Several of these studies connected vitamin D deficiency and insufficiency not only with COVID infection, but also with an increase in hospitalization, ICU admission, mortality, and reinfection rate of COVID-19
Since early in the pandemic, health experts have warned that people with certain medical conditions have a greater risk of developing a severe initial case or reinfection rate of COVID-19. The Centers for Disease Control and Prevention shares that this includes those with cancer; chronic kidney, liver, or lung disease; diabetes; heart disease; and more.
Yet, newly published research indicates that there’s another factor that may make patients a bigger COVID target, and that is low levels of vitamin D.
Vitamin D levels and risk of COVID-19
On July 2, 2021, the Cardiology Journal published a systematic review and meta-analysis which looked at whether a person’s vitamin D levels impacted whether they were at risk of contracting COVID-19. It included 13 studies with a total of 14,485 participants, all of whom were over the age of 18.
After analyzing the data, researchers noted that individuals testing negative for SARS-Co-V-2 had mean vitamin D levels of 17.7 ng/mL. However, the mean vitamin D levels for those testing positive was more than three points lower, or 14.1 ng/mL. Thus, the researchers concluded that “low serum vitamin D levels are statistically associated with the risk of COVID-19.”
Low vitamin D and COVID severity
An even larger review was published on December 22, 2021, by Frontiers in Public Health. This piece of research sought to discover whether a connection exists between low vitamin D levels and COVID severity.
In this review, 54 studies were included with a total of 1,403,715 subjects. It found that several of these studies connected vitamin D deficiency and insufficiency not only with COVID infection, but also with an increase in hospitalization, ICU admission, mortality, and reinfection rate of COVID-19.
The vitamin D-COVID connection and reinfection rate of COVID-19
How is it that low vitamin D levels can potentially make a patient more susceptible to COVID?
In an article published by Clinical Medicine (London), researchers suggest that one possible explanation is that T regulatory lymphocytes (Tregs) help protect against viral infection and vitamin D supplementation can increase Treg levels. Additionally, low vitamin D is also associated with an increased risk of pneumonia, viral upper respiratory tract infection, and thrombotic episodes — all of which are frequently observed with those who have COVID-19 and with the reinfection rate of COVID-19.
Another systematic review and meta-analysis, this one including 14 studies and published in Frontiers in Public Health, explains that vitamin D helps reduce the risk of infection and death by modulating both innate and adaptive immunity. This provides an antiviral and anti-inflammatory effect. It also enhances the expression of ACE-2 (Angiotensin-converting enzyme 2), which mediates COVID’s development.
Increasing vitamin D levels in patients
Studies such as these suggest that increasing patients’ vitamin D levels may help not only reduce their risk of contracting COVID-19 in the first place but might also reduce its severity if they are infected.
The National Institutes of Health (NIH) recommends that most children and adults consume 15 mcg of vitamin D daily. Individuals over the age of 70 need slightly more, or closer to 20 mcg per day. Children under the age of 12 months need slightly less, or 10 mcg per day.
Not a lot of foods naturally contain this vitamin. Fatty fish and fish liver oils are the best choices with beef liver, egg yolks, and cheese providing smaller amounts. Mushrooms treated with UV lights are also considered good sources of vitamin D, as are foods that are fortified, which includes milk, milk alternatives, and cheese.
Spending time in the sun can also increase vitamin D in the body. The NIH indicates that the guidelines for sun exposure vary, with some researchers suggesting that it’s optimal to spend between five and 30 minutes in the sun per day (or at least twice weekly), preferably between the hours of 10 a.m. and 4 p.m. However, it’s also important to not overdo it as too much sun can increase skin cancer risk.
Supplementation is another option for boosting vitamin D levels. Both multivitamins and stand-alone vitamin D supplements can help increase a patient’s vitamin D intake. While more research needs to be conducted to understand the connection more clearly, it appears that taking this one step might provide some protection against getting COVID-19 and the reinfection rate of COVID-19, or to reduce its severity if this virus is contracted.
