To all governments, public health officials, doctors, and healthcare workers,
Research shows low vitamin D levels almost certainly promote COVID-19 infections, hospitalizations, and deaths. Given its safety, we call for immediate widespread increased vitamin D intakes.
Vitamin D modulates thousands of genes and many aspects of immune function, both innate and adaptive. The scientific evidence1 shows that:
- Higher vitamin D blood levels are associated with lower rates of SARS-CoV-2 infection.
- Higher D levels are associated with lower risk of a severe case (hospitalization, ICU, or death).
- Intervention studies (including RCTs) indicate that vitamin D can be a very effective treatment.
- Many papers reveal several biological mechanisms by which vitamin D influences COVID-19.
- Causal inference modeling, Hill’s criteria, the intervention studies & the biological mechanisms indicate that vitamin D’s influence on COVID-19 is very likely causal, not just correlation.
Vitamin D is well known to be essential, but most people do not get enough. Two common definitions of inadequacy are deficiency < 20 ng/ml (50 nmol/L), the target of most governmental organizations, and insufficiency < 30 ng/ml (75 nmol/L), the target of several medical societies & experts.2 Too many people have levels below these targets. Rates of vitamin D deficiency <20 ng/ml exceed 33% of the population in most of the world, and most estimates of insufficiency <30 ng/ml are well over 50% (but much higher in many countries).3 Rates are even higher in winter, and several groups have notably worse deficiency: the overweight, those with dark skin (especially far from the equator), and care home residents. These same groups face increased COVID-19 risk.
It has been shown that 3875 IU (97 mcg) daily is required for 97.5% of people to reach 20 ng/ml, and 6200 IU (155 mcg) for 30 ng/ml,4 intakes far above all national guidelines. Unfortunately, the report that set the US RDA included an admitted statistical error in which required intake was calculated to be ~10x too low.4 Numerous calls in the academic literature to raise official recommended intakes had not yet resulted in increases by the time SARS-CoV-2 arrived. Now, many papers indicate that vitamin D affects COVID-19 more strongly than most other health conditions, with increased risk at levels < 30 ng/ml (75 nmol/L) and severely greater risk < 20 ng/ml (50 nmol/L).1
Evidence to date suggests the possibility that the COVID-19 pandemic sustains itself in large part through infection of those with low vitamin D, and that deaths are concentrated largely in those with deficiency. The mere possibility that this is so should compel urgent gathering of more vitamin D data. Even without more data, the preponderance of evidence indicates that increased vitamin D would help reduce infections, hospitalizations, ICU admissions, & deaths.
Decades of safety data show that vitamin D has very low risk: Toxicity would be extremely rare with the recommendations here. The risk of insufficient levels far outweighs any risk from levels that seem to provide most of the protection against COVID-19, and this is notably different from drugs & vaccines. Vitamin D is much safer than steroids, such as dexamethasone, the most widely accepted treatment to have also demonstrated a large COVID-19 benefit. Vitamin D’s safety is more like that of face masks. There is no need to wait for further clinical trials to increase use of something so safe, especially when remedying high rates of deficiency/insufficiency should already be a priority.
Therefore, we call on all governments, doctors, and healthcare workers worldwide to immediately recommend and implement efforts appropriate to their adult populations to increase vitamin D, at least until the end of the pandemic. Specifically to:
- Recommend amounts from all sources sufficient to achieve 25(OH)D serum levels over 30 ng/ml (75 nmol/L), a widely endorsed minimum with evidence of reduced COVID-19 risk.
- Recommend to adults vitamin D intake of 4000 IU (100 mcg) daily (or at least 2000 IU) in the absence of testing. 4000 IU is widely regarded as safe.5
- Recommend that adults at increased risk of deficiency due to excess weight, dark skin, or living in care homes may need higher intakes (eg, 2x). Testing can help to avoid levels too low or high.
- Recommend that adults not already receiving the above amounts get 10,000 IU (250 mcg) daily for 2-3 weeks (or until achieving 30 ng/ml if testing), followed by the daily amount above. This practice is widely regarded as safe. The body can synthesize more than this from sunlight under the right conditions (e.g., a summer day at the beach). Also, the NAM (US) and EFSA (Europe) both label this a “No Observed Adverse Effect Level” even as a daily maintenance intake.
- Measure 25(OH)D levels of all hospitalized COVID-19 patients & treat w/ calcifediol or D3, to at least remedy insufficiency <30 ng/ml (75 nmol/L), possibly with a protocol along the lines of Castillo et al ‘20 or Rastogi et al ’20, until evidence supports a better protocol.
Many factors are known to predispose individuals to higher risk from exposure to SARS-CoV-2, such as age, being male, comorbidities, etc., but inadequate vitamin D is by far the most easily and quickly modifiable risk factor with abundant evidence to support a large beneficial effect. Vitamin D is inexpensive and has negligible risk compared to the considerable risk of COVID-19.
Please Act Immediately