COVID-19 and vitamin D
A study published online in Aging Clinical and Experimental Research on 6 May 2020 analysed the relation between COVID-19 mortality rates in 20 European countries and their average population vitamin D concentrations. The study was undertaken because of a known association of low vitamin D with susceptibility to respiratory tract infections. The countries with the highest CÓVID-19 mortality rates were found to have the lowest vitamin D concentrations.
Italy and Spain, with high COVID-19 mortality rates, had lower average vitamin D concentrations than most northern European countries. The authors suggested this was partly because people in southern Europe, particularly the elderly, avoid strong sun, while it is known that skin pigmentation reduces natural vitamin D synthesis.
The decrease in vitamin D synthesis caused by skin pigmentation could be relevant to the high proportion of black, Asian and minority ethnic (BAME) people dying from COVID-19. On 7 May 2020 the UK Office of National Statistics (ONS) released an analysis of the ratios of BAME to white deaths registered between 2 March and 10 April. The hazard ratios after accounting for age alone were halved when adjustment for self-reported health and socio-demographic factors were included. The ONS said the BAME/white difference “is partly the result of socio-economic disadvantage and other circumstances, but a remaining part of the difference has not been explained.”
The correlation between these adjusted hazard ratios and the degree of skin pigmentation of the ethnic groups suggests that decreased vitamin D synthesis due to greater pigmentation may be a factor.
The joint lead author of the 20 European countries study, Dr Lee Smith, Reader in Physical Activity and Public Health in Anglia Ruskin University, Cambridge, said: “Vitamin D has been shown to protect against acute respiratory infections, and older adults, the group most deficient in vitamin D, are also the ones most seriously affected by COVID-19. A previous study found that 75% of people in institutions, such as hospitals and care homes, were severely deficient in vitamin D. We suggest it would be advisable to perform dedicated studies looking at vitamin D levels in COVID-19 patients with different degrees of disease severity.”
A pre-print version of such a study that was last revised on 7 May 2020 has been published online in Social Services Research Network by Dr Mark Alipio of Davao Doctors College, University of Southeastern Philippines. He studied 212 patients with laboratory-confirmed COVID-19 who had vitamin D concentrations measured on admission, with more than one third classified as deficient. Vitamin D values were highest in the 49 patients who had mild symptoms without pneumonia and lowest in the 48 who developed respiratory failure and required intensive care monitoring.