Everything we need to know about vitamin D

The role of vitamin D in women’s health and in patients with COVID-19 were reviewed and assessed by Dr Santiago Palacios, gynecologist and menopause research expert (Madrid) and Dr José López Miranda, professor and head of the Internal Medicine Unit of the Reina Sofía Hospital (Córdoba). This was reviewed during a webinar, moderated by Dr Fernando Losa, obstetrician gynecologist, maternologist, obstetrician and menopause expert (Barcelona)

According to Dr. Palacios, in recent years the relation between the prevention of falls and fractures with vitamin D supplementation has been demonstrated1,2 . But on the other side, 25(OH)D levels have been correlated with parathyroid hormone (PTH) levels and bone mineral density (BMD)3 . Therefore, current recommendations support favourable vitamin D supplementation in any osteoporosis prevention plan. A dose of 800 to 1,200 Ul/day is generally recommended

In addition, vitamin D supplementation can also prevent sarcopenia, as it has a close relationship with muscle. Vitamin D binds to the vitamin D receptor on muscle fibres and increases their size. Consequently, this improvesimproving muscle strength and physical performance. The progressive loss of vitamin D receptors during ageing causes a loss of muscle mass and strength, which correlates with an increased risk of falls and fractures

In the field of Gynecology, vitamin D levels can influence various pathologies during adolescence (menarche, developmental disorders, gynaecological infections), as well as during the fertile period or in polycystic ovary syndrome. In addition, vitamin D deficiency in pregnancy can have consequences for both the mother (pre-eclampsia, gestational diabetes, premature birth, recurrent miscarriage, postpartum depression) and the foetus (low birth weight, respiratory tract infections, asthma, low immunity, autism).

Therefore, prophylactic administration of vitamin D may be indicated in many situations to improve women’s health. In these cases, dosage should be individualised and based on doses dependent on 25(OH)D concentration, the patient’s age, body weight and lifestyle.

Dr López Miranda focused on the current COVID-19 pandemic and the effects of acute respiratory distress syndrome (ARDS) triggered by SARS-CoV-2. COVID-19 is characterised by lung inflammation, thick mucus secretions in the airways, elevated levels of pro-inflammatory cytokines, extensive lung damage and microthrombosis.

ARDS is very difficult to treat in late stages. Currently, there is no pharmacological treatment which had shown to be effective in reversing the damage caused or reversing the natural history of the disease. Early treatment is essential to prevent infections and avoid the development of a severe systemic inflammatory response, thus improving the prognosis of ARDS patients.

According to Dr López Miranda, one of the therapeutic strategies being investigated to mitigate the effects of COVID-19 is the stimulation of the vitamin D endocrine system. It has been demonstrated that has pleiotropic effects on multiple organs, such as modulation of the immune system, prevention of viral infections and improvement of lung function.

Immune modulating actions include inhibition of the maturation of dendritic cells to antigen-presenting cells, inhibition of the major histocompatibility complex and, consequently, inhibition of cytokines IL-12 and IL-23. In addition, the vitamin D metabolic system is able to modulate innate immune signalling, regulating the production of antimicrobial peptides and the expression of genes involved in the intracellular destruction of pathogens. They are fundamental mechanisms for airway defence.

Dr López Miranda also showed some evidence that vitamin D levels may determine the probability of being infected by Sars-CoV-2, as well as the severity of COVID-19.

Therefore, Vitamin D supplementation could be an adjuvant and/or preventive therapy in the current COVID-19 pandemic. This is possible due to the infection[1]fighting actions of vitamin D and the interference of the immune response mechanisms of vitamin D with those used by SARS-CoV-2 for viral replication4-6 .

These data suggest that vitamin D supplementation could reduce the risk of infection and the severity of COVID-19, resulting in fewer admissions to intensive care units, reduced mechanical ventilation requirements and lower mortality. Vitamin D supplementation could mitigate the impact of the Sars-CoV-2 pandemic in a cost[1]effective, accessible and safe manner.


  1. Bischoff-Ferrari HA, Dawson-Hughes B, Staehelin HB, Orav JE, Stuck AE, Theiler R, et al. Fall prevention with supplemental and active forms of vitamin D: a meta-analysis of randomised controlled trials. Br Med J. 2009; 339.
  2. Bischoff-Ferrari HA, Willett WC, Endel J. Orav EJ, Lips P, Meunier PJ, Lyons RA, et al. A Pooled Analysis of Vitamin D Dose Requirements for Fracture Prevention. N Engl J Med 2012; 367:40-49.
  3. Choi SW, Kweon SS, Choi JS, Rhee JA, Lee YH, Nam HS, et al. The association between vitamin d and parathyroid hormone and bone mineral density: the dong-gu study. J Bone Miner Metab. 2016;34(5):555–63.
  4. Meltzer DO, Best TJ, Zhang H, Vokes T, Arora V, Solway J. Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results. JAMA Netw Open. 2020; 3(9):e2019722.
  5. Hernández JL, Nan D, Fernandez-Ayala M, García-Unzueta M, Hernández-Hernández MA, López-Hoyos M, Muñoz-Cacho P, Olmos JM, Gutiérrez-Cuadra M, Ruiz-Cubillán JJ, Crespo J, Martínez-Taboada VM. Vitamin D Status in Hospitalized Patients with SARS-CoV-2 Infection. J Clin Endocrinol Metab. 2020: dgaa733. doi: 10.1210/clinem/dgaa733.
  6. Entrenas Castilillo M, Entrenas Costa LM, Vaquero Barrios JM, Alcalá Díaz F, López Miranda J, Bouillon R, et al. Effect of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study. J Steroid Biochem Mol Biol. 2020; 203: 105751.