In the early 20th century, it was discovered that a vitamin D level of 20 ng/mL was enough to stop osteomalacia, or rickets, and this level is still used today as a marker of “sufficient” vitamin D levels. However, it’s far too low for optimal health and disease prevention beyond rickets.
- Acute respiratory tract infections
- Chronic inflammatory diseases
- Autoimmune diseases such as multiple sclerosis
Vitamin D Regulates Your Immune ResponseVitamin D receptors are present in nearly all cells of the human immune system, including monocytes/macrophages, T cells, B cells, natural killer cells and dendritic cells. Vitamin D has multiple actions on the immune system, including enhancing the production of antimicrobial peptides by immune cells, reducing damaging pro-inflammatory cytokines and promoting the expression of anti-inflammatory cytokines.9
“Receptor binding engages the formation of the ‘vitamin D3 response element’ (VDRE), regulating a large number of target genes involved in the immune response. As a consequence of this knowledge, the scientific community now agrees that calcitriol is much more than a vitamin but rather a highly effective hormone with the same level of importance to human metabolism as other steroid hormones.
The blood level ensuring the reliable effectiveness of vitamin D3 with respect to all its important functions came under discussion again, and it turned out that 40–60 ng/mL is preferable, which is considerably above the level required to prevent rickets.”
Vitamin D Is Protective Against ARDSAcute respiratory distress syndrome (ARDS) is a lung condition that’s common in severe COVID-19 cases, which causes low blood oxygen and fluid buildup in the lungs. Along with cytokine release syndrome, ARDS is one of the deadliest complications of COVID-19, and vitamin D inhibits the metabolic pathways that may cause ARDS. According to the Nutrients study:13
“Angiotensin-converting enzyme 2 (ACE2), a part of the renin-angiotensin system (RAS), serves as the major entry point for SARS-CoV-2 into cells. When SARS-CoV-2 is attached to ACE2 its expression is reduced, thus causing lung injury and pneumonia.
Vitamin D3 is a negative RAS modulator by inhibition of renin expression and stimulation of ACE2 expression. It therefore has a protective role against ARDS caused by SARS-CoV-2. Sufficient vitamin D3 levels prevent the development of ARDS by reducing the levels of angiotensin II and increasing the level of angiotensin-(1,7).”In a previous review,14 researchers also explained that vitamin D has favorable effects during both the early viraemic phase of COVID-19 as well as the later hyperinflammatory phase,15 including ARDS. “Based on many preclinical studies and observational data in humans, ARDS may be aggravated by vitamin D deficiency and tapered down by activation of the vitamin D receptor,”16 they said. “Based on a pilot study, oral calcifediol may be the most promising approach.”
- Decreases the production of Th1 cells, suppressing the progression of inflammation by reducing inflammatory cytokines produced
- Reduces the severity of the cytokine storm by promoting the differentiation of regulatory T cells
- Induces the production of antimicrobial peptide cathelicidin (LL-37), which fights respiratory viruses by disrupting viral envelopes and altering viability of host target cells
- Reduces abnormal coagulation that often occurs in critically ill COVID-19 patients
COVID-19 Mortality Drops With Higher Vitamin D LevelsThe featured study involved a meta-analysis of two data sets. One used long-term average vitamin D3 levels for 19 countries, while the other used data from 1,601 hospitalized COVID-19 patients. The hospital data included 784 patients who had their vitamin D levels measured within 24 hours of admission and 817 patients with previously known vitamin D levels.
How Much Vitamin D Do You Need?The best way to know how much vitamin D you need is to have your levels tested. It’s possible to optimize your vitamin D levels via sensible sun exposure, but if this isn’t an option for you then daily vitamin D3 supplementation of up to 10,000 units may be needed to reach a vitamin D level of 40 to 60 ng/mL.
However, if you have COVID, and you haven't been tested, it is best to take the prescription form of vitamin D called calcitriol, which is the activated form of vitamin D, as it works immediately. The dose is 0.5 mcg the first day and then 0.25 mcg for one week. This is a prescription drug. You should also take 10,000 units of regular vitamin D which will start to kick in once you are off the calcitriol.
It’s also important to note that vitamin D supplementation must be balanced with other nutrients, namely vitamin K2 (to avoid complications associated with excessive calcification in your arteries), calcium and magnesium. For another perspective, data from GrassrootsHealth's D*Action studies suggest the optimal level for health and disease prevention is between 60 ng/mL and 80 ng/mL, while the cutoff for sufficiency appears to be around 40 ng/mL. In Europe, the measurements you're looking for are 150 to 200 nmol/L and 100 nmol/L respectively.