With more than 7 million confirmed coronavirus infections worldwide, there’s a good chance COVID-19 is top of my mind for, well, everyone right now. By now we’re all intimately familiar with prevention basics. We all know to wear a mask and wash our hands for 20 seconds with soap and warm water. However, there’s still a lot we don’t know. Take the association between vitamin D status and COVID-19 risk, for example. Some experts believe the two are closely related, but is there sufficient evidence to back it up? Read on for a look at the latest science on vitamin D and the coronavirus.
First things first, why is vitamin D important for health?
Where to even start? Vitamin D, which actually acts as a hormone (not a vitamin) performs countless functions in the body. The critical nutrient aids in calcium and phosphorous absorption, which helps keep bones strong. It also serves as an anti-inflammatory and immunoregulatory hormone. Low levels of vitamin D are associated with increased risk of chronic diseases like breast and prostate cancers, heart disease, and type 2 diabetes.
What does the science say about vitamin D and COVID-19?
It’s too early to make any sweeping conclusions about vitamin D and coronavirus risk. That’s because we need large scale randomized clinical trials in order to collect the kind of data that demonstrates causation (for example: vitamin D supplementation leads to improved COVID-19 outcomes).
The pandemic’s death toll and economic impact have been devastating. Scientists are working overtime to assess the relationship between vitamin D and the coronavirus. So, what have they found?
So far, research suggests individuals with low vitamin D levels may be more likely to be infected with COVID-19. One May 2020 study published in the journal Aging Clinical and Experimental Research compared mean vitamin D levels and the number of cases and deaths of COVID-19 in various European countries. The researchers found that the lower the average vitamin D status of the population, the higher the number of COVID-19 infections and deaths, and vice versa.
Another study published in the journal Nutrients last month noted that because higher levels of vitamin D have been associated with a decreased risk of respiratory infections (like those that follow from the flu and pneumonia), vitamin D3 supplementation may help prevent or decrease the severity of COVID-19 in individuals with low vitamin D levels.
There’s also the thought that the coronavirus outbreak began in the winter, which is when peoples’ vitamin D levels tend to be lower. That’s because sun exposure transforms a type of cholesterol in the skin into active vitamin D in the body — and most of us don’t sunbathe in single digit temps.
One more thing: Black and elderly individuals are two groups that are among the most at risk for severe COVID-19 outcomes. They’re also two groups that are more likely to have a vitamin D deficiency.
People with darker skin tend to have lower levels of vitamin D because melanin decreases the amount of vitamin D that’s produced in the body in response to sun exposure. Let’s not forget that Black people and POC are also unjustly subject to greater health disparities and neglect by healthcare providers due to the racism that’s endemic to our society’s systems, Western medicine included. What’s more, national dietary guidelines are “based on an assumption that the requirements between white and other ethnic groups do not differ, largely due to the absence of data,” per a 2014 study published in The American Journal of Clinical Nutrition. As a result, the “normal” range used by providers to assess vitamin D levels in Black individuals and POC may not even be appropriate. Nutrition research clearly has work to do in order to be more inclusive of and applicable to these groups.
In the case of older adults, vitamin D levels tend to be lower since they typically spend less time in the sun and eat fewer (or smaller amounts of) foods that contain the nutrient.
How does vitamin D influence immune health?
Ok, so there’s evidence that adequate levels of vitamin D might be protective against COVID-19. But how exactly does the nutrient influence respiratory health? Vitamin D supports immunity by decreasing the amount of pro-inflammatory cytokines in the body. Additionally, vitamin D increases the amount of T regulatory cells released by the immune system. Both of these actions help dial down the “cytokine storm” that contributes to COVID-19 complications like organ failure and stroke.
How can I add more vitamin D to my diet?
Safe sun exposure is the best way to increase vitamin D levels. Experts recommend getting about 15 minutes of sun exposure (sans sunscreen) daily to maintain healthy serum levels. Of course, this guideline may change depending on factors like your medical history, age, skin tone, and geographical location (rays are stronger in southern areas compared to northern areas).
While dietary approaches for upping your vitamin D intake are limited, they do exist. Natural sources of vitamin D include egg yolks and fatty fish (think: sardines, trout, salmon, tuna, mackerel). Most cow’s milk and dairy alternatives like soy or almond milk are fortified with vitamin D. So are some cereals, yogurts, and orange juice.
Talk to your doctor or an RD about supplementation options if you have or are at risk of a vitamin D deficiency. Older adults may require daily supplements that provide around 800 to 2000 IUs of vitamin D3.
The bottom line
Numerous studies have demonstrated an association between vitamin D and the coronavirus. This link may be due to the fact that vitamin D plays a key role in down-regulating potentially harmful cytokines and increasing the production of anti-inflammatory compounds that help the body fight infection.
Our take? For now, there isn’t sufficient evidence that vitamin D is a coronavirus cure-all or the key to prevention. Plus, loading up on any supplement can come with risks. That said, vitamin D is a critical nutrient for overall health. If your lab work shows that your vitamin D levels are low, we recommend making a point to eat more vitamin D-rich foods and adding a supplement to your daily regimen, with guidance from your doctor or dietitian.
When it comes to vitamin D and the coronavirus, remember this: our bodies are extremely complex. No single supplement (or ingredient or food or powder) is a magic bullet for health. If only it were that simple.