To the editor,
We read with interest recent “Dietary supplements and herbal medicine for COVID-19: A systematic review of randomized control trials” Feng Z et al. [1]. They have highlighted the importance of micronutrients in maintaining good immune function and protecting against COVID-19 infection.
Recent reports have brought to light 2 adverse effects after COVID vaccinations, namely thrombosis mainly cerebral vein thrombosis and exacerbation of autoimmune conditions [2,3]. We wish to bring to attention that micronutrient supplementation and maintenance will also help to protect against the adverse effects of the vaccination. This is especially important as booster doses are now being recommended in the elderly and immunosuppressed individuals. Micronutrient deficiency is a major global public health problem, the prevalence being higher in elderly individuals and middle and low-income countries.
All the class 2 micronutrients: vitamin D, selenium and zinc have the potential to boost humoral immunity and may help to boost the immune response to the vaccination [4].
Moreover, besides boosting humoral immunity these micronutrients have the potential to protect against thrombosis. Vitamin D and its metabolites through activation of VDR play an important role in thrombosis-related pathways and vitamin D deficiency has been seen in pregnant women with cerebral vein thrombosis [5]. Selenium supplementation is also associated with activation of anti-thrombotic pathways and downregulation of thrombosis, such as increased levels of prostacyclin I2 and decreased TxA2 [6]. Zinc, is also known to be an important regulator of haemostasis and thrombosis and deficiency has been implicated in haemorrhagic strokes [7].
Finally, all these micronutrients have the potential to protect against activation or relapse of autoimmune conditions. Vitamin D supplementation protects against aberrant autoimmune response through modulation of the dendritic cells and other antigen presenting cells, to keep them tolerogenic, and inhibition of Th1-type immune activity and suppression of B cells (key players in autoimmune conditions) [8]. Selenium supplementation has been shown to protect against autoimmune responses through a decrease in B cell activating factor (BAFF), increase in expression of IL-10 in end-organ tissues and upregulation of B cell regulation and upsurges of T cell regulation. Supplementation of both vitamin D and selenium is known to reduce and modulate disease activity in autoimmune thyroid diseases [8,9]. Zinc is known to play an important role in protection against autoimmunity and low concentrations have been seen in autoimmune conditions [10].
Micronutrients exert an important role in the immune system and consequently could have a positive impact on SARS-CoV-2 infection. We present an argument for addition of vitamin D, zinc and selenium, relatively cheap and non-invasive supplements to prevent aberrant autoimmune reactions and to prevent thrombosis. The target population will include individuals with nutritional deficiencies, individuals with autoimmune conditions or individuals with a higher propensity towards developing thrombosis.
Declaration of competing interest
The author declares no potential conflict of interest.
Acknowledgement
RD is supported in part by the Ministry of Health, Clinician Scientist Award [MOH -000014]; and National Medical Research Council Centre Grant [NMRC /CG/017/2013]. All authors attest they meet the ICMJE criteria for authorship.
References
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