Reasons to avoid vitamin D deficiency during COVID-19 pandemic

Abstract

The effects of vitamin D on the musculoskeletal system are well established. Its deficiency causes osteomalacia, secondary hyperparathyroidism, and an increased risk for fractures and falls. However, clinical and experimental evidence points to extra-skeletal actions of vitamin D, including on immune and respiratory systems. Thus, during this COVID-19 pandemic, a possible deleterious role of vitamin D deficiency has been questioned. This paper aims to present a brief review of the literature and discuss, based on evidence, the role of vitamin D in the lung function and in the prevention of respiratory infections. Relevant articles were searched in the databases MEDLINE/PubMed and SciELO/LILACS. The mechanisms of vitamin D action in the immune system response will be discussed. Clinical data from systematic reviews and meta-analyses show benefits in the prevention of respiratory infections and improvement of pulmonary function when vitamin D-deficient patients are supplemented. At the time of writing this paper, no published data on vitamin D supplementation for patients with COVID-19 have been found. Vitamin D supplementation is recommended during this period of social isolation to avoid any deficiency, especially in the context of bone outcomes, aiming to achieve normal values of 25(OH)D. The prevention of respiratory infections and improvement of pulmonary function are additional benefits observed when vitamin D deficiency is treated. Thus far, any protective effect of vitamin D specifically against severe COVID-19 remains unclear. We also emphasize avoiding bolus or extremely high doses of vitamin D, which can increase the risk of intoxication without evidence of benefits.

Evidences for a protective role of vitamin D in COVID-19

“…Although the degree of protection generally increases as 25(OH)D serum concentration increases, the optimal range is considered to be in the range of 40-60 ng/mL (100-150 nmol/L). In order achieve those levels, approximately half the population should take at least 2000-5000 IU/day of vitamin D. 65 The supplementation with calcidiol (25(OH)D) may present some advantages over the native vitamin D (cholecalciferol), in fact, calcidiol has a more reliable intestinal absorption (close to 100%) and its administration can rapidly restore serum concentrations of 25OHD as it does not require hepatic 25-hydroxylation (CYP27A1) (figure 1).…”

“…70 Therefore, the supplementation of vitamin D by bolus or extremely high doses (ie, 600 000 UI single dose oral dose) should be avoided since can increase the risk of intoxication without evidence of benefits at least in COVID-19 patients. 65 In addition, from the literature, for healthy individuals, it is suggested taking 10 000 IU/day for a month, which is effective in rapidly increasing serum concentrations of 25(OH)D into the optimal range of 40-60 ng/mL. 10 To maintain that level after that first month, the dose can be decreased to almost 2000-3000 IU/day.…”

“…Although the degree of protection generally increases as 25(OH)D serum concentration increases, the optimal range is considered to be in the range of 40–60 ng/mL (100–150 nmol/L). In order achieve those levels, approximately half the population should take at least 2000–5000 IU/day of vitamin D. 65 …”

“…Therefore, the supplementation of vitamin D by bolus or extremely high doses (ie, 600 000 UI single dose oral dose) should be avoided since can increase the risk of intoxication without evidence of benefits at least in COVID-19 patients. 65 …”

“…For maintenance, the dose should varies from 2000 to 3000 oral IU/day depending on the age and clinical condition of the patient up to achieve the suggested concentrations. 72 …”