High skin melanin content, vitamin D deficiency and immunity: Potential interference for severity of COVID-19

Due to the strong immunomodulatory effects, vitamin D (Vit-D) may be an option in COVID-19 disease. The skin pigment melanin has the photoprotective capacity, by inhibiting the synthesis of Vit-D in human. Dark skin contains a high level of melanin, which inhibits vit-D synthesis, leading to deficiency of this vitamin in certain people worldwide. It has been reported that the angiotensin II stimulates melanogenesis process. The SARS-CoV-2 uses the ACE2 receptor for the entrance into the human lung epithelial cells. Therefore, there is an interconnection between the ACE2, angiotensin II, melanogenesis and Vit-D levels in our body. An upregulation of angiotensin II is inversely co-related to the Vit-D synthesis in human. Taken together, SARS-CoV-2 may rule over the peoples having high skin melanin contents and its consequence of Vit-D deficiency. This review aims to highlight a correlation between skin melanin content, Vit-D status, immunity and the potential effects on SARS-CoV-2 prevalence in COVID-19 patients. As a novelty of this review, clinical trials on Vit-D aiming to fight against SARS-CoV-2 related pathological conditions or comorbidities in COVID-19 were included. The results of the analysed data showed that there is scientific evidence that a potential synergistic treatment with Vit-D could reduce the risk of SARS-CoV-2 infection and COVID-19 deaths.