Dev Mishra, M.D.
President, Sideline Sports Doc
Medical Director, Apeiron Life
Fellow, American Academy of Orthopaedic Surgeons
Center For Joint Restoration, Menlo Park, CA
September 1, 2020
- Recently published scientific studies suggest that a low Vitamin D level increases risk of contracting Covid-19
- Taking simple steps to increase Vitamin D is safe through modest sunlight exposure, increasing food sources in your diet (cold water fish), and taking a Vitamin D supplement
- Combining mask use, physical distance, and Vitamin D could be an effective combination to reduce virus risk
This week I’ll highlight two interesting studies linking low Vitamin D levels to increased Covid-19 risk. Both of these studies suggest that low Vitamin D levels are independent risk factors for Covid-19 risk, meaning that there is something about the low Vitamin D level in the body that leads to the increased risk, without other contributing factors.
In my experience, a surprising number of adults have low Vitamin D levels. Given that it’s so easy to increase your Vitamin D level either through a modest increase in sunlight exposure, proper food sources, or through supplementation, this represents an easily controllable way to reduce risk of Covid-19.
What Is Vitamin D
Vitamin D is a fat soluble vitamin that is produced in the skin when the skin is exposed to ultraviolet sunlight. There are many functions of Vitamin D in the body, and there is good scientific evidence to support the following:
- Improves bone health
- Improves immune function
- Decreases risk of autoimmune diseases
- Decreases risk of cancer
- Decreases risk of heart disease
- Decreases risk of premature death
- Regulates hormones
Vitamin D and Covid-19 Risk
Let’s have a look at two recently published scientific studies linking low Vitamin D to increased risk of Covid-19.
First, a University of Chicago Medicine study examined the electronic medical records of 4,314 individuals tested for COVID-19 between March 3 and April 10, 2020. Blood tests for vitamin D levels within the previous two years were used to assess vitamin D insufficiency. The retrospective design of the study limits its strength but there are some important takeaways.
18% of the Vitamin D deficient individuals tested positive for Covid-19, compared to 11% positivie in the normal Vitamin D group. This is interesting but does not prove that the low Vitamin D directly led to the increase positive test rate.
And that’s what the second study attempted to show. This study included 14,000 members of Israel’s Leumit Health Services who were tested for COVID-19 between February 1 and April 30, 2020; 7,807 had recent vitamin D tests.
Without digging too deep into the details of the study design, I’ll just say that it was a more rigorous design and does show plausible cause-and-effect. A low vitamin D level was correlated with a 1.5X increased risk of testing positive for COVID-19 and almost 2X the increased risk of hospitalization from the disease. The only risk factor that was more relevant than vitamin D level was being older than 50 – which resulted in 2.7X greater risk of hospitalization.
What To Do
To be clear, taking Vitamin D will not prevent you from getting the Covid-19 virus, but combined with other proven strategies such as using a mask and maintaining physical distance it could reduce your risk.
It’s easy to get your Vitamin D level tested. Several companies now offer at-home test kits requiring only a few drops of blood. Or, you could simply take reasonable action such as making sure you have adequate sun exposure. The key sources of Vitamin D in the body are sun exposure, food sources, and supplements. I’ve written previously about ways to increase Vitamin D, here are the key points:
- Get 15-20 minutes of sun exposure, 3 times per week. Use sunscreen, and don’t overdo your sun exposure
- Use a standard daily multivitamin supplement which contains Vitamin D
- Cold water fatty fish will also help your Vitamin D levels
Overall, this is such a simple step to take and one that will not only have the potential to reduce your chance of contracting the Covid-19 virus, but will also have multiple positive effects in your body.