to the editor: We read with great interest a recent article titled “COVID-19 and vitamin D—Is there a link and an opportunity for intervention?” published by Jakovac et al. (6). The article highlighted the use of vitamin D as a possible prophylactic or adjuvant measure in combination with existing antiviral treatment. We agree that vitamin D is a very important factor in overcoming coronavirus disease (COVID-19), as suggested by several researchers (2, 7).
The impact of COVID-19 on daily life and the resulting limited exposure to sunlight has made natural vitamin D synthesis increasingly difficult. In Korea (9), many people refrained from going out and stayed at home in accordance with disease prevention guidelines, while students attended online classes. In addition, quarantine for 14 days was mandatory for people returning from abroad or having contact with a person confirmed to have COVID-19. This reduction in outdoors activity would further exacerbate vitamin D deficiency (1), considering that vitamin D synthesis is dependent on exposure to sunlight. COVID-19 is known to increase mortality in patients with underlying chronic diseases (10). Therefore, management of conditions such as diabetes, hypertension, and cardiovascular disease is vital. Vitamin D is a key factor in the prevention of various chronic diseases (5). Moreover, according to a recent review study, vitamin D has been reported to minimize the risk of infection by reducing pro-inflammatory cytokines and increasing anti-inflammatory cytokines (4).
Based on these prior studies, the connection between vitamin D and COVID-19 has been highlighted. However, not only the vitamin D receptor gene, but also differences in culture, race, and dietary habits among countries could affect the association between vitamin D and COVID-19. Also, we thought that the focus is not only on increasing the concentration of vitamin D, but also on evaluating factors that may increase vitamin D bioavailability in an intervention study. For example, it is recommended that magnesium be used in conjunction with vitamin D, as it is as a necessary nutrient for vitamin D metabolism and activity (8). Moreover, vitamin A, along with vitamin D, has been reported to maintain intestinal homeostasis by regulating barrier function and mucosal immune responses (3). Thus, investigation and stratification of vitamin D-related factors and careful review will be needed for future intervention studies.
DISCLOSURES
No conflicts of interest, financial or otherwise, are declared by the authors.
AUTHOR CONTRIBUTIONS
J.H.K. and J.K.P. drafted manuscript; J.H.K. and J.K.P. approved final version of manuscript; J.K.P. edited and revised manuscript.
REFERENCES
- 1.Brouwer-Brolsma EM, Vaes AMM, van der Zwaluw NL, van Wijngaarden JP, Swart KMA, Ham AC, van Dijk SC, Enneman AW, Sohl E, van Schoor NM, van der Velde N, Uitterlinden AG, Lips P, Feskens EJM, Dhonukshe-Rutten RAM, de Groot LCPGM. Relative importance of summer sun exposure, vitamin D intake, and genes to vitamin D status in Dutch older adults: The B-PROOF study. J Steroid Biochem Mol Biol 164: 168–176, 2016. doi: 10.1016/j.jsbmb.2015.08.008. [DOI] [PubMed] [Google Scholar]
- 2.Carter SJ, Baranauskas MN, Fly AD. Considerations for obesity, vitamin D, and physical activity amidst the COVID-19 pandemic. Obesity (Silver Spring). In press. doi: 10.1002/oby.22838. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Cantorna MT, Snyder L, Arora J. Vitamin A and vitamin D regulate the microbial complexity, barrier function, and the mucosal immune responses to ensure intestinal homeostasis. Crit Rev Biochem Mol Biol 54: 184–192, 2019. doi: 10.1080/10409238.2019.1611734. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Grant WB, Lahore H, McDonnell SL, Baggerly CA, French CB, Aliano JL, Bhattoa HP. Evidence that Vitamin D supplementation could reduce risk of influenza and COVID-19 infections and deaths. Nutrients 12: E988, 2020. doi: 10.3390/nu12040988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Holick MF. The vitamin D deficiency pandemic: Approaches for diagnosis, treatment and prevention. Rev Endocr Metab Disord 18: 153–165, 2017. doi: 10.1007/s11154-017-9424-1. [DOI] [PubMed] [Google Scholar]
- 6.Jakovac H. COVID-19 and vitamin D—Is there a link and an opportunity for intervention? Am J Physiol Endocrinol Metab 318: E589, 2020. doi: 10.1152/ajpendo.00138.2020. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Panarese A, Shahini E. Letter: Covid-19, and vitamin D. Aliment Pharmacol Ther 51: 993–995, 2020. doi: 10.1111/apt.15752. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Uwitonze AM, Razzaque MS. Role of magnesium in Vitamin D activation and function. J Am Osteopath Assoc 118: 181–189, 2018. doi: 10.7556/jaoa.2018.037. [DOI] [PubMed] [Google Scholar]
- 9.MOWH Basic rules for keeping distance in life for personal prevention. http://ncov.mohw.go.kr/guidelineList.do?brdId=6&brdGubun=61&dataGubun=611. Accessed 04–28 2020.
- 10.Zhang G, Hu C, Luo L, Fang F, Chen Y, Li J, Peng Z, Pan H. Clinical features and short-term outcomes of 221 patients with COVID-19 in Wuhan, China. J Clin Virol 127: 104364, 2020. doi: 10.1016/j.jcv.2020.104364. [DOI] [PMC free article] [PubMed] [Google Scholar]
