speak with their healthcare team to figure out the supplement level that is right for them."

“To clarify, we don't want to boost immunity,” Majumdar says, explaining an optimally-functioning immune system is what people need. “‘Boosting’ implies that the immune system is on overdrive, or compensating for an outside invader.”

Martin Hewison, PhD, a professor of molecular endocrinology at the University of Birmingham, has studied vitamin D and the immune system. He tells Verywell that he doesn’t think at-home tests are worth the effort unless you are severely deficient and are at risk of bone disease.

“A key point here is that we do not know what an optimal levels of vitamin D is for combatting COVID-19,” Hewison tells Verywell.

Even if you have a measurement taken, all that a clinician can tell you is whether you are deficient or not.

“We don’t know what level of vitamin D enhances your immune function, so I don’t think that it is worth bothering with assays,” he says. “I would just suggest taking a daily supplement. I take 2,000 IU/day (50 micrograms/day) but this is purely my preference. Assume that you are likely to have low vitamin D levels during the winter and early spring and simply take a supplement.

Steven A. Abrams, MD, a pediatrics professor at the University of Texas at Austin Dell Medical School, says many people are outside less due to the pandemic, so taking a routine supplement “isn’t a bad idea.”

But taking vitamin D will not prevent or treat severe COVID-19 infection.

“That has not been shown in any substantial trials,” Abrams tells Verywell.

“The home tests are fine, although they seem like a lot of trouble compared to just taking a supplement,” he says.

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Article Sources
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  1. Meltzer DO, et al. Association of vitamin D status and other clinical characteristics with COVID-19 test resultsJAMA Netw Open. 2020. doi:10.1001/jamanetworkopen.2020.19722 

  2. National Institutes of Health Office of Dietary Supplements. Vitamin D.

  3. Carpagnano GE, et al. Vitamin D deficiency as a predictor of poor prognosis in patients with acute respiratory failure due to COVID-19. Journal of Endocrinological Investigation. 2020; doi:10.1007/s40618-020-01370-x.

  4. Castillo ME, et al. Effect of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study. The Journal of Steroid Biochemistry and Molecular Biology. 2020; doi:10.1016/j.jsbmb.2020.105751

  5. Hewison M. Vitamin D and the immune system: new perspectives on an old themeEndocrinol Metab Clin North Am. 2010. doi:10.1016/j.ecl.2010.02.010