Approximately 80% of people in the world are pigmented. Melanin, one of the major skin colour contributors which protect our skin from the harmful effects of ultraviolet (UV) radiation is evident to absorb the UVB photons, thereby, competes with the vitamin D precursor 7-dehydrocholesterol in our epidermis. Therefore, the dark-skinned people require 2-10 fold more time to synthesise adequate amount of vitamin D than the white-skinned people. Infants and people in high latitude and those who spend more time indoors are the deficient groups for vitamin D.
The facultative skin colour also depends on the complex interplay of UV radiation and hormones upon the genetic interference on the melanogenesis process of the individual. The necessity of repeated UV radiation exposure to ensure sufficient biologically active vitamin D in our body has been demonstrated.
It should be noted that vitamin D deficiency is globally prevalent, particularly in elders. The flu or flu-like transmissions are often coming out in cold and/or dry air when a low UV index has been recorded. Studies suggest that vitamin D levels increase in summer and decrease in winter. This high prevalence probably contributes to the first outbreak of COVID-19 during winter and the high mortality rate in older adults. Thus, the people having dark or pigmented skins should take an adequate exposure of sunlight along with vitamin D enriched food and supplements to fight against the COVID-19 pandemic.
The writer is an Assistant Professor of Pharmacy at the Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh.