Vitamin D lowers the risk of life-threatening COVID-19 infections and ICU admission

Ever since the COVID-19 pandemic started, scientists have focused on vitamin D. This nutrient strengthens and regulates the immune defense in a number of different ways. Numerous studies have shown that lack of vitamin D increases the risk of being infected with COVID-19 and running into complications. High-dosed vitamin D supplementation of COVID-19 patients can lower their risk of being admitted to the intensive care unit and dying of the disease, according to a new meta-analysis that is published in Nutrients.

COVID-19 is caused by an RNA virus (SARS-CoV-2). Just like other types of coronaviruses, COVID-19 is extremely prone to mutations. Most people who are infected only develop light flu-like symptoms or no symptoms at all. However, according to WHO, the disease has a death toll of over seven million until now (2024).
When the body is infected with the virus, the immune system normally destroys virus particles that have attached to the respiratory mucosa and form some kind of immunity. If the immune system does not function optimally, however, the virus moves on to the lower respiratory tract. In rare cases, acute respiratory distress syndrome (ARDS) develops, and this may result in septic shock. The condition is a result of the immune defense overreacting with hyperinflammation that causes damage to the pulmonary epithelial cells. Hyperinflammation and damage can also arise in the blood vessels, causing circulatory failure and eventually death.
It is typically in older and chronically ill people and other vulnerable groups that COVID-19 leads to ARDS, and this is associated with ICU admission and an increased risk of dying of the disease. It has been observed that vitamin D deficiency is far more widespread among these individuals.
Multiple studies have looked at the effect of giving vitamin D supplements to COVID-19 patients, but it has never been standard therapy. In the new meta-analysis, the scientists wanted to investigate the relation between vitamin D supplementation and the severity of COVID-19 in hospitalized patients. The review included a total of 13 randomized, clinical tests that looked at:

• The number of hospitalizations due to COVID-19 infections
• The duration of ICU stays
• The need for and duration of ventilator therapy
• The total length of hospital stays
• COVID-19-related mortality
• Total mortality

The meta-analysis showed the following:

• Supplementation with vitamin D lowered the risk of being admitted to ICU.
• Supplementation with vitamin D lowered COVID-19 mortality.

According to the meta-analysis, vitamin D supplementation did not affect the length of hospital stay, but studies have shown conflicting results. In any case, vitamin D should be administered in quantities that are sufficiently high to rapidly optimize blood levels of the nutrient.
The scientists behind the new meta-analysis conclude that vitamin D generally lowers the risk of being admitted to ICU and dying of COVID-19. They also refer to a study where a combination of vitamin D, magnesium, and vitamin B12 given to older COVID-19-infected patients lowered their risk of ICU admission. This combination of nutrients is highly relevant because magnesium helps activate vitamin D. Also, vitamin B12, which many older people lack, helps reduce the production of pro-inflammatory proteins like CRP (C-reactive protein).

How does vitamin D counteract COVID-19 infections and complications?

Vitamin D strengthens the epithelial cells that are natural barriers in our airways, blood vessels, and other places. The vitamin also strengthens our innate immune defense, including the macrophages and certain antibiotic compounds in the airways that are able to tackle most germs without developing symptoms.
Vitamin D is also important for the adaptive immune defense and for activating T cells that give us optimal immunity in connection with virus infections. Last but not least, vitamin D regulates the inflammatory processes, which is a highly important function because COVID-19 complications are a result of uncontrolled hyperinflammation.

• An estimated one billion people worldwide lack vitamin D.
• The official recommendations (5-20 micrograms/day) for vitamin D are too low to optimize blood levels of the nutrient
• People with dark skin, older people, overweight individuals, and diabetics have difficulty with synthesizing vitamin D from sunlight or activating the vitamin
• The need for supplementation varies from person to person. Supplements available that contain between 20 and 100 micrograms of vitamin D

References:

Marharyta Sobczak and Rafal Pawliczak. Effect of Vitamin D Supplementation on Severe COVID-19: A meta-Analysis of Randomized Clinical Trials. Nutrients 2024

Fausto Petrelli et al. Vitamin D3 and COVID-19 Outcomes: An Umbrella Review of Systematic Reviews and Meta-analysis. Antioxidants 2023

Constanza Gavioli et al. Vitamin D and SARS-CoV-2 Infection, Severity and Mortality: A systematic Review and Meta-Analysis. PLOS ONE. July 6, 2022

Max Schmeling, Vibeke Manniche, Peter Riis Hansen. Batch-dependent safety of the BNT162b2 mRNA COVID-19 vaccine. European Journal of Clinical Investigation 2023