Vitamin D Supplementation: A Potential Approach for COVID-19 Therapeutics

Vitamin D is likely to reduce acute respiratory tract infection risk, and that 10,000 IU/day is safe.
It is not considered possible to achieve toxic levels via the sun alone, and supplementation for prolonged periods brings 25(OH)D to toxic levels only if the dose is consistently extraordinarily high (40,000 IU/day for many months) (28, 88, 91, 92). The average naturally acquired 25(OH)D among equatorial tribal groups is 46 ng/ml (93). Healthy lifeguards typically have 25(OH)D levels of 100–125 ng/ml (29).
The Endocrine Society found toxicity symptoms only at levels above 150 ng/ml (93).
Heaney et al., supported the higher level in a reply, citing a recent supplementation study which supported an RDA closer to 7,000 IU/day (97).
Parathyroid hormone levels were not reduced in participants taking 15,000 IU/day, even with 25(OH)D levels above 60 ng/dl, in a study with a goal of bringing 25(OH)D levels up to at least 40 ng/dl (93).
25(OH)D levels of up to 120 ng/dl appeared safe, and hypercalcemia and hypercalciuria were least common in participants with the highest 25(OH)D levels (calcium was not supplemented) (93).
Goal 25(OH)D levels were achieved by 70% of the participants with 6,000 IU/day for normal weight participants, but 7,000 and 8,000 IU was required for overweight and obese participants, respectively (93).
Growing research suggests that 40–60 ng/ml is needed for prevention of respiratory infections, and 50–80 ng/ml is required to favorably influence hypertension and cardiovascular disease (28).
Mean 25(OH)D levels in the 400 IU/day group did not increase, while 25(OH)D for the 10,000 and 4,000 IU/day groups rose and then plateaued at 58 and 53 ng/dl, respectively (98).
The Endocrine Society recommends up to 10,000 IU/day, particularly for obese individuals (93, 99). However, some study participants have taken 15,000 to 40,000 IU daily for at least 6 months without apparent adverse effects (91).
Grant et al. authored an early article positing a relationship between COVID-19 and vitamin D which recommended 10,000 IU/day for 1 month, followed by 5,000 IU/day, with a goal 25(OH)D of 40–60 ng/ml (19).
Sharma et al., reviewed the literature informing decisions about COVID-19 and vitamin D₃, finding compelling evidence for 10,000 IU/day for a month, followed by 5,000 IU/day to bring 25(OH)D levels up to the target of 40–60 ng/ml, then recommended a more modest 1000–2,000 IU/day (107).

~Praveen Jada

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